Tomato is a popular choice for any fertigation / hydroponic grower worldwide because of its ready market. If you ever consider to use this method to grow tomatos, this Q & A might help:
Q: How many greenhouses do I need in order to get rich?
A: Greenhouse tomato production is a highly technical horticultural business. Any new grower will make many mistakes while climbing the steep learning curve associated with starting out in the greenhouse tomato business. It advisable to start with one greenhouse, even if they intend to eventually grow an acre or more. It is much better to learn and make mistakes on one greenhouse than on 10. Starting too big is the number one reason for failure
Q: What variety of tomato should I use in the greenhouse?
A: Varieties bred for the greenhouse environment need to be used, rather than field or garden type tomatoes. All varieties are indeterminate, so that they can produce over a long harvest season. The most widely used variety in the United States is 'Trust'. Other varieties to consider are 'Match', 'Switch', and 'Blitz'. These are all Dutch hybrids.
Q: How often do I have to pollinate?
A: Pollination should be every other day, preferable between 11:00 a.m. and 2:00 p.m., when the relative humidity is lowest.
Q: How many plants can I grow?
A: Greenhouse tomatoes need between 4 and 5 square feet per plant. To determine how many plants you can grow, multiply the greenhouse width times the length and divide by either 4 or 5. Be sure to deduct any floor area used for packing, grading, sales, or equipment before dividing, since this is not usable growing space. Research at the Truck Crops Experiment Station has shown that increasing the spacing to 5 square feet per plant results in the same yield per greenhouse (i.e. higher yield per plant), even though the plant population is reduced by 20%. However, the number of physiological disorders decreases, resulting in better fruit quality.
Q: What pH should I use?
A: The nutrient solution (fertilizer dissolved in water) should be held at a pH between 5.6 and 5.8 for tomatoes grown in aggregate media (vermiculite, peat lite mixes, etc.).
Q: Some of the leaves on my plants are turning yellow. What is causing this?
A: Yellowing leaves can be caused by several situations. The following are the most common: 1) Early Blight (fungus) - If this is the cause, you should see small circular brown lesions on the leaves as well. The spots become larger. Eventually bottom leaves fall off. 2) Shading - As the plants mature, the bottom leaves get heavily shaded and naturally turn yellow as they senesce (age). This is not a problem. Any yellowing leaves are no longer productive and should be removed to improve air circulation. 3) Low nitrogen or potassium - If the nitrogen or potassium level is too low, yellowing will occur. Nitrogen deficiency shows up as a general yellowing of the entire plant. Potassium deficiency will appear as bright yellow leaf m
argins (edges) on otherwise green leaves. 4) Low Magnesium - Interveinal yellowing on older leaves is from low magnesium. It this is suspected, spray 2 TBL per gallon of magnesium sulfate (epsom salt) on the plants and see if they "green up" in a few days. For all suspected nutrient problems, a tissue analysis is recommended
Q: What is the fuzzy looking gray colored mold growing on my plants?
A: This is called gray mold (pathologists are also really good at naming diseases). The disease is also known as Botrytis, which is the causal organism. This fungus can become very serious, especially during a period of cloudy weather. It appears as a fuzzy greenish-gray mold, often growing on dead tissue. The first place to notice it is on dead flower petals, dead areas on leaves (i.e. from spray burn or mechanical damage), etc. In humid conditions, it can spread rapidly, while in dry conditions, it spreads only slowly. Improve ventilation, air movement, and apply fungicides as needed
Q: Why do the plants get flowers, but don't get fruit?
A: This can really cut into sales. There are several possibilities here. Any kind of stress on the flower can prevent fruit set. These include 1) temperature too high; getting much higher than 90ยบ F is approaching the danger zone. 2) temperature too low; 3) drought stress - i.e. if the plants are wilting; 4) using too much nitrogen - this often creates very healthy, lush, dark green plants, but few flowers or fruit; 5) salt stress - if the EC in the root zone is too high. Other than stress conditions, it is important that flowers be pollinated every other day to get good fruit set.
Q: Why do the plants produce fruit that are too small?
A: While this is not as distressing as getting no fruit set, it can still be a serious problem. Fruit should be in the 8 to 10 ounce size for standard (beefsteak) greenhouse varieties. Possible causes include 1) poor pollination - be sure you are pollinating every other day if doing it by hand (those greenhouses using bumblebees should not have this problem, unless the bees are dead). If this is the cause, the seed count will be low. You can check this yourself by cutting the fruit transversely (left to right) and seeing if the locules are full of seeds or if seeds are scarce. 2) lack of water (wilting) can cut down on fruit development. 3) high temperature stress will limit fruit size. This is very common in the hot, humid southeast, especially in May and June. 4) shading during the cloudier months prevents full development of fruit. Be sure the greenhouse does not get shaded by large trees or tall buildings.
Q: Can I grow various crops, e.g. tomatoes, peppers, cucumbers, lettuce, and strawberries, all together in the same greenhouse? Or will this create an unmanageable problem for me?
A: It is best not to grow multiple types of crops in the same greenhouse. Each has its own optimum environment (temperature, light, humidity, etc.), fertilizer, and water requirements.You could, however, grow a main crop, like tomatoes, and have a "few" of something else, just to try out. But, in that case, the system should be optimized for the main crop. If you decide to grow a larger scale of more than one kind of vegetable, it is best to grow each in a separate greenhouse which will be set up for the required conditions for that crop. But, be sure there is a market for that second or third crop. Tomatoes are the easiest to sell. Other vegetables will sell well in some areas, but not in others (for example cucumbers and lettuce).
Q: How many greenhouses do I need in order to get rich?
A: Greenhouse tomato production is a highly technical horticultural business. Any new grower will make many mistakes while climbing the steep learning curve associated with starting out in the greenhouse tomato business. It advisable to start with one greenhouse, even if they intend to eventually grow an acre or more. It is much better to learn and make mistakes on one greenhouse than on 10. Starting too big is the number one reason for failure
Q: What variety of tomato should I use in the greenhouse?
A: Varieties bred for the greenhouse environment need to be used, rather than field or garden type tomatoes. All varieties are indeterminate, so that they can produce over a long harvest season. The most widely used variety in the United States is 'Trust'. Other varieties to consider are 'Match', 'Switch', and 'Blitz'. These are all Dutch hybrids.
Q: How often do I have to pollinate?
A: Pollination should be every other day, preferable between 11:00 a.m. and 2:00 p.m., when the relative humidity is lowest.
Q: How many plants can I grow?
A: Greenhouse tomatoes need between 4 and 5 square feet per plant. To determine how many plants you can grow, multiply the greenhouse width times the length and divide by either 4 or 5. Be sure to deduct any floor area used for packing, grading, sales, or equipment before dividing, since this is not usable growing space. Research at the Truck Crops Experiment Station has shown that increasing the spacing to 5 square feet per plant results in the same yield per greenhouse (i.e. higher yield per plant), even though the plant population is reduced by 20%. However, the number of physiological disorders decreases, resulting in better fruit quality.
Q: What pH should I use?
A: The nutrient solution (fertilizer dissolved in water) should be held at a pH between 5.6 and 5.8 for tomatoes grown in aggregate media (vermiculite, peat lite mixes, etc.).
Q: Some of the leaves on my plants are turning yellow. What is causing this?
A: Yellowing leaves can be caused by several situations. The following are the most common: 1) Early Blight (fungus) - If this is the cause, you should see small circular brown lesions on the leaves as well. The spots become larger. Eventually bottom leaves fall off. 2) Shading - As the plants mature, the bottom leaves get heavily shaded and naturally turn yellow as they senesce (age). This is not a problem. Any yellowing leaves are no longer productive and should be removed to improve air circulation. 3) Low nitrogen or potassium - If the nitrogen or potassium level is too low, yellowing will occur. Nitrogen deficiency shows up as a general yellowing of the entire plant. Potassium deficiency will appear as bright yellow leaf m
argins (edges) on otherwise green leaves. 4) Low Magnesium - Interveinal yellowing on older leaves is from low magnesium. It this is suspected, spray 2 TBL per gallon of magnesium sulfate (epsom salt) on the plants and see if they "green up" in a few days. For all suspected nutrient problems, a tissue analysis is recommendedQ: What is the fuzzy looking gray colored mold growing on my plants?
A: This is called gray mold (pathologists are also really good at naming diseases). The disease is also known as Botrytis, which is the causal organism. This fungus can become very serious, especially during a period of cloudy weather. It appears as a fuzzy greenish-gray mold, often growing on dead tissue. The first place to notice it is on dead flower petals, dead areas on leaves (i.e. from spray burn or mechanical damage), etc. In humid conditions, it can spread rapidly, while in dry conditions, it spreads only slowly. Improve ventilation, air movement, and apply fungicides as needed
Q: Why do the plants get flowers, but don't get fruit?
A: This can really cut into sales. There are several possibilities here. Any kind of stress on the flower can prevent fruit set. These include 1) temperature too high; getting much higher than 90ยบ F is approaching the danger zone. 2) temperature too low; 3) drought stress - i.e. if the plants are wilting; 4) using too much nitrogen - this often creates very healthy, lush, dark green plants, but few flowers or fruit; 5) salt stress - if the EC in the root zone is too high. Other than stress conditions, it is important that flowers be pollinated every other day to get good fruit set.
Q: Why do the plants produce fruit that are too small?
A: While this is not as distressing as getting no fruit set, it can still be a serious problem. Fruit should be in the 8 to 10 ounce size for standard (beefsteak) greenhouse varieties. Possible causes include 1) poor pollination - be sure you are pollinating every other day if doing it by hand (those greenhouses using bumblebees should not have this problem, unless the bees are dead). If this is the cause, the seed count will be low. You can check this yourself by cutting the fruit transversely (left to right) and seeing if the locules are full of seeds or if seeds are scarce. 2) lack of water (wilting) can cut down on fruit development. 3) high temperature stress will limit fruit size. This is very common in the hot, humid southeast, especially in May and June. 4) shading during the cloudier months prevents full development of fruit. Be sure the greenhouse does not get shaded by large trees or tall buildings.
Q: Can I grow various crops, e.g. tomatoes, peppers, cucumbers, lettuce, and strawberries, all together in the same greenhouse? Or will this create an unmanageable problem for me?
A: It is best not to grow multiple types of crops in the same greenhouse. Each has its own optimum environment (temperature, light, humidity, etc.), fertilizer, and water requirements.You could, however, grow a main crop, like tomatoes, and have a "few" of something else, just to try out. But, in that case, the system should be optimized for the main crop. If you decide to grow a larger scale of more than one kind of vegetable, it is best to grow each in a separate greenhouse which will be set up for the required conditions for that crop. But, be sure there is a market for that second or third crop. Tomatoes are the easiest to sell. Other vegetables will sell well in some areas, but not in others (for example cucumbers and lettuce).
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