Light and the Humble Tomato Plant

[Scoop1]

Hi all.
Reading a lot of members post's on the light requirements of the Tomato plant, there seems to be many differing views on what is best, some say shade in the hottest part of the day, some say full sun, some say use shade cloth, it certainly seems that many growers don't quite understand the difference between light and heat and how the plant interprets and responds to the two , so I thought I would try and explain a little about the light requirements of the plant, because the plant sees it different than we do. OK, the light that the plant uses for Photosynthesis for those who are not aware is called "Photosynthetically Active Radiation" this light in the 400 to 700 Nanometre Colour Spectrum only, and can only be measured accurately with a PAR meter, or which is sometimes called a Quantum meter, these meters Read in " Micromoles per square meter per one second" { the light falling on one square meter every second }.
All plants have a certain light requirement to maximise Photosynthesis and it can be very helpful for growers to understand a little about how these light energy levels affect the rate of Photosynthesis in the plant, in order to do this you should be aware of both the Light Compensation Point and also the Light Saturation Point for the plant, the Light Compensation Point is the light level at which Photosynthesis just balances respiration, put simply, the net CO2 exchange is zero , at this compensation point there is no real plant growth, but respiratory losses of CO2 are not depleting reserves in the plant either. The next important factor of light and plant growth is the Light Saturation Point, which is the light level at which any further increase in light will give no further increase in Photosynthesis, put simply the Photosynthetic system is totally saturated with light, an important factor for growers to realise that the amount of time the plant spends at or below the Light Compensation Point is not viable so knowing what this point is becomes very helpful to get much better results and much better produce, and to maximise Photosynthesis, and the perfect scenario is to have the plant sitting just above that Light Saturation Point so Photosynthesis is at its peak but the plant is not suffering from to high a light intensity. Tomatoes are C3 plants and become light saturated depending on the latitude where the plant is growing, roughly at around one half of full sunlight, but in certain areas the light intensity is much higher, for an example where i am at a 32 degree latitude here in Australia on a clear blue sky summers day the light intensity reaches a very damaging 2400 Micromoles per square metre per one second. These light levels are important not only from a photosynthetic standpoint, but also the problems associated with low light intensities and also high light intensities, low light intensity can cause high rates of misshapen fruit, poor fruit set, flower and fruitlet drop, small fruit size , slower growth, much larger leaf area and the plant becomes spindly and weak. On the other side coin, too high a light intensity causes the development of thick leathery leaves, and the leaves will also curl up or point upwards as starches build up in the leaf cells and it tries to limit the intense light falling on the leaf area, at this stage the plant is under a great deal of stress, if this continues those leaves will eventually dry out and die off. This knowledge is also very useful for the grower who maybe considering a permanent structure such as a greenhouse or just to simply employ some shade cloth, and you will have to consider what the day is going to be like, and as you are aware the sun does not shine every day, so to put your plant in the shade on a sunny day you could be well below the Light Compensation Point.
Ok, now all that said, the Optimal Light Range for a mature Tomato plant is in the range of 550 - 750 micromoles per square metre per one second, while seedlings have an Optimal Light Range of 300 -450 Micromoles per square metre per second.
The PAR meter operates by taking an instantaneous measurement every 30 seconds and then averages those readings and records a 30 minute average through a 24 hour period, the reason it records the average is because it is more of a true reading of the Light Intensity that falls on the plant because there could be a some cloud passing over the sensor within that 30 minutes as you can see by the metering's below.

The PAR Meter with the sensor and levelling plate

Colum A = averaged 30 minute meter readings from a partly cloudy day at 32 degrees latitude { 13/1/2014 } Temperature 31 degrees, Time AEDT

Colum B = averaged 30 minute meter readings from a perfectly clear blue sky day ------------- { 14/1/2014 } Temperature 28 degrees, Time AEST

Colum A Micromoles per square metre one second Colum B

5am - 5.30am = 0 5am - 5.30am = 0

6.00am = 4 6.00am = 6

6.30am = 21 6.30am = 54

7.00am = 65 7.00am = 230

7.30am = 224 7.30am = 458

8.00am = 660 8.00am = 667

8.30am = 439 8.30am = 891

9.00am = 411 9.00am = 1123

9.30am = 827 9.30am = 1339

10.00am = 612 10.00am = 1556

10.30am = 724 10.30am = 1739

11.00am = 675 11.00am = 1887

11.30am = 1040 11.30am = 2014

12.00pm = 1333 12.00pm = 2116

12.30pm = 1264 12.30pm = 2179

1.00pm = 671 1.00pm = 2209

1.30pm = 1211 1.30pm = 2203

2.00pm = 2350 2.00pm = 2159

2.30pm = 2019 2.30pm = 2079

3.00pm = 1226 3.00pm = 1967

3.30pm = 1835 3.30pm = 1826

4.00pm = 1660 4.00pm = 1658

4.30pm = 1533 4.30pm = 1496

5.00pm = 890 5.00pm = 1267

5.30pm = 488 5.30pm = 1085

6.00pm = 382 6.00pm = 810

6.30pm = 251 6.30pm = 526

7.00pm = 153 7.00pm = 225

7.30pm = 62 7.30pm = 92

8.00pm = 12 8.00pm = 26

8.30pm = 1 8.30pm = 1

9.00pm = 0 9.00pm = 0

Note # At 1.20pm on 15/1/2014 on a perfectly clear blue sky day, I took an instantaneous reading in full sun and then in dappled shade . Full Sun 1.20pm = 2201 - Dappled shade 1.20pm = 129 micromoles per metre square per one second, way below the Light Saturation Point!!.

The early signs of leaf curl from the High Light Intensity, from there it just continues to worse

I hope this helps a few growers to understand what is going on with your plants, also remember it can be very hot on cloudy, hazy, overcast days and think about the above meter readings before you shade your plants.

Cheers

Scoop

[namdocmai]

Okay so the ideal light is at dawn and at dusk, all the light inbetween those times is to strong for a tomatoplant?

I will grow them at the side of the house, not in direct sun. I have another one growing in the pond in half sun so i can test which one does grow the best.

What is the ideal lightstrength for hydroponic lettuces?

[loong]

Interesting stuff scoop, thanks for posting

[Scoop1]

Hi Namdocmai, you must have misunderstood my post a little, considering that the optimal light intensity for your plant is 550 - 750 micromoles per square metre per second, and the meter reading that I took in the Highest Light intensity time of the day, which measured 2201 micromoles, and then metered the dappled shade under a tree at the same time, which measured 129 micromoles, you can quite easily see that if the plant is in the shade, it is a fair way under the compensation point, so it is not advisable to grow your plant in the shade, its more about understanding the light intensity that you have and how to deal with it , so you can get your plants growing as close to peak level as you can, I have read many post's about what growers do when they themselves feel extremely hot , the plant ends up in the shade, and the light intensity in the shade which I have explained is way too low even on extremely clear blue sky day. I spent three months in Thailand in 2011 from April until June at several different locations and not once did I see a clear day or a bright ball of fire in the sky, it was very hazy, but extremely hot, so because I feel hot does not mean I should shade the plant because maybe the light intensity, because of the haze, is not at a level that you can use the shade to cool your plant, as I suggested in the initial post, light and heat to a plant is a little different to what you and I see and feel. Now to your question about Hydroponic Lettuce, Light intensity levels for Lettuce depends on the type being grown, I grow Icebergs and believe it or not there Optimal Light Range is, 600 - 800 Micromoles per square metre per second similar to the Tomato, and my lettuce grow perfect at that level, but you have to be a little careful at this light level with the Hydroponic Nutrient formula and its make up, there are few issues that have to be managed, if you formulate your own , its not a problem because you change things to suit the growing conditions.

Hope this has been helpful

Scoop

PS - Don't hide from what God gives you for free, control it, to so suit your growing needs!!!

[Scoop1]

Interesting stuff scoop, thanks for posting

Hi Loong, no problem, thank you, hope it helps

Cheers

Scoop

[kikoman]

I solved my light problem in a different way placing some of my 30 tomato plants in different parts of the yard, some in full sun ,some in between, some in shaded areas. The ones in full sun did not do well the one in a partially shaded area did the best, so I move all my plants out of the area of full sun.And they seem to be doing well!

What information I could use now is how, often to water, how many deep watering per week. in Thailand.

Cheers

[Scoop1]

Hi, kikoman, I grow everything in Hydroponics, so its very much different, but I can tell you that don't ever let them dry out, or the next time you water or get rain the fruit could possibly split depending on what variety they are, in Hydroponics

consistency is everything.

Cheers

Scoop

[kikoman]

Hi, kikoman, I grow everything in Hydroponics, so its very much different, but I can tell you that don't ever let them dry out, or the next time you water or get rain the fruit could possibly split depending on what variety they are, in Hydroponics

consistency is everything.

Cheers

Scoop

Thanks, 27 0f my tomato's are in containers and 3 planted in to the ground. I think I over water, but my plants show no signs of distress, Except for Two, one planted into the ground has the leaves starting to curl up like in your picture, I will shade it during the hot afternoon hours (starting with 3 shaded hours) to see if the plant improves and I have one potted plant that leaves have a fern look about it, I separated it from the others, no signs of pest.

As I am a newbie in tomato growing, I am trying to learn all I can!

Cheers

[namdocmai]

Okay thanks for the info.

Maybe you were here in the wet season but lately we don't have any clouds and full sun all day, no blue clear sky though.

I just made my first hydroponic box with the deepwater culture. The fertilizer is premixed since i don't have any metres and like to keep it simple. Just a deep box full of water with plants in nets and poppers-clay stones. Also i use a bubbler pump with a stone but all the cheapest ones. If this works well i will buy more boxes and maybe a bigger bubblerpump and stones.

I just need to figure out where to grow it, the box is 56 litre so pretty heavy to move around. I guess the side of the house is perfect, no direct sun (maybe 1 hour a day) and not superhot like in the frontgarden.

I will be happy if i can grow lettuce, tomato, cucumber, amaranth and maybe some more vegy. Good tomato's are hard to find in the supermarkets and fresh lettuce that is not bitter as well. It took a while but now even my wife eats salad and likes it. She loves sweet tomato's and i tried to grow them many times with expensive seeds that i brought from Europe but it failed every time.

What is a good calculation-rule for airbubblers? I was just searching for that on the web but can't find a good website about it. Now i have a pump for 80 baht and got the airstone for free, it works but i wonder if it can be improved by higher quality gear.

[Scoop1]

Hi, kikoman, I grow everything in Hydroponics, so its very much different, but I can tell you that don't ever let them dry out, or the next time you water or get rain the fruit could possibly split depending on what variety they are, in Hydroponics

consistency is everything.

Cheers

Scoop

Thanks, 27 0f my tomato's are in containers and 3 planted in to the ground. I think I over water, but my plants show no signs of distress, Except for Two, one planted into the ground has the leaves starting to curl up like in your picture, I will shade it during the hot afternoon hours (starting with 3 shaded hours) to see if the plant improves and I have one potted plant that leaves have a fern look about it, I separated it from the others, no signs of pest.

As I am a newbie in tomato growing, I am trying to learn all I can!

Cheers

Hi Kikoman,, great to see you are understanding a little about what is going on with your plants, you say 27 are in containers, if you have good pliable potting mix , and good drainage, you wont over water them, hopefully the potting mix will have all the nutrients required for healthy plant growth, but I doubt it , there is no such thing as a potting mix that can supply a hungry tomato plant with the required amount of nutrient for the life of a plant, as I said its all about consistency and even the best potting mix available cant sustain nutrient consistency ,now the two that are in the ground , leave them there !!! or just shade one and collect data and learn, let them curl up and watch it happen, its only two plants and its worth it, for the knowledge you will gain.

Cheers

Scoop

[soidog2]

Scoop, amazingly detailed explanation; thank you!

Bellow; two days pickings from garden, about three days apart.

Hope I got some of your info right, I prefer soil grown taste. (Buriram, mostly hot & sunny)

Best regards.

[WitawatWatawit]

Thanks scoop. Gained some valuable knowledge there. Like kikoman, I'm a newby, growing my toms in a pot inland from Jomtien, where I get a lot of sun. Before seeding, I prepare my soil well for a month with fertiliser (homemade liquid compost, usually) and nitrogen. My toms get the morning sun until about 10am when they are shaded by my large red palms, and they seem to be coming along fine. But early days. Any more advice is greatly appreciated.

Wit

[Scoop1]

Scoop, amazingly detailed explanation; thank you!

Bellow; two days pickings from garden, about three days apart.

Hope I got some of your info right, I prefer soil grown taste. (Buriram, mostly hot & sunny)

Best regards.

Good morning all, hey soidog, your look like your going alright , that's a nice bunch of M&Ms there

Cheers

Scoop

[Scoop1]

Thanks scoop. Gained some valuable knowledge there. Like kikoman, I'm a newby, growing my toms in a pot inland from Jomtien, where I get a lot of sun. Before seeding, I prepare my soil well for a month with fertiliser (homemade liquid compost, usually) and nitrogen. My toms get the morning sun until about 10am when they are shaded by my large red palms, and they seem to be coming along fine. But early days. Any more advice is greatly appreciated.

Wit

Hi WitawatWatawit, { It would be great if you could shorten your name a bit, I hate typing } just a little bit of advice, its important to realise that a tomato plant has a very high potassium requirement and with a heavy fruit load it will strip enormous amounts of Potassium from your soil { as with all flower and fruiting plants }, so if you don't mind using fertiliser salts in your soil, a 1kg bag of totally soluble Potassium Sulphate { Potash } will help enormously when the plant has a heavy crop load, and it depends on the percentage of Potassium in the Potassium Sulphate as to what will be the dilution rate you use, if for example the percentage is 41.9% Potassium { K } using a dilution rate of 1-200 , 238.7 grams of Potassium Sulphate dissolved in 10 litres of water { that is the concentrate } and then you would use 50 ml of the concentrate in 10 litres of water and that will give you 50ppm of Potassium, 100ml will give you 100ppm of Potassium and so on.

Cheers

Scoop.

[Scoop1]

Okay thanks for the info.

Maybe you were here in the wet season but lately we don't have any clouds and full sun all day, no blue clear sky though.

I just made my first hydroponic box with the deepwater culture. The fertilizer is premixed since i don't have any metres and like to keep it simple. Just a deep box full of water with plants in nets and poppers-clay stones. Also i use a bubbler pump with a stone but all the cheapest ones. If this works well i will buy more boxes and maybe a bigger bubblerpump and stones.

I just need to figure out where to grow it, the box is 56 litre so pretty heavy to move around. I guess the side of the house is perfect, no direct sun (maybe 1 hour a day) and not superhot like in the frontgarden.

I will be happy if i can grow lettuce, tomato, cucumber, amaranth and maybe some more vegy. Good tomato's are hard to find in the supermarkets and fresh lettuce that is not bitter as well. It took a while but now even my wife eats salad and likes it. She loves sweet tomato's and i tried to grow them many times with expensive seeds that i brought from Europe but it failed every time.

What is a good calculation-rule for airbubblers? I was just searching for that on the web but can't find a good website about it. Now i have a pump for 80 baht and got the airstone for free, it works but i wonder if it can be improved by higher quality gear.

Hi namdocmai, I am pretty sure that April through to June is in the hot season, if you have full sun all day, but no clear blue sky then you have some haze and that type of haze will cut down the light intensity and sometimes that can be a good thing, as to what level, it's hard to say, I will try to write another post soon on the use of shade cloth which may help sort out some of the confusion.

Deep Water Culture is very popular in Asia and a good way start, if you start small and learn a little about the pitfalls of that growing technique as with all other systems of growing in Hydroponics. Now "where to grow it", in Full Sun of course!! as said in a previous post " don't hide from what God gives you, control it, its free" ok you have a 56litre box, full of Nutrients { not water I hope } heavy yes, 56kg, but not that big, so put it in full sun and if you can afford it { I don't think it's to expensive } try and get yourself a piece of 30% shade cloth and maybe a piece of 50% shade cloth to fit and cover it , I am sure you can conjure up something and all will be good, and work from the data in the original post as to which piece of shade cloth to use on any given day, too easy!!.

Now to the air stone { bubbler } it depends on the dimensions of your container, in the ideal situation you would want an even distribution of oxygenation bubbles around the root zone without being to disruptive to the very fine roots in the Nutrient Solution maybe you can hook up another air stone to the same pump if that is possible. If you could tell me the dimensions of the box, the material that it is made from, obviously it will need to be light proof, and also do you have thermometer? as for the other vegetables , Tomato, Cucumber, Amaranth, are not really suited to your chosen growing system, but I will take some pics of some of my vegetables and the very simple and inexpensive system of how I grow them. Now the other thing is you don't have an EC meter, { checks the strength of the Hydroponic Nutrient solution } so if you could take a pic of the nutrient analysis on the bottles Part A and Part B or just type it and post it here and I will put the calculator through it and check whether it is suitable for what you are trying to achieve, also I will need the dilution rate and also how many lettuce are you growing in the box?

Cheers

Scoop

[cdmtdm]

Scoop, amazingly detailed explanation; thank you!

Bellow; two days pickings from garden, about three days apart.

Hope I got some of your info right, I prefer soil grown taste. (Buriram, mostly hot & sunny)

Best regards.

great pic soidog ... what varieties are in the photo ?

cheers

[samuijimmy]

Interesting topic.... surely day length comes up in the equation here?

Thailand runs from about 6 to 20 degrees north of the equator.... slightly longer days, as one goes north....

Map of Thailand here! http://www.mapsofworld.com/lat_long/thailand-lat-long.html

In the south one never sees tomatoes growing well, that I have ever seen at least... some where I reckon, there is a "magic line" as you guys further north than Samui (about 9.degrees north) can grow a decent tom!

I have asked Thai friends in Songkhla why they don't grow them, and get the answer, "they don't do well!" ... These are farmers, that grow a variety of other crops... if there was money to be made they would get on the band wagon!

They don't seem to do well here on the east coast islands either. (Samui & KP etc)

It would be interesting to hear from anyone say south of BKK, if they are having real success in growing them.... I had wondered if it was night temperatures that affected them, but perhaps not the case?

Comments appreciated!

[Scoop1]

Hi all, for those growers who are following the original post, I just wanted to explain a few things about those figures on the Light Intensity, all those Light Intensity figures add up to what is more important than the instantaneous or 30 minute averages and it is called a Daily Light Integral { DLI } and the DLI for Colum A is 45.1 Moles per square metre per day { 24 hour period } 1 million micromoles = 1 mole {sorry I don't have the DLI for Colum B } and a Tomato plant's optimum is around 20 - 25 Moles per square metre per day { 24 hour period } but the PAR Meter only recorded positive values over 15 hours because, obviously the other 9 hours are the dark period and obviously the longer the Photoperiod { Day Length } the higher the DLI, as it will be in summer, and the shorter the Photoperiod the lower the DLI, as it will be in winter, so we have got, lets say, 20 moles of light the plant does not need to perform at it peak { just above the Light Saturation Point that was mentioned in the original post } , its all about how you achieve the 20 - 25 Moles per day, so you could have employed 50% shade cloth over the plant no problems at all on that day and the plant would love you for it. Now if your plant was in the Colum A's Light Intensity for that 15 hour Photoperiod without shading the plant is not going to turn up its toes and die, yes it will be under stress and eventually you will see physical signs of that stress, but this is more about getting the best out of your plant in the your individual growing environment, if you take a look at both Colum A and Colum B and take 30% { 30% shade cloth } off those figures and do the same and take off 50% { 50% shade cloth } you will see where you are as regards to the instantaneous Optimal Light intensity of 550 - 750 Micromoles per square metre per one second .

In my opinion if you want permanent shading 30% is the way to go, because it will reduce some of the Intense Light in the most intense part of the day and it wont reduce it to much during a hazy or cloudy day and you will still end up with a beneficial DLI. If you are bored and have the ability to swap between the two shading levels at the appropriate times of day and weather conditions, well that's even better.

I hope I haven't confused to many growers.

Cheers

Scoop

PS - For those who want to get a little serious , you don't need an expensive meter like a PAR meter , you can get a very cheap simple light meter used in Photography that reads either in Foot-Candles or Lux and use a conversion calculation to get a reading in Micromoles Per Square Metre Per One Second and as you are probably aware Thailand is full of camera stores.

[soidog2]

Scoop, amazingly detailed explanation; thank you!

Bellow; two days pickings from garden, about three days apart.

Hope I got some of your info right, I prefer soil grown taste. (Buriram, mostly hot & sunny)

Best regards.

great pic soidog ... what varieties are in the photo ?

cheers

The big tomatoes are a mix of :

Amelia

Solar fire

Big beef hybrid

Black Russian plum

The Cheries; they sent them to me as a free no name bonus. Have no info for you.

The big beef is tastiest & most productive.

Regards

[rice555]

Hello All, nice looking toms soidog2, been a fan of Solar Fire for a few years!

A friend of mine lives by Chi Am, I've posted some of his tom pic's before, both

run to waste and a bubbler system in white buckets with a airstone in each bucket,

the pics are in one of the hydro threads.

The pic is what I use in mixing up my nutes, got in a local ag store Korat, the also

have a store in Pak Chong. About Bt.850.

rice555

[Jotham79]

Ok, so how do I apply this to farming in Thailand? I'm at 16 degrees north if that makes a difference. Tomatoes are very expensive in the heavy part of the rainy season ( August, Sept, and Oct)and I have been wanting to try them then, but haven't been home at that time. My BIL is doing ok with shade cloth which he is mainly using to deflect excess rain. I'm looking at trying a couple of rai in the soil, potting and moving that kind of volume isn't practical. The soil is fine as tomatoes love it in the dry season.

Also, do you think all of this is as applicable to the 2 types of Thai tomatoes grown commercially or should they have developed a different light sesitivity?

[kikoman]

Great Thread, great information, keep it coming!

I made some homemade fish emulsion ( will use it very diluted) and use molasses, a dab of Epsom salt and another dab of lime. I also placed a couple of hand fulls of earth worm casings on each plant I will hold off with the fish emulsion for a week or two, afraid of using to much fertilizer at a time.

Used liquid dish soap and water spray on White flies that took over one of my jalapeno plants, I destroyed the plant as it was heavily infected with white flie eggs, the spray was very effective on the adult white flies and I took off a few lower tomato leaves the white fly were on, but will keep an eye on the fly!

Scoop 1, thanks for the watering tip!

Soi Dog2, great looking tomato's.

Cheers

[Scoop1]

Good morning all, Jotham79 , as to your question, you are at 16 degrees in the Northern Hemisphere and the sun is higher and more directly above for a fair bit of the year, as compared to the 32 degrees in the Southern Hemisphere where I am, so you have that advantage and also, depending on the elevation of your location the day/night temperature differentials are not going to be as severe as in Southern Hemisphere so you also have that advantage, and the light requirements for Thai tomatoes wont be to much different than any other tomato!, your growing tomatoes in the field not in a multi million dollar computer controlled greenhouse, and at the end of the day your tomatoes are going to have some taste . I have posted this somewhere before but I will post it again here. These days, I use this growing system for 95% of all the heirloom tomatoes that I grow hydroponically, and it may interest growers who sometimes struggle to get the results they would like in Thailand. It's basically a short term crop of long term cultivars [ indeterminate }, which may help in Thailand's weather { a quickie before the rainy season so to speak } its known as "Single Truss Cropping" and for those who are not aware of this system of cultivation it has some very important benefits, as regards to fruit flavour, fruit size and composition, and is quicker than normal long term cropping because you are only waiting for one truss of fruit to grow, mature, and ripen without any competition, which helps a fair bit with fungal diseases and pests that will ultimately attack the crop , this is how it is managed, the seedling is treated as normal until the development of 3 - 4 true leaves immediately below the first flower truss and then 3-4 leaves immediately above that truss, and then the growing shoot is removed, and then all subsequent lateral shoots are also removed as they appear, and you can grow the plants at a density of about 10-12 plants per square metre as long as there is enough light intensity { and we already know what that is } to drench the plant's leaf canopy, you don't have to grow them that densely but commercially, its is done that way, which is great if you don't have a lot of room or you grow in pots, since the average "Single Truss Plant" does not grow much taller than 1 metre tall depending on which cultivar you are growing, I grow four heirlooms per 20ltr plastic bucket with a 1.5mtr 25mm PVC pipe attached to the bucket for the stake, and they can be grown in smaller areas than normal cropping methods, it has also been proven that the taste of the fruit is enhanced and the size of the fruit is also much larger than it otherwise would be, because this one "Single Fruit Truss" has no competition whatsoever for assimilates from anymore developing shoots, new leaves or new flower trusses, these 7-9 leaves that each plant has, contribute ONLY to the production of just that one Single Truss of Fruit, which results in the extremely high compositional quality of the fruit in terms of sugars, acids and dry matter content and the overall flavour is superb. Single truss crops develop very rapidly once the growing tip has been removed, and seedlings can be planted out every 3-4 weeks so there is a continued crop of tomato's being harvested when weather permits, the only disadvantage of this system of cropping is, obviously you need a lot more seedlings, but the effort is greatly worth it particularly if you grow a cultivar that that you have grown previously indeterminately, because you will be amazed at the difference, as mentioned above, in the size and compositional quality of the fruit, but it is an absolute must that you look after those very important leaves.

You mentioned that your BIL uses shade cloth, firstly the plants are still going to get wet so fungal disease is going to be an obvious problem, secondly , if it is raining he maybe cutting back the intensity level of what light there is ,to possible below the Light Compensation Point.

And why don't you try a few heirlooms in pots before the rainy season and see how you go?

Cheers

Scoop

[Scoop1]

Interesting topic.... surely day length comes up in the equation here?

Thailand runs from about 6 to 20 degrees north of the equator.... slightly longer days, as one goes north....

Map of Thailand here! http://www.mapsofworld.com/lat_long/thailand-lat-long.html

In the south one never sees tomatoes growing well, that I have ever seen at least... some where I reckon, there is a "magic line" as you guys further north than Samui (about 9.degrees north) can grow a decent tom!

I have asked Thai friends in Songkhla why they don't grow them, and get the answer, "they don't do well!" ... These are farmers, that grow a variety of other crops... if there was money to be made they would get on the band wagon!

They don't seem to do well here on the east coast islands either. (Samui & KP etc)

It would be interesting to hear from anyone say south of BKK, if they are having real success in growing them.... I had wondered if it was night temperatures that affected them, but perhaps not the case?

Comments appreciated!

Hi all samuijimmy,, I grow Hydroponic tomatoes here in Australia, all year round and in the dead of winter the day night temperature diffs can be 15-20 degrees day and 2-10 degrees night with a Light Intensity at midday about 1400 micromoles on clear sunny day, and never have a problem even with the heirlooms I grow, so there really is no excuses, when I finally arrive in Thailand there is only 2 things I will be concerned about , 1- the humidity and the fungal disease problems that it can cause and 2- the uptake of calcium also because of the high humidity, and yes you are correct the longer day length , the higher the DLI, but there is only so much the plant needs and that's why its possible to grow Tom's in winter, if you place them in the best possible position, that's why I grow in 20ltr buckets because I can change the position to suit the season and make the most of the light available.

Cheers

Scoop

[samuijimmy]

Interesting topic.... surely day length comes up in the equation here?

Thailand runs from about 6 to 20 degrees north of the equator.... slightly longer days, as one goes north....

Map of Thailand here! http://www.mapsofworld.com/lat_long/thailand-lat-long.html

In the south one never sees tomatoes growing well, that I have ever seen at least... some where I reckon, there is a "magic line" as you guys further north than Samui (about 9.degrees north) can grow a decent tom!

I have asked Thai friends in Songkhla why they don't grow them, and get the answer, "they don't do well!" ... These are farmers, that grow a variety of other crops... if there was money to be made they would get on the band wagon!

They don't seem to do well here on the east coast islands either. (Samui & KP etc)

It would be interesting to hear from anyone say south of BKK, if they are having real success in growing them.... I had wondered if it was night temperatures that affected them, but perhaps not the case?

Comments appreciated!

Hi all samuijimmy,, I grow Hydroponic tomatoes here in Australia, all year round and in the dead of winter the day night temperature diffs can be 15-20 degrees day and 2-10 degrees night with a Light Intensity at midday about 1400 micromoles on clear sunny day, and never have a problem even with the heirlooms I grow, so there really is no excuses, when I finally arrive in Thailand there is only 2 things I will be concerned about , 1- the humidity and the fungal disease problems that it can cause and 2- the uptake of calcium also because of the high humidity, and yes you are correct the longer day length , the higher the DLI, but there is only so much the plant needs and that's why its possible to grow Tom's in winter, if you place them in the best possible position, that's why I grow in 20ltr buckets because I can change the position to suit the season and make the most of the light available.

Cheers

Scoop

Hi Scoop~ ! Thanks for adding some input here,. Where I was from in Canada roughly 49 north, (British Columbia) they use lighting during the winter months... for Hydroponic toms, which the Californians love..... and it's a huge export... (amazing but true) during the summer season light is OK... for hydroponic or soil grown Toms!

I was hoping here to see how far south here in Thailand people were having success in growing decent Toms, seems the guys in the northern regions of Thailand are having success... but as I said, not so much luck in the southern areas... (down the "leg" of the country... ) .... me ...just wonders where that magic line is! ?

Many hydroponic Lettuce, farms in the southern area, (at least six on Samui...) but there are times I've seen just about the whole crop having to be thrown out, due to disease... mostly due to weather conditions.......... they don't use fungicides!

Seems most members on this Farm forum are northern farmers! There is a difference in a number things that can be grown in the north, than at our latitude here!!!..... lucky for you guys!

[Dr. Burrito]

Tomatoes. Joy, joy. My entire childhood was hoofing it down a tomato row, or so it seemed at the time.

Sun, yep, they love sun, but the heart of the summer is tough on them.

Certainly use shade clothe when you go from sowing tray to transplant tray until the root system as assimilated to the new soil, then they are relatively okay in direct sun during the heat of the day, but until you are ready to transplant to the field, you can somewhat keep them shaded. But at least 3-4 days minimum before you transplant (this all assume fields and larger volume where cover is not pratical) then you'll need to leave them out to toughen up. Watch where the base of the plant starts to turn purple.

We grow a variety called Mountain Spring, but for the hard part of the summer, they don't thrive the same and we switch over to Arkansas Traveler or Homesteads as well as the hybrids.

We generally start up tomatoes in February in the greenhouse and then sow more every 4 weeks for at least a total of 3 crops through the summer.

Dr. B

[Scoop1]

Hello All, nice looking toms soidog2, been a fan of Solar Fire for a few years!

A friend of mine lives by Chi Am, I've posted some of his tom pic's before, both

run to waste and a bubbler system in white buckets with a airstone in each bucket,

the pics are in one of the hydro threads.

The pic is what I use in mixing up my nutes, got in a local ag store Korat, the also

have a store in Pak Chong. About Bt.850.

rice555

Hi Rice, hope you are well, I noticed the analysis on the bag it is fertigation grade and from what I can see is that 50-51% can you clarify that for me please, and why do you need such a large bag, how much are you using in your nutrient, I have a 1kg bag at 41.9% and have had it for 12 months and still have 75% of it left, are you using in your soil bound plants as well? it just seems like a lot of Potash to have for hydroponics,

Cheers

Scoop

[rice555]

Hello All, Scoop1 I'm sorry I missed this thread and didn't repl.,

I use 250gms in each time I mix up a 10Lt. batch of "B" concentrate.

This is basically what I've done since I started weighing my own, this

is the basic WESCO formula.

rice555

[samuijimmy]

This is an interesting BBC program, some one posted on the Samui forum, takes about an hour, but quite interesting ... re taste....

at about 39 minutes is where the tomato is talked about in more detail....

http://www.youtube.com/watch?v=_np-f6zVb98

A couple of successfully grown tomato plants near me on Samui....

Grosse Lisse variety brought in from Oz!

The Thai lady who grow these yanked them out a couple of days after the pics were taken .... said too slow!

A local Samui hydroponic grower is experimenting with Toms and a few other things .... It's going to be interesting to see how he does!

This is his first crop....just developing.... looks like a Roma type...

[rice555]

This is an interesting BBC program, some one posted on the Samui forum, takes about an hour, but quite interesting ... re taste....

at about 39 minutes is where the tomato is talked about in more detail....

http://www.youtube.com/watch?v=_np-f6zVb98

A couple of successfully grown tomato plants near me on Samui....

Grosse Lisse variety brought in from Oz!

The Thai lady who grow these yanked them out a couple of days after the pics were taken .... said too slow!

A local Samui hydroponic grower is experimenting with Toms and a few other things .... It's going to be interesting to see how he does!

This is his first crop....just developing.... looks like a Roma type...

Hello All, samuijimmy can you ask what verity they are the next time you pass by?

The two pic's are Yaqui VFFNA Hyb., my second time growing them with good

producing plants. If you will enlarge the pics, you can see what you can grow in the

driveway.

The 3rd. pic is same, but my wife grew in the dirt in Feb. Usually only 3 per cluster

and smaller than the Dec/Jan hydro.

rice555