Perhaps you’ve seen hydroponic produce at the grocery store or driven by a hydroponic greenhouse and wondered how hydroponic gardening works. You may be surprised to learn that it’s an easy way to grow all kinds of plants in your own home, and because it’s gaining popularity, hydroponic gardening supplies are easily available today. You can even create your own hydroponic systems on any scale you desire. Here’s a look at the basics of hydroponic gardening, what you need to start out and why this form of growing is so much in favor today.
Hydroponics is a system of growing plants without soil, using liquid or a non-soil growth medium and a nutrient-rich solution to feed the plants. All you need for a hydroponic garden is a structure to hold the plants, nutrients, growth medium (optional), a light source and plants. Hydroponic gardening done with just liquid nutrients is known as solution culture, while aggregate culture refers to plants grown in a medium, such as clay, sand, pellets or gravel (see below).
Hydroponic structures can be purchased as large-scale or even commercial systems or as small kits for home hydroponics novices. These come in a variety of vertical tube and horizontal tray designs. Some are modular and can be added to as need demands. You can even build your own structures (see below).
All hydroponics systems need the same basic ingredients to promote plant growth: water, nutrients and oxygen. There are many different ways to bring the nutrients to the plants, including flow, ebb, drip, aeroponics and wick systems.
Benefits of Hydroponics
Why has hydroponics become so popular lately? There are a host of reasons:
- It’s a great option when you have no yard space, low levels of sunshine or long periods of little sunshine in northern latitudes.
- There’s no dirt involved, so there’s no mess. Hydroponics lends itself well to indoor gardening.
- It’s a good option when you have poor or contaminated soil in your yard.
- You can grow vertically, which makes it ideal for small spaces.
- Hydroponics is simple, which makes it perfect for novice gardeners and kids.
- Without worrying about soil, you control every element of what you put into your plants, which is especially important if you plan to eat them.
- Hydroponics is versatile; you can fill a greenhouse or just one corner of the kitchen.
- You can garden all year round, including growing your own fresh produce.
- Gardeners can grow flowers, vegetables, herbs and fruits with hydroponic systems.
- You can have as much input into the system as you want, from building everything from scratch to purchasing a kit to hiring a consultant to custom design a system for you.
- Hydroponic harvests can exceed the yield of traditional gardening, including organic gardening. (Hydroponics can’t technically be called organic, because it doesn’t use soil.)
- You generally find faster growing cycles with hydroponics.
- Hydroponics is perfect for gardeners who find conventional garden labor prohibitive, due to a disability, for example.
- Hydroponics is economical and can be low-cost.
- Hydroponic gardening is sustainable and environmentally-friendly.
Solution Versus Aggregate Cultures
When setting up a hydroponic garden, you’ll need to decide whether you want to use only a solution culture or use some sort of aggregate as a growth medium. Your decision will be influenced in part by the size and sturdiness of the plants you grow, the structure of your system and the root development of your plants.
Plants with shallow roots, like leafy greens, do fine in solution cultures. On the other hand, plants with deep roots, such as beets, do better with aggregate systems, as do top-heavy vegetables, such as squash and cucumbers.
Aggregate cultures can use a variety of growth mediums, including:
- small clay rocks (sometimes called hydrocorn)
- peat moss
- coconut fiber or chips
- sterilized pea gravel
These are fairly inert ingredients, meaning they won’t decompose or break down quickly. Therefore, they provide a more stable environment to hold nutrients for the plant roots. Roots that are submerged in growth medium shouldn’t be allowed to get too soggy, or they will suffocate. (Solution-only systems use air pumps to generate bubbles to provide oxygen to the plant roots.)
You can use a single type of aggregate, or you can mix growth mediums. Many savvy garden centers these days offer a good selection and can help you compose the perfect material for your hydroponic garden.
Whole volumes could be written about nutrient systems for hydroponic gardens. There are hundreds of commercially available pre-made solutions today. Some store-bought solutions are ready-to-use, while others need to be mixed, combining primary, secondary and micro nutrients. You can buy special solutions for different types of crops too, based on the chemical elements those plants need most.
You can also mix your own solutions to get just the right nutrient mix. For example, to grow strawberries, it is recommended to use 50 milligrams of nitrogen and 150 milligrams of potassium per liter of solution. Cucumbers, however, to better with 200 milligrams of nitrogen and 280 of potassium.
Nitrogen is essential to create chlorophyll, as well as to build amino acids that make up proteins. Sulfur is another important amino acid element. Both potassium and magnesium help plants build starches and sugars, and calcium contributes to cell wall structure. Phosphorus is vital for photosynthesis. Micronutrients needed in trace amounts include:
Your plants will often tell you if they are receiving too few or too many nutrients. Not enough nutrition and the leaves will turn yellow; too much and they will look brown, burnt or curled.
Make Your Own Nutrient Solution
Here is a recipe for a basic nutrient solution that you can make yourself. The proportions are for mixing in quantities of five gallons (20 liters):
- 5 teaspoons (25 ml) CaNO3 (calcium nitrate)
- 1/3 teaspoon (1.7 ml) K2SO4 (potassium sulfate)
- 1-2/3 teaspoons (8.3 ml) KNO3 (potassium nitrate)
- 1-1/4 teaspoons (6.25 ml) KH2PO4 (monopotassium phosphate)
- 3-1/2 teaspoons (17.5 ml) MgSO4 (magnesium sulfate)
- 2/5 teaspoon (2 ml) trace elements
Store your solution in food-grade containers, such as old milk jugs. Make sure to shake it well before using. Keep your solution away from light at room temperature.
Water for your Solution
You need to be much pickier about the water you use with a hydroponic garden than you do with a traditional soil garden. This is because the plants are absorbing much more of whatever is in the water, and there is no soil to act as a filter for undesirable elements.
Be sure to use raw water that does not contain any sodium, chloride or fluoride. This means using water straight from the tap is out in most cases. Use a pure water supply, or treat your water with an ion-exchange system or desalinization. You cannot use softened water for hydroponic gardens, as it has far too many additives in it. If you have hard water that is free of fluoride and chloride, you can purchase nutrient solution that is designed to balance its hardness.
Solution pH Levels
Keep in mind that you should probably test periodically to make sure your nutrient solution is at the optimum pH for your plants. Most plants prefer a slightly acidic growing solution, somewhere in the range of 5.8 – 6.3 (7 being neutral). Solutions at a pH below 5.8 will cause your plants to lose calcium and magnesium.
You can easily test your solution pH with a home testing kit from your garden center or online retailer. If your solution is too alkaline, you can use dilute sulfuric, phosphoric or nitric acid to increase the acidity.
Light is an essential component of growing plants. Like with any garden, you can use natural sunlight to light your hydroponic garden. You can also use artificial lights, such as:
- high-pressure sodium bulbs
- metal halide
- high-output fluorescents
- compact fluorescents
You may want to use natural light when it’s available and artificial light at other times, so consider how portable you make your system if you intend to do this. Also, keep your light system fairly flexible, so you can adjust it as your plants grow, much like when starting seeds indoors.
Starting Out: A Few DIY Options
Plastic Storage Tubs as Your Structural Base
You can create easy DIY hydroponic systems at home using readily found items or even containers you may already have around the house. You can convert a plastic storage tub with lid into a mini hydroponic garden in an afternoon. Some people also use this method to start plants, transplanting them into a conventional garden once they’re big enough and the weather is conducive.
You can also stack multiple storage tub hydroponic units on a rack to maximize your growing space. If you put wheels on the base, it will be easy to move in and out of the house or to follow the sun on a deck or patio.
The bottom container holds a reservoir of nutrient solution that gets pumped through the entire unit, and the base is a good location for larger, heavier plants as well. Use the uppermost rack for lightweight herbs and small flowering plants (there’s no rule that says you can only grow food with your hydroponic system). This is a simple and elegant solution for apartment dwellers, seniors or even school classrooms.
Plastic Storage Tubs with Wicks
If the systems above feel too challenging to start out with, you can create an even easier home hydroponic garden with a wick system. Any two containers nested one on top of the other will work for this type of garden. Two plastic paint buckets or two plastic storage bins are ideal. In the bottom container place your reservoir of nutrient solution, and in the top container place a growth medium and your plants. Cut small holes in the bottom of the top container through which you can run wicks to transport your nutrient solution from the base to your plants.
For your wicks use braided polyurethane yarn or a fibrous rope. Stay away from cotton or nylon, as the former will rot too quickly and the latter won’t wick the liquid well enough. Run a piece of PVC pipe vertically through your system to act as a nutrient fill tube when you need to replenish your solution.
No pumps or tubing are needed for this setup, making it perfect for locations without electricity or when you don’t have access to aquarium supplies. It’s also a wonderful project to let kids manage, as once it’s established, it takes a minimum of maintenance to see results.
Aquarium Water Culture Systems
If you want a system that uses little to no growth medium and only liquid culture, an aquarium provides the perfect container. Many people have an old one sitting around the garage or basement, and this is a great way to put it to good use. Even purchasing one new is a small cash investment for the amount of produce you can grow in such a small environment. Aquarium systems are well suited to growing water-loving plants, like lettuce and other greens.
Cut a thick piece of styrofoam (one inch thick or more) to serve as a platform at the top of the unit. Make sure its dimensions are smaller than those of the aquarium, so it can float freely at the top of the garden. Set an aquarium air stone at the bottom of the unit, connected to an air line running to an air pump, just as you would for fish. This supplies oxygen to the plant roots.
Fill the aquarium about two-thirds of the way full with your nutrient solution. Next, cut holes in the styrofoam, and insert plastic cups with no bottoms to hold your plants. Gently place the styrofoam tray with your plants in the solution. The ends of the roots should dangle in the nutrient liquid. If your plants are too small or fragile, you can add a tiny amount of growth medium in each cup to hold them steady and vertical. Simply lift up the corner of the styrofoam platform whenever you want to check on your solution or add more.
The handier you are and the more time you have available, the more creative you can get with your hydroponic systems, especially once you have a little experience growing like this under your belt. You can start off small and expand your garden as you gain know-how, or if you don’t mind a bit of trial and error, take on a big system right out of the gate. You can even video or blog about your process and results to help other novice hydroponic gardeners get their gardens started. You may enjoy hydroponic gardening so much that you never go back to digging in the soil again!