I’ve got to tell you all, I’m ecstatic when I get messages from Epic Gardening readers. I LOVE opening up Gmail during a break from business and seeing urban gardening questions come in, so you better believe I was excited when a reader hit me up and asked a great question about plant spacing. She’s setting up a small hydroponic herb build and wanted to know how she should space her plants.
Replacing Soil With Hydroponics
The question, “What do I need to know about plant spacing in hydroponics?” is a tough question to answer unless we understand a couple simple concepts first. Once you have a grasp on these ideas, it’s going to be very simple for you to figure out how to space out plants in your hydroponic garden!
Root Development
In soil, plants need ample space for their roots to seek out nutrients. Soil does a few things for plants:
- Provides stability
- Provides pockets of oxygen
- Retains water
- (Hopefully) full of nutrients
That’s a lot of work for soil! When we switch plants to a hydroponic environment, we have to replace all of those requirements with just two ingredients: nutrient solution and growing media. The nutrient solution takes care of three: oxygen, water, and nutrients. The growing media provides the stability.
Hydroponics holds an advantage over soil in that the roots are bathed in highly oxygenated water, meaning that they do not have to do a lot of work to seek out the ingredients for growth. This means that roots can be intertwined and intermingled in your nutrient reservoir without too many consequences…as long as you don’t clog your system or cause any other system malfunctions!
Vegetative Growth
Some plants are just smaller than others. In soil, this means that you can group them closer together than other plants. For example, onions can be planted extremely close together because they don’t produce a lot of foliage, and the foliage they do produce generally grows vertically. Now let’s take a look at something like broccoli, which grows a central flower that is surrounded by a lot of large leaves that fan around the flower. Not the best plant to grow if you’re trying to maximize yield in your garden.
You need to roughly follow the instructions on the seed packet for whatever plant you’re planting in hydro.
Plant Training Techniques
Because plant growth is accelerated in hydroponic gardening, you have the opportunity to quickly train your plants to grow in certain ways. This is very similar to using tomato cages in soil gardening to encourage vertical growth vs. horizontal sprawl. There are a number of ways to achieve this in hydroponics, some of the most popular being horizontal screens or vertical tying. If you can take a plant that normally sprawls out horizontally and grow it vertically instead, you’ll be able to squeeze more of them in close proximity to one another.
Go Forth And Plant!
As we come up on the new year, I hope that this basic plant spacing guide for hydroponics is helpful. If so, let me know what you’re going to be planting in the new year in the comments! I’d love to hear about it 
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Kevin is the creator of Epic Gardening, a community dedicated to teaching urban gardening, hydroponics, and aquaponics. He enjoys skateboarding, piano, guitar, business, and experimenting with all kinds of gardening techniques
Kevin, this is a good blog that covers a very important subject. I have lost count of the number of growers I have spoken to who have lost yield due to poorly planned spacing, especially the newbies to Hydroponics. Considering the space your plants will need is fundamental in the success of your crop and the eventual yield.
Newbie growers, and even seasoned growers that have made the change from soil or cocoa mediums to Hydroponics tend to squash too many plants in too small a place, over crowding your plants will have serious implications through out the duration of the grow cycle. Apart from the fact that crowded plants give a lower yield they are also more at risk of diseases such as blight or mold, whose spores thrive in these crowded conditions.
I would say that plants grown hydroponically need more space than soil bound, this is how I explain it to newbies,
If you look at a soil bound plant that is well cared for as an average man who visits the gym a couple of times a week, a hydroponically grown plant is like that same man being trained up to the fitness level of an Olympic athlete, its a good thought. Rule of thumb is about a metre sq. depending on the plant species.
Hope this adds value to what is a good post already. Jp
Thanks JP!
I’ve made that mistake before, so I figured that I would write up a post about it. It’s a really popular question for newer growers. I’d agree that most of the time they need more space, but there are a few unique situations where they need MUCH less space as well.
Thanks for the comment and cool site…just checked it out!