Controlling your hydroponic plants

We suggest that you first familiarize yourself with our helpful tip labeled ‘Maintaining your hydroponics system’. In that publication we encourage you to check the appearance of your plants every day, among other issues. The tables below will help you to trouble shoot problems with your plant environment.

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For plants we talk about two stages: the vegetative (leaf and stem growth) and the generative (bloom and fruit growth). A plant should always have a good balance between the amount of leaves and the amount of blooms or fruit. As an example consider a tomato plant. If you have too few leaves, the plant does not make enough photosynthate (sugars). This will reduce the availability of sugars and water flow to the flowers and growing fruit. The results are smaller and possibly fewer fruits.

Controlling
Greenhouse tomato-vegetative
Controlling
Greenhouse tomato-generative

When you use the tables as a tool for trouble shooting, please do not change all the parameters at once. This will result in the plant becoming too vegetative or too generative. Choose the parameter that differs the most from the table and adjust that one. Wait a while to see if you have achieved the desired effect. If this does not perk up the plant, then find the next obvious parameter to change. It is almost like making soup. If it doesn’t taste good, you don’t mix in a number of ingredients all at the same time to make it taste better. You add a little bit of one, then taste. Then you might try another if it didn’t work. You apply the same idea when you encounter a problem with your plants.

Remember: If it is not
broke, don't fix it !!

VEGETATIVE

Parameter Humidity (Air) CO2 Root zone and reservoir Room temperature E.C. (Electric Conductivity) Water content in GRODAN slab
12 hours/day
1000 W bulb
80% 400 ppm 70-75° day & night 70° 2.5 day & night 75°
12 hours/day
400 W bulb
75% 300 ppm 70-75° day & night 70° 2.0 day & night 75°

NOTE: During the night when you do not have your grow light on, the humidity will naturally go up a bit as the air cools. There is no reason to worry about that. During the night just maintain the 70º room temperature and the slab water content.

When you grow in a closed room, CO2 will be around 300 ppm because of plant respiration. Therefore, for vegetative growth there should be little or no CO2 injection.

Pepper production with Gro-Slabs™
Pepper production with Gro-Slabs™ in greenhouse.

 

GENERATIVE

Parameter Humidity (Air) CO2 Root zone and reservoir Room temperature E.C. (Electric Conductivity) Water content in GRODAN slab
12 hours/day
1000 W bulb
75% 750-1000 ppm 70-75° Day 75°
Night 70°
2.5-3.0 Day 70°
Night 60°
12 hours/day
400 W bulb
70% 500-750 ppm 70-75° Day 75°
Night 70°
2.5 Day 60°
Night 55°

NOTE: Do not inject CO2 at night. 

The figures in the above tables should be viewed as rule of thumb only. They are based on tomato plant responses to changes in the environment inside under grow lights. Greenhouse and outdoor environments will of course have some different parameters and others that can not be managed.