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They say you can grow anything hydroponically. Now while I am not sure that’s entirely true (or perhaps I just lack the skill), hydroponics does resolve many of the limitations and difficulties that come with more traditional forms of gardening. And, if done right, certainly come with and promise of better yields. But while hydroponics may be a great alternative for growing leafy greens and herbs, I was curious as to whether the same success could be achieved for bulkier items like potatoes, onions, and turnips.
But, is it even possible to grow relatively hefty root vegetables hydroponically?
It is possible to grow root vegetables like garlic, onions, radishes, and carrots successfully within a hydroponics system. However, root vegetables grow best in hydroponics systems that can provide sufficiently supportive growth media, such as Ebb & Flow or Nutrient Film Technique (NFT).
In this article, we’ll go through the many different factors that you should consider before attempting to grow root vegetables hydroponically, from the type of system to the correct nutrients and pH levels. Let’s dive in!
Root Vegetables in Hydroponics: An Introduction
Types of hydroponic systems suitable for growing root vegetables
As you know, choosing a hydroponic system means no soil, the medium where root vegetables traditionally thrive best. It also means that your vegetables will receive water, oxygen, and nutrients from a water solution. Unfortunately, most root vegetables cannot survive when submerged in water because the tubers will rot and die.
You therefore must choose a hydroponics system where vegetables receive enough water but are still buried within the substrate. The system should also allow for a growing medium to mimic soil because root vegetables need a place to stretch their roots and develop the tubers.
I’ve written a detailed article (with diagrams) on the different types of hydroponics systems if you want to read it.
In my opinion, the best hydroponics system for growing root vegetables like radishes, carrots, and parsnips is Ebb and Flow. Let’s take a look at why.
Ebb & Flow (Flood and Drain)
Ebb and Flow hydroponics (also called Flood and Drain) is a popular form of hydroponics that is designed to regularly wash the roots of plants in a nutrient-rich solution. Within an Ebb and Flow hydroponic system, plants are positioned within large grow beds above a reservoir and supported by a loose, porous growing medium like perlite or grow stones. At regular intervals, a water pump forces the nutrient solution up into the grow bed where it then washes over the roots.
But what makes Ebb and Flow a good system for growing root vegetables hydroponically?
1. Depth
Ebb and Flow systems can be designed to have a deep grow tray. This is essential for growing root vegetables as they mostly require a lot of depth to grow effectively. The ideal substrate should be moisture retentive (but not soggy) with a decent amount of air space for the oxygenation of the roots. Clay pebbles, perlite/vermiculite, or even sand works can work quite well. But these grow mediums must be the correct depth for growing root vegetables successfully.
2. Nutrient delivery
Delivery of the nutrients can be timed (with the help of a plug timer) to match the rate of development of the plants and to avoid over-saturation of the root mass. While root vegetables usually like a lot of water and nutrients, it’s important to allow them to breathe too. Staggering the nutrient/water delivery systems helps with oxygenation and can prevent the growing medium from becoming too saturated.
3. Cost
There’s no point in trying to grow root vegetables (which are generally super cheap from the store) in a hydroponics system that costs $1000s. Fortunately, setting up an Ebb and Flow hydroponics system at home is super easy, and one of the cheapest forms of hydroponics. You should be able to create a decent system for under $200.
Best root vegetables to grow hydroponically
While there aren’t many root vegetables that you can’t grow hydroponically, some do better than others. Carrots, onions, garlic, and potatoes for example thrive hydroponically more than they do in soil. In fact, hydroponic potatoes and carrots yield up to 1500% more than their soil-grown counterparts. This is because you can better control the nutrient level, PH, and temperature in hydroponics, helping the plants thrive more.
Some of the best root vegetables to grow via hydroponics are:
- Carrots
- Onions
- Shallots
- Turnips
- Parsnips
- Beets
- Potatoes
- Sweet Potatoes
- Garlic
That said, the simplest root veggies to wet your toes with hydroponically are baby gourmet versions of turnips, radishes, carrots, and beets. You can sow them directly into the media bed, thin them lightly after germination and grow them to a succulent baby stage where they are really sweet and soft.
With potatoes and sweet potatoes, go with heirloom types even though they give lower yields than commercial varieties. They require minimal effort and you can have a constant supply of fresh potatoes all year round.
Key things to consider when growing root vegetables hydroponically
Again, growing root vegetables hydroponically requires slight changes to the soilless system. The basics remain the same because all plants need water, oxygen, nutrients, and light but the setup can be adjusted. Here are key factors to consider when growing root vegetables hydroponically.
Growing medium
As we said, root vegetables cannot be submerged in a liquid solution because the roots or tubers will rot. In the absence of soil and a water solution, you must provide a growing medium where the roots will spread and thrive.
For root vegetables, we recommend something that will allow aeration and make it easy for roots to penetrate. Clay pellets, perlite, and vermiculite are the best options in this case. You can also use peat, pebbles, or LECA depending on what vegetable you are planting.
Nutrient solution
Root vegetables are nutrient hungry but each of them requires a different nutrient blend. For example, potatoes need more phosphorus and potassium but very little nitrogen. The seedling pack should guide you on this blend and also how you will adjust the amount as the plant grows.
Light
Most root vegetables require 8-16 hours of sunlight or grow light. Find out the correct wattage required for optimum growth and figure out a way to provide enough light.
pH and temperature
The perfect PH level of a hydroponic water reservoir is 6.0 for potatoes and up to 7.5 for carrots. This will vary with each root vegetable so you have to get it right. The PH level will change if you add any nutrients or anything else to the water and you should monitor the PH and EC levels constantly. We, therefore, recommend changing the water weekly.
As for temperature, you need roughly 65-80 degrees Fahrenheit, depending on the vegetable. Again, find out the best temperature for what you plant so it can thrive.
Common problems and challenges of growing root vegetables hydroponically
Contrary to popular belief, the biggest problem with growing root vegetables hydroponically isn’t algae or poor yield. As long as you prepare the seeds and the system properly, root vegetables should thrive hydroponically under the right conditions.
Here are the problems you should expect though.
- Power outage causing the pump to stop working
- Wrong lighting i.e using fewer lights for the space or lower wattage
- Malfunctioning system equipment
- Failure to clean and maintain the hydroponic system causes it to clog
- PH imbalance that causes blocks the plants from absorbing nutrients
- Nutrient deficiency
- Temperature issues i.e the greenhouse is too hot or too cold for the plants.
Conclusion
Root vegetables like potatoes, onions, radishes, carrots, and beets may not be the first thing that comes to mind when you think about hydroponics but they are a great option. These are plants that otherwise rely on suitable weather to survive and struggle with pests and diseases. Hydroponic systems solve all these problems and allow you to enjoy your favorite vegetables all year round.
