If you’re looking for a way to grow vegetables, fruits, and herbs indoors all year round, then hydroponic gardening might be the perfect solution for you! Hydroponics is a type of gardening that doesn’t use soil. Instead, plants are grown in water with added nutrients. This method has many benefits, including faster growth rates and higher yields than traditional gardening.
Deep Water Culture (DWC) is the simplest type of hydroponic system to both make and use. With this method, plants grow with their roots in water that has a lot of nutrients. For growers at home, this can be done by planting them in large storage containers or buckets that are not see-through (algae grows rapidly when exposed to light).
DWC systems don’t require many parts, which makes them cheap and easy to construct. Also, the water in a DWC system doesn’t need to recirculate the way other systems do, but you do still need to replenish the oxygen used by the roots through aeration.
In both soil and recirculating hydroponic systems, water pore spaces provide the much-needed oxygen for roots. In a DWC system, we can use an air pump with an attached air stone (typically used in fish tanks) to ensure the water remains oxygenated.
Plants that are not too top-heavy, like lettuces and light herbs, will do best in any size system, it can even be shallow with multiple holes. Since the roots are unanchored, growing taller plants like tomatoes will require a deeper single bucket (like a 5-gallon bucket), and you’ll eventually need some support for the plant.
How to Build a Deep Water Culture (DWC) System to Grow Lettuce and Herbs
1. Gather your supplies. You will need the following supplies:
- a storage container or bucket (4 to 8 gallons and preferably food grade) with a lid-not clear, must be solid colored to block out light (white is ok as long as it’s not clear)
- pH test kit or meter
- pH Down solution
- air pump (bonus: a check valve so it doesn’t suck up water into the unit if the power goes out)
- air stone
- net pots
- growing medium: clay pellets, rock wool, and coco coir all work well in DWC systems-I like rock wool
- liquid nutrients (we talk about this in the video)
- tools to cut or drill a hole depending on how thick your container is
2. Drill the holes in the lid. Net pots come in all sizes, so the most important thing you need to know about cutting or drilling the holes in the lid of your container is that they need to be smaller than the rim of the net pot. If you’re drilling more than one hole, like you would for lettuce, space them about 6 inches or more apart. Lettuce has shallow roots and can be grown in groups, but bigger plants like tomatoes and peppers will need their own individual buckets with a single hole. Also drill a small hole the same size as your air pump tubing (see video for tips on sizing).
2. Fill the container with water, test, and add nutrient solution. Place the container where you plan to keep it, and fill the container with water (use a gallon jug, so you know how much you’ve added) and leave an inch or two of space at the top. If you are using tap water, you may need to let it sit for a few days to allow chlorine levels to dissipate before adding in nutrient solution (this will depend on your brand). Once added, test the pH level and adjust with pH Down if necessary. You want the pH to ideally be 5.5 to 6.5. Add food once seeds have sprouted about an inch high or have started to show true leaves. Then add plant food according to the instructions on your nutrient bottle to determine how much to add per number of gallons you’ve filled the container with.
3. Assemble the air stone and set up the pump. Attach the air stone to the end of your aquarium-style air pump and place it in the container. Make sure that you submerge it completely, and leave enough room for any roots that may grow out of the net pots. Turn on the pump and make sure that the air stone is producing plenty of bubbles.
Tip: If you want to make several systems, you can make a cut in the tubing from the pump and add a three-way connector with additional tubing and stones to go into the other systems.
4. Place net pots in container and fill with growing medium. Place your net pots into the drilled holes, filled with your growing medium.
5. Plant your seeds or cuttings. Plant seeds, cuttings, or seedlings into the growing medium, water, then cover with plastic wrap (the rim of your container should provide a gap above the plants) and set under a grow light until the seedlings sprout to about an inch or show true leaves. Make sure they stay moist during this period (rockwood does a great job at this). Alternatively, you can place your net pots with growing medium and planted seeds in a shallow dish, covered with plastic wrap, under a light for about 10 days until they sprout, before adding them to the system.
6. Place under lights. Your garden will need 12 to 18 hours of light every day, so unless you have a sunroom or a very sunny spot in your house all year long, you may need to invest in grow lights. This varies for what you want to plant, and how big your system is, so talk to your local gardening center about which lights make the most sense for you.
7. Monitor and maintain. Monitor the pH levels of your nutrient solution regularly for optimal growth, as well as check for any blockages in the air stone that could be preventing oxygen from getting into the water. Refresh the water every two to three weeks.
You now have a simple, easy-to-use hydroponic system! If you are growing lettuces like me, it’s best to use the outer layers when you harvest; that way, the plant will continue growing, and you’ll get many salads out of each plant!
Have you used this method to grow plants before? What other tips would you add? If not, what questions do you have?