The Walden Effect: Farming, simple living, permaculture, and invention.

Plant spacing and vegetable roots

11 week old winter squash - roots reach 25 feet in diameter.The obvious method to prevent bare soil in a vegetable garden is mulch, but unless you shell out the cash for a dumptruck load or two, chances are there won't be enough to go around.  How else can you protect your soil?

Close plant spacing can shade your soil surface, preventing damage to the underground ecosystem while also keeping weeds from growing.  I often plant my lettuce and leafy greens far closer than the instructions on the seed packet recommend.  The result is an endless carpet of green food, with little weeding after the vegetable seedlings catch hold.

Depth (ft.)
Width (ft.)
Asparagus 4.5 10.5
Beans, kidney 3-4 2
Beet 10 2-4
Cabbage 4-5 3-3.5
Carrot 6-7.5 1-2
Cauliflower 2-4 2-2.5
Corn 5-6 1.5-4
Eggplant 4-7 4
Garlic 2.5 1.5
Horseradish 10-14 2-3
Kohlrabi 7-8.5 2
Leek 1.5-2 1-2
Lettuce 4-6 0.5-1.5
Okra 4-4.5 4-6
Onion 1.5-3 0.5-1.5
Parsley 2-4 1.5
Parsnip 6.5 4
Pea 3 2
Pepper 3-4 1.5-3
Pumpkin 6 13-19
Radish 2-3 1-2
Rhubarb 8 3-4
Rutabaga 6 1-1.5
Spinach 4-6 1.5
Squash, winter 6 13-19
Swiss chard 6-7 3.5
Tomato 3-5 2.5-5.5
Turnip 5.5 2-2.5

Close spacing does have its limits, though.  I've learned the hard way that tomatoes need lots of air circulation in our climate to prevent blight --- Kourik recommends planting them four feet apart.  In addition, roots of our garden vegetables are much larger than I'd ever suspected --- carrot and swiss chard roots reach seven feet deep while pumpkin roots can grow horizontally to 20 feet in diameter.  Without double digging and heavy amendments of compost, roots of these plants will compete with the neighbors and both will struggle.  Check out the amazing root diagrams in John Weaver's Root Development of Field Crops (available free online) for more information.

Roots of a 10 year old horseradish reach 14 feet.


More fascinating tidbits from Robert Kourik's book are coming next week.  If you can't wait, check out his blog.

This post is part of our lunchtime series reviewing Robert Kourik's Designing and Maintaining your Edible Landscape Naturally.  Read all of the entries:

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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