Guest Contributor: Cassey Anderson, Horticulture Agent, Colorado State University Extension
Indoor hydroponic systems allow you to grow a variety of crops year-round using nutrient-rich water instead of soil, making them ideal for winter gardening in cold climates. In this article, we'll explore two primary approaches to hydroponics, and how to care for your hydroponic garden.
November sees most gardeners wrapping up in their garden and hibernating for the winter season. However, there are options if you want to keep the harvest (and donations!) going. One option is going to indoor gardening, particularly hydroponic gardening. Hydroponic gardening is a successful way to take advantage of your already heated home space. There are two primary ways that hydroponic gardening can be successfully accomplished: purchased growing systems, or DIY home-made systems. There are pros and cons to each but let’s dive into an exploration of them!
What is hydroponics?
First off, what is hydroponics? In its most basic form hydroponics uses nutrient-charged and aerated water to grow plants, largely short-to-harvest crops such as greens or smaller plants. It is important to maintain good oxygenation in the water, and to stay on top of nutrient levels, too little and the plants won’t grow, too much and they may die, so some math or calculations are involved for success.
There are many different hydroponic systems in varying levels of complexity. Some of the most common include deep water culture, ebb and flow, and NFT (Nutrient Flow Technique). Each system moves water and aerates the roots of the plants in a different manner, but the basic principles are similar. You can read more about these systems at the link below or through many other Extension websites.
Types of hydroponic gardening systems
Pre-Built Hydroponic Growing Systems:
Pre-made hydroponic growing systems are generally quite pricey unless you get a very small “countertop” setup. Systems that are large enough to supply a family of four with fresh greens can run between $600-1200. However, these systems are about as close as you can get to “plug and play” for hydroponic gardening. Many have system timers and “smart apps” that remind you when to check water levels, when to add nutrients, and when to refresh the system. Some even have monthly subscriptions that will send you new seedlings to keep the harvest going. While pricey, they certainly are a simpler way to dip your feet into the world of hydroponic growing.
DIY Hydroponic Systems
DIY systems can be much less expensive than their pre-made counterparts, but there may be some trial and error. They can be as basic as a pump in a 5 gallon bucket, or as complex as an entire side of a room with several levels and shelves. For budget options buckets and plastic bins are popular choices. Choosing effective pumps, measuring nutrient levels, and supplementing light are all considerations to make. Lighting can be simple or complicated. If you look at the pre-made systems above, they all have integrated lighting. However, you can use natural light (usually at the consequence of reduced production), you can use fluorescent lights that are somewhat effective but a little less expensive, or you can purchase plant-specific LED lighting systems. Many communities have a local hydroponic store, and you can work with them to start a build if the DIY approach appeals more. There are also plenty of online resources to support your hobby hydroponic efforts.
What can be grown indoors?
What can you plant? Lots of things! Lettuce, herbs, mustard, kale or other leafy greens can grow very well in any hydroponic system. And if the conditions are right, they can grow FAST, you may get a harvest in less than a month if you’re growing lettuce or other greens. If you have supplemental light or plan to grow outside in the summer you can go further and grow tomatoes, cucumbers, or even strawberries. Be aware that heat-loving plants such as tomato or a strawberry may struggle to grow well indoors without sufficient heat and light. Unfortunately, root crops, plants that need a lot of support or that have a very large root system may not be good candidates to grow hydroponically. That said, in science everything can be a viable experiment so if you have the time and the resources, and a desire for an uncommon crop, why not try it and see how it works!
Starting and growing plants: depending on what type of system you go with you may or may not be able to start your seedlings directly. If you have coconut coir, peat plugs, or rockwool starter cubes you may be able to put your seeds into them and then start growing directly. If you’re growing in different media such as perlite, vermiculite, or expanded clay pellets you may need to start your seedlings in one of the starter cubes, or transplant from traditional seed starting mix.
Nutrients for success: The nutrient needs of hydroponic systems can be relatively simple (purchasing ready-made nutrients) or complex (making your own mixes for varying stages of plant development). If your goal is to grow leafy greens for home use and donation it’s easy to purchase a “Nutrient A” and “Nutrient B” hydroponic mix. These can be either in solid or liquid formulations. It is important to note that you should not pre-mix the A and B solutions as they can react together and become unavailable for plant growth (this is a case of trust me as I have learned the hard way!!). Generally, these two formulations are made up of approximately 17 vital macro- and micro-nutrients for plant growth, but always include nitrogen, phosphorous, potassium, calcium, magnesium, iron, copper, sulphur, zinc, boron and other micronutrients. If you do make your own mix of nutrients, be aware that excess quantities of some nutrients will reduce efficacy of other nutrients. For example, too much nitrogen will reduce uptake of potassium.
A few final notes
A good tool to add to either a system or a DIY hydroponic setup is a pH meter, or pH testing strips. Adding nutrients to water tends to increase the pH of water. Plants like to grow in pH of around 6.5. Therefore, it may be necessary to reduce the pH of your water after adding nutrients, something you can only know by testing the water after adding nutrients.
Most hydroponic systems will need to be emptied and refreshed at least a few times a year (often when a plant cycle ends, and you start a new one). Be aware of how you dispose of your spent water. If you can send your water into a sewage treatment facility, i.e. through your household sewer line, you should be OK. The water will be high in nutrients and could be used to fertilize your garden, but could also be too high in nutrients, so be cautious if you go this approach. Avoid just dumping the water wherever as it could run off and cause nutrient issues elsewhere.
Think about how you use (or donate!) produce and grow what you know will get used! There are many more details about working with hydroponic systems, and this is just a very basic introduction but perhaps it will inspire a few of you to give it a go!
If you have additional questions reach out to your local County Extension office, or check out www.GrowAndGiveColorado.org for more information.
As always, reach out to your local Extension office with additional questions and for further resources. Happy Gardening!
Gardening in Colorado? Check out Grow & Give www.growandgivecolorado.org and in particular our Colorado Vegetable Guide https://growgive.extension.colostate.edu/colorado-vegetable-guide/ for more crop information on all of the above plants.
What if every gardener planted just one extra plant to share?
One small donation can have a tremendous impact. Just imagine, if every gardener planted one extra plant to share, collectively, we would have an abundant source of fresh, healthy produce available to be distributed to families experiencing food insecurity in our own communities! The free Fresh Food Connect mobile app connects you to a local hunger relief program, then manages and tracks your donations of homegrown produce throughout the season. Download the app today!