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Horticulture has been scientifically studied for hundreds of years. Therefore, the optimal growing of plants for health, flavor and beauty takes practice and the proper application of information. Although hydroponic growing is a small branch of knowledge compared to all gardening science, the knowledge available is still large. Because of this we can't answer all of your questions without writing several books ourselves. Therefore, we recommend the excellent book 'How to Hydroponics' depicted here for a more complete information source.
What is Hydroponics?
The modern definition is that hydroponics is the growing of plants without soil. When you grow a plant hydroponically, all the nutrients and all the water is readily available to the plant (traditional potting mixes only release about 70%). Thus in hydroponic the plant does not have to work hard to get the food and water. It can therefore spend all it's energy on growing the plant instead of growing roots. In soil the big root net is necessary for the plant to be able to find enough food and water.
If not Soil, Then What?
Typically, there are several types of growing media for hydroponic systems.� These
are all courser than soil so that there are air/water pockets between the granules that allow the plant's root system to breathe better (gives the root systems better access to oxygen, which is essential).� These growing media include,
- Coconut Coir (shredded Coconut husks, common trade names are Ultrapeat, Cocopeat, Coco-tek)
- Perlite (air puffed glass pellets)
- LECA (Lightweight Expanded Clay Aggregate)
- Perfect Starts (molded starting sponge)
- Rockwool (molten rock spun into glass-like fibers)
- Combinations of the above
All of these media are readily available on the market.� The perfect growing
medium has the following characteristics;
- Holds an even ratio of air to water
- Helps to buffer pH changes over time
- Is easily flushed and re-wets easily after storage
- Is reusable or biodegradable to insure safe disposal
- Is inexpensive and easy to obtain
- Is lightweight and easy to work with both indoors and out
What are the benefits of hydroponic growing?
Cultivating plants hydroponically is an easy and environmentally sound way to grow a wide variety of healthy plants. It offers numerous benefits over growing in soil, including:
- Plants grow up to 50% faster because they have easy access to food and water.
- Plants become "vacation-proof" and "neglect-resistant" as hydroponic growing methods conserve water so well, you only need to add water every three to six weeks!
- Plants can "tell" you when to water, because they droop before wilting and damage occurs.
- Little or no pesticides are necessary. Plants start out in a disease-free medium.
- If disease occurs, it may only affect one plant, not a whole row.
- You use smaller containers, because the roots can grow throughout the media without being rootbound
How should I maintain my Hydro System?
Keep it clean
Always cut off dead leaves and remove them from the grow room. Decaying organic matter attracts fungus gnats. You should also remove diseased plants, so the infection does not spread. Clean the plant box well with a 10% bleach solution before putting it back in the grow room. When you change water in your stock tank, wash the tank well with a 10% bleach solution. If you use big trays for your blocks and slabs consider washing these too, especially if you have had a problem in the past with root rot.
Drippers
If you use a drip system buy a few extra drippers, so you can change drippers if any are clogged up. Have a bucket with vinegar in your grow room and throw the clogged drippers in, so they will be clean and ready to use next time you need to change a dripper.
Ebb/flood systems
We recommend that you spend an extra couple of dollars and get a timer that can be set at 5 minutes intervals, so a full cycle will only soak the stonewool for 10 minutes. To avoid salt built up we suggest that you top water your plants once per week. Also be sure to have a tray with deep enough grooves that none of the stone wool cubes/slabs sit in water.
EC and PH
The EC level varies depending on which plants you are growing. The rule of thumb is EC 2.5. The pH in your tank and in the growing space will go up - it is a natural response - it means your plant is growing! 24 hours before planting, don't forget to saturate the stone wool with pH 5 water. Never go below pH 5 or the stonewool may be damaged! Below pH 5 and higher than pH 7 the plant cannot readily take up nutrients.
STOCK TANK SOLUTION
We recommend that you completely change the solution once a week. Yes, you can top up the tank and adjust EC/pH, but your solution may be out of vital micro nutrients or be infected with Phytium (root rot). If your stock tank contains ready to use (diluted) nutrient solution, please use phosphoric acid (or lemon juice) as pH down'er. If you have a fertilizer injector connected to a tank with concentrated solution, it is better to use sulphuric acid as pH down'er.
LEARN FROM YOURSELF
Consider keeping a journal that lists: the EC, pH, temperature, CO2 & light level each day. This way you can learn from your own mistakes & successes. Records like this also make it a lot easier for the shop to answer your questions when you have a problem.
CHECK THE BASICS
Before you blame your plant food for unhappy plants, check your journal. Everything must be in balance. Change one parameter at a time and look for the effect. A common problem is stock water that is too cold. Consider putting a heating element in the tank (to 70�F) or put heating mats under the system. If you have trouble getting the plant to set flowers/fruit try to make a greater difference between night and day temperature. If that is not enough, increase CO2 injection during daytime.
A COMMON PROBLEM:
Calcium deficit
If the youngest leaves are curled downward, more than likely it indicates a calcium deficiency. If old leaves are curled; something is probably wrong in the root zone (which also reduces the calcium uptake)
Calcium deficiency is the result of insufficient water movement through the plant. Remember, calcium only travels in the water stream of the plant, not in the nutrient stream. Therefore, calcium deficiency is usually (90% of the time) related to the climate in the growing area. High humidity will prevent calcium uptake even if there is sufficient Ca in the feed solution. Also, large day/night fluctuations in humidity will disrupt the Ca flow within the plant and lead to blossom-end rot (BER).
Another cause of BER or obvious Ca deficiency in the leaves is poor root development. This is a result of low substrate temperatures or the presence of a root pathogen such as Pythium or Phytophthora. Calcium is taken up by the area of the root immediately behind the root-tip. If the roots are not actively growing, new root tips will not be formed and consequently, Ca uptake will be reduced.
CHECK THE PLANT!
Make a habit of taking a close look at your plants every day. Do they look perky? Look for leaf color, leaf shape and bugs, then update your journal. If you catch a problem early it can be fixed!.
CONTROLLING YOUR HYDROPONIC PLANTS
We suggest that you first familiarize yourself with the above section on 'Maintaining your hydroponics system'. There we encourage you to, among other issues, check the appearance of your plants every day.
The following table helps you trouble shoot problems with your plant environment.
For plants, we talk about two stages:
vegetative, (leaf and stem growth)
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 photosynthates (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. When you use the following table as a tool for trouble shooting please:
Do not change all 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.
The figures in the table below should be viewed as rule of thumb only. They are based on tomato plants' responses to changes in the environment.
NOTES:
- Do not inject CO� at night.
- No light, no water !
- 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 no reason to worry about that. During the night just maintain the 70� room temperature and the slab water content.
- When you grow in a closed room, CO2 will, because of the plants, be around 300 ppm. Therefore, for vegetative growth there should be little or no CO2 injection.
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