The Three Sisters

Corn is possibly the most domesticated organism on the planet (aside from us!). Archeologists have identified domesticated corn as old as the oldest identified human settlement in the Americas, but only recently identified its wild parent, teosinte, through genetic testing.

On first planting corn in small gardens, a lot of gardeners, knowing what corn looks like on an industrial farm, make the classic corn newbie mistake—they plant a row of corn. However, in a small backyard, you can’t plant corn in rows. Because corn is wind-pollinated, when planted in a single row it risks going unpollinated.

Enter the Three Sisters, which is corn, beans and squash, planted together. It is a traditional First Nations companion planting technique (planting compatible plants together), using the attributes of each plant to strengthen all three. This is the grandmother of companion planting. Some plants go well together –carrots and onions love everybody; strawberries love borage; and of course the Three Sisters. Just google “companion planting” to find examples.

Some reasons to companion plant: nutrient enrichment, pest control, mechanical. (Um, mechanical?) Back to the Three Sisters: the beans are there because they restore nitrogen to the soil. But the corn and the squash also have “mechanical” purposes– the corn stalks act as bean trellises, and the squash acts as a mulch, keeping the weeds down.

Three sis photo reduced

Here’s the How To:

Corn
There are three types of corn, based on the moisture content of the kernels, and the end use. For a backyard garden look for sweet corn or popcorn. Corns listed as dent corn or flint corn are for grinding. These are also suitable for backyards, but because corn is a low-yield plant (2 to 5 ears per stalk is not unusual for non-industrial varieties) you need an awful lot of it to get enough cornmeal for practical use.
• Make a mound, about 12 to 15” across. Corn will send out “adventitious” roots; these are roots that crow from the stalk, sideways into the soil, strengthening the plant (I call them “corn feet”).
• Plant seeds or starts (corn starts shouldn’t be taller than about 5”) around the ring, about a hand span apart.
• When you plant corn in a raised bed or other small area, it needs to be very dense to pollinate properly.
• Corn can be planted anytime from early May to early/mid June. Best are varieties that mature in 85 to 110 days.
• Corn is ripe when the silks are very dark and a little dried-out looking. You can tell corn has been properly pollinated because the silks will turn pale pink, and then gradually a deep mahogany.

Squash
• Plant seeds or starts directly into the center of the mound. Plant up to three, and then thin them when the plants are about three weeks old, to get the strongest plant.
•It’s best to plant out squash after June 10, even seeds, because late May and early June is when the squash vine borer (SVB) moths lay their eggs.
• In small gardens, you’ll want to train your squash. In large gardens you can let it go crazy.
• Squash will be the last thing to get ripe. While you can use summer or winter squash make sure summer squash is a vining variety like Pattypan, not a bush one like zucchini.

Beans
• Plant pole bean seeds directly when the corn is 8” to 10” high. If you plant your beans too early, it will get taller than the corn very quickly.
• Purple beans, with purple vines, are easier to see on the green corn stalks.
Variations:
• If you have SVB then you shouldn’t plant squash for two years. Use bush beans as the third sister.

The Fourth Sister
Cleome, or Spider Flower, can be planted with the three sisters. This beautiful ornamental is high in pyrethryum and acts as a natural pest repellent.

A note about corn and squash in community gardens
Because corn is wind-pollinated, there is a risk of cross-pollination from other corn plants within a quarter mile (about four football fields). In addition, corn is very susceptible to aphids, which resist removal unless you have access to a high pressure spray. You cannot spray even gentle organic insecticides on corn as it weakens the fibers and makes the plants fall over.

Squash is also problematic in community gardens, again because of pests. If you plant squash, do your neighbors a solid and be extremely vigilant about pests.

You can find three Three Sisters plots in the Grow2Give area at Hello!Howard- in the central “diamond” beds, along Howard street and along the alley.