These are the very best hydroponic gardening tips that I've learned over many years of personal experience (often the hard way). I have seen many people try hydroponic gardening once or twice and fail, never to try again. The reason usually falls into one of three categories...
The hydroponic gardening tips I list/explain below will help you identify (and eliminate) problems in your garden. Even after reading advice like this myself, it took two years of making mistakes and learning things the hard way before I changed my approach and took these lessons to heart. As a result, I had the most successful garden I ever had. So, follow the tips below to shave years off of your learning curve and skip right to excellent results!
Hydroponic gardening success begins with having a solid plan. Having a plan means knowing your plants nutritional requirements and photoperiod requirements and having the supplies and equipment necessary to meet those needs. Actually having a written week by week feeding schedule, complete with nutrient strengths and nutrient changes, would also be very helpful....these feeding instructions automatically come with the nutrient starter kits from General Hydroponics and B.C. Nutrients.
Know the nutritional requirements of your plants before you start. Know how strong the nutrients should be each week of your plant's life, and know what the nutrients should consist of each week. Many plants need more Nitrogen at first, then switch to needing more Phosphorus to produce fruit or flowers. Get yourself a TDS or EC meter so you can keep track of your nutrient solution strength and adjust it as your plants grow.
Do not try to mix up your own plant food. Instead, start with a professional hydroponic nutrients product. These are usually three part systems and are complete (and easy to use). My favorite is BC Nutrients by Technaflora. Once your hydroponic gardening system is up and running and producing excellent results, then you can try mixing up your own special plant food if you like. At least then you will know exactly what the problem is if things don't work out!
The same is true for using nutrient additives. Don't try to improve your results by adding a bunch of extra things to your nutrient reservoir (at least not at first). This is one of the hydroponic gardening tips that I end up repeating to everyone that I help personally! Start by feeding just the basic three part nutrients until your hydroponic gardening system is working smoothly and producing excellent results. Then if you like you can try adding vitamin B1, liquid seaweed, or Silica (or all three).
Finally, you need to check and maintain your nutrient reservoir every day. After using the same nutrients for two weeks, you need to start over with fresh water and fresh nutrients. The most beneficial way to do this is to have two nutrient reservoirs, one with nutrient solution for your hydroponic gardening system and one with plain water for your next nutrient solution change. I can't stress how important this hydroponic gardening tip is! The second reservoir allows the water to de-Chlorinate and come to room temperature, both protecting your roots. See also my hydroponic nutrients page.
If roots become damaged, they cannot take up nutrients to feed the plants. Any damage below ground will result in damage above ground as dead leaves and sick plants. Protect your roots by maintaining your nutrient solution properly, by using two hydroponic nutrient reservoirs (one with plain water for your next nutrient change), and by minimizing the amount of light that comes in contact with your nutrient solution. This will prevent algae, which will prevent fungus gnats, which will prevent most root damage problems.
There are very few shortcuts when it comes to lighting an indoor garden. You need a minimum of 40 watts/sq.ft., but 60 watts/sq.ft. would be better. Either high pressure sodium lights or metal halide lights will do a very fine job and are the most popular choices. For various reasons I recommend either a 600 watt light or a 1000 watt light. For help choosing a light, try my light selector tool. This will be one of your largest expenses- expect to pay between $400 and $600 dollars on average for a decent system (light+reflector+ballast)(11/8/2016-not anymore, they are a lot cheaper now!).
A couple of hydroponic gardening tips on fluorescent lights: Regular fluorescent lights do not put out enough usable light for healthy growth and are only good for clones, seedlings, or very young plants in the vegetative stage (spinach, lettuce, kitchen herbs). If you decide to go with fluorescent lights in your grow room, T5 lights (aka Tek lights) are really the only way to go. While T5 lights produce less heat than HID lights, they only yield about half as much watt for watt. It is also necessary to keep the tops of your plants within a few inches of the light, which becomes a real pain in the butt sometimes.
One of the biggest hydroponic gardening tips is temperature control! Plant growth quickly STOPS when the temperature rises above 85 degrees (unless you happen to be pumping in CO2 constantly). HID grow lights put out a lot of heat, making temperature control a big issue for the indoor garden. Placing the ballast for your light outside the grow room will help (only if you have an old magnetic coil ballast, and not a nice new digital ballast lol), but even that is not nearly enough. Centrifugal fans or squirrel cage fans are an absolute must (see exhaust fan setup). In my experience, fans alone are often not enough. What is truly needed is a source of cool/cold air.
After years of organic and hydroponic gardening I have come up with only two hydroponic gardening tips for solving this problem... plan to garden indoors whenever the temperature outdoors is 55*F or less. In this way you can pull cool, dry air into your garden (from an outside source) as you exhaust the hot air. The only other option is to pump in air conditioning!
Many crops require shorter daylight periods to trigger flowering/fruiting. Two hydroponic gardening tips to success here: First, the lights need to be turned off and back on at exactly the same time each day (tip- use a digital timer!).
Second, the plants should be kept in absolute, complete, UN-interrupted darkness during the dark period. Either use a completely blacked-out room dedicated to the garden, or else use a blacked-out grow tent. Plants can be extremely sensitive to this, so don't try to skirt around this! For more info, check out my flower forcing page.
Don't start your garden unless you have all your bases covered from the beginning. You will need a completely dark area, a high powered fan, an adequate light, a hydroponic gardening system, hydroponic nutrients, an oscillating fan, a TDS meter (or EC meter), a pH test kit, and possibly an air conditioner. Minimum. A thermometer and a digital timer would really come in handy too, I promise!