I will grow the following vegetables in a big square area. How much depth is required to prevent root damage and non-vertical root growth? Note that I will grow them indoors.

  • Carrot
  • Arugula
  • Brocolli
  • Chard
  • Collard greens
  • Garlic greens
  • Lettuce
  • Ginger

3 Answers 3


Ginger is perennial, so I'm not sure it is good to grow it indoor. But I never cultivated it, so I don't know.

For the other vegetables, I think around 30 to 50 cm should be enough. Most could live with less ground, but I would have some extra space to help not to over-water (and under-water) the garden.


Of the plants you list, the Carrots are probably your biggest depth-desiring crop, Chard will be a close second. The chart on this page suggests a minimum depth of 18-24 inches (45-60 cm) for chard or carrots. I would expect the carrots to be the first plant to notice over-shallow soil. The root that you're actually eating might only be 8 inches, but the fine roots off the tip go down much further than that.

  • No they don't, sweetie. The feeder roots feed the carrot and they stay up where they can access the water and organics within the top 4 to 6" of soil. Roots don't want to grow DOWN where the action just ain't happening. There is so very much more going on here than depth of soil.
    – stormy
    Nov 30, 2016 at 20:22
  • So you are going to argue that everything below the tip of the carrot you're eating is unnecessary for the plant to grow? Dug up carefully I've seen the tip on root veggies grow better than a foot past the end of what you'd eat. The plant just grows that root-mass for the fun of it?
    – GardenerJ
    Nov 30, 2016 at 20:25
  • Yup I am in this case. I don't think we are talking carrots to carrots here. I am saying that that carrot is not involved in any important way in the uptake of chemicals and water. It is a storage organ that is capable of bending to go around a rock for instance. I am talking about everything else that is necessary to make one's own garden on a roof, a balcony, a garage driveway. Carrots are a storage organ we can eat. For the plant to survive until the next spring (depending on the zone involved). Yes that plant is creating more carrot for the health of itself..for its survival.
    – stormy
    Nov 30, 2016 at 21:50
  • Oh and by the way GardenerJ, carrots that are stubbier, fatter than longer are BETTER. Lots of different varieties there. I think using pots is far easier, more controlled than trying to make a chunk of garden over concrete or whatever...and using garden soil is just not going to work. Why improve on the 'pot' with a drainage hole where you can control the specie grouping for needs, the drainage, the neighbors, to allow people to enjoy the space as well...with good old fashioned pots?
    – stormy
    Dec 1, 2016 at 20:57

What is your set up? I am assuming you think you can dump 12" over concrete and get away with that for a garden? A vegetable garden doesn't need depth of soil in the GARDEN. Most roots to include carrots and other root crops don't need any more depth. That is not the problem.

95% of all plant roots or something close to that percentage are found in the top 4 to 6" of the surface, top horizon of the soil. That is where the chemicals and water necessary to provide the little chlorophyll factories in the leaves/stems to make food for the plant reside. Below 6 -12" is subsoil, has little organic matter, proper chemicals and little water makes it down that far for plants to need to expend the energy to grow roots that deeply. We aren't talking about support roots some plant have.

I am assuming you are making a big square POT for growing vegetables. Drainage is an issue. Using garden soil for this POT is another issue. Sun is an issue. Orientation to sun and wind is an issue. Is this outside on a balcony or a patio or is this inside or out of doors. Are you going to try to use rock/gravel at the bottom for drainage? We need to talk about an awful lot more. Otherwise I am just assuming. Please answer; 1) drainage 2) type of soil and that HAS TO BE STERILIZED POTTING SOIL NOT GARDEN SOIL 3) is this indoors out of doors over concrete what are the sides to be 4) what is the lighting? Wattage if you are using artificial lighting or sun orientation and zone if this is grown out of doors. Where is the excess water to go? Drain to?

All of these plants do just fine in POTS with sterilized potting soil with proper drainage no perched water table created by using rock or gravel beneath the soil, artificial true growing lights or decent sun exposure and of course the proper amount and formulation (s) of fertilizer and attention to pH.

Some on your list need higher N than P and K. The leafy stuff you don't want going into reproductive growth. Some of those plants need lower N in relationship to the percentages of P and K. Using fertilizer in pots and confined artificial garden spaces it is more important to be precise. Just a little too much and you will kill your plants. You will have to separate the plants; root crops (carrots), leafy vegetative crops (Chard, lettuces), reproductive crops (broccoli) as each need a different formulation of fertilizer.

pH is important, perhaps not so much with your list but keep this chart around; enter link description here

Sorry to be such a stick in the spokes but you don't want to fail and have to learn the hard way. We care about making the first experience for a newbie gardener a good experience.

  • And I finally read you are growing INDOORS. You need serious lighting make no mistake. Don't go out and do the MARTIAN thing!! He had no other choices...Matt Damon had sterile soil that is for sure. No drainage but he had only so much water to meter out to each individual plant. Potatoes are one of the toughest plant I know. And poop ain't an entire fertilizer formulation. If you haven't read the book The Martian, you should it is very real except for that dang windstorm at the beginning. That was a farce. Depth of soil here has no bearing unless a lot of other factors are addressed.
    – stormy
    Nov 30, 2016 at 21:58

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