What kind of nutrients to use
Plants must have certain minerals and fertilizers in order to survive. In conventional gardening, these requirements are supplied by the soil along with manufactured synthetic nutrients or organic materials. The organic nutrients may be commercially supplied or natural substances such as manure or compost.
The basic minerals needed are nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. These materials are needed in large amounts.
Other minerals needed in smaller amounts include iron, manganese, boron, zinc, copper, molybdenum and chlorine.
Obviously, it's important to provide a complete and well balanced formulation of nutrients. Pay attention to the word ‘balanced’. Many inexpensive nutrient manufacturers do not blend nutrients in a ratio that is most beneficial to plants. As a consequence, you can unknowingly create a deficiency of one or more minerals which will limit growth.
Also, be aware some manufacturers will use a cheap form of a mineral that plants cannot absorb. So become acquainted with the manufacturer of the nutrients you use and don't hesitate to buy quality. It will pay in the long run with bigger yields.
The importance of proper lighting
Artificial lighting is never superior to sunshine for plant growth. But in most grow rooms, it is the only alternative.
To provide the intensity you need for successful growing, plan on using high intensity lamps such as high-pressure sodium. These provide more than 1,000 foot-candles of light.
Also, make certain to allow adequate spacing between plants so that each receives as much light as possible. And remember that the intensity of light diminishes rapidly with distance. So you always want to adjust your lights low enough to provide optimum intensity without burning the top of the leaves.
Making certain plants have plenty of water
Normally the supply of water is not a problem in hydroponics because plants are grown in water enriched with nutrients. However, there are some systems where water can become a problem.
For example, if ebb and flow systems are not checked on a regular basis, they can run short of nutrients or become deficient in one or more minerals. And any automated system can fail because of a faulty pump, blocked pipes or other problems.
The need for oxygen
Plants need oxygen for respiration. This enables them to take up water and nutrients.
Providing root systems with the maximum amount of oxygen encourages the amount of nutrients absorbed by the plant. This results in faster growth and can greatly increase the size and quality of your yield.
If you are using a continuous flow or aeroponic system you generally don't need supplemental oxygen. Otherwise, consider aerating your nutrient by bubbling air into the reservoir.
Give your plants plenty of support
Sometimes, beginners fail to provide adequate support for their plants. This is usually done with string or stakes.
You can buy inexpensive automatic string reels to support your plants as they grow. This eliminates the task of re-adjusting the strings, particularly on fast growing plants.