Growing a Three Sisters Garden

The Physicians Committee

Growing a Three Sisters Garden

A Three Sisters garden is fun to grow and educational for both children and adults.

A 10-by-10-foot garden is a perfect size. You can use a smaller plot, but your yield will be less robust. Corn is a social plant; it needs at least a small group in order to pollinate.* Choose a spot that has full direct sunlight—at least six hours per day. Soil should be loose (not packed), with a neutral pH (6.0 to 7.0).

Corn: Sweet corn is delicious, and its outer hulls are tender and perfectly edible, which is why home gardeners vote for it hands down. You can also grow popcorn, if you like.

Typical sweet corn varieties are divided into three main genetic types:

  • Traditional or “sugary” varieties (indicated by the letters “su” on the seed packet) are yellow, white, or mixed.
  • “Sugar extended” or “sugary enhancer” (se) varieties maintain their sweetness longer, both while growing and after harvest. As a result, they are often preferred by home gardeners, although they require warmer temperatures at germination, compared to the other types, making them a bit more challenging to grow.
  • “Extra sweet” or “ultra sweet” varieties have shrunken kernels and are labeled “sh2.”

The seed packets will let you know how long they take to mature. So if you live in the far north, go for a short-season variety. Further south, a longer-growing variety will work. If you are new to gardening, disease resistance will be important than it is for experienced gardeners, who are more comfortable in spotting and treating potential problems.

Beans: You’ll want pole (also called “runner”) beans, rather than bush beans. As their name implies, pole beans are ready to run up trellises and corn stalks. Common pole beans include pinto, black, kidney, and navy beans. Green beans and lima beans come in both pole and bush varieties. Soybeans are bush beans.

Squash: Summer or winter squash both work well, as do pumpkins. Summer squash are ready to eat in six weeks. Winter squash take longer, from 2 1/2 to four months. Here are popular varieties:

Summer Squash

  • Crookneck squash
  • Straightneck squash
  • Zucchini

Winter Squash

  • Acorn
  • Butternut
  • Buttercup
  • Hubbard, blue hubbard, golden hubbard
  • Spaghetti squash
  • Cushaw


You’ll find seeds at your local gardening store and online. Organic seeds are available, too.

Preparing the Soil

Clear away any weeds and stones. Add a few inches of compost, turning it into the soil and loosening the ground. Water the ground generously.

You can plant your garden as soon as the night temperatures are up around 55 degrees Fahrenheit, although se and sh2 corn varieties require slightly warmer temperatures. If you plant as late as early June, you’ll still have plenty of time for an autumn harvest.

To prolong your corn harvest, you can plant a mixture of varieties that vary in their growing times. You can also plant part of your garden a bit later, provided you have enough plants maturing at any given time to allow pollination.

Your Garden Layout

There are many variations on a Three Sisters garden layout. But all of them plant corn in clusters, rather than a single row. The reason is that corn is wind-pollinated (pollen from male tassels must make contact with female silks), so plants do better in close proximity.

Here is a traditional planting pattern I learned:

Diagram of planting corn and bean mounds

In a 10-by-10-foot garden, mark off three rows, 5 feet apart. Each row will include five mounds, with corn/bean mounds alternating with squash mounds in a checkerboard pattern. Mounds drain better than flat soil. Each should be 18 inches across, with a flat top.

First, plant the corn in the middle of the each side of the square, as shown, about one inch deep. Within about two weeks, the corn plants will shoot above the surface. Once the corn is about 4 inches high, clear the garden of any newly arrived weeds, and plant bean seeds, about one inch deep, at the corners of each square.

At the same time, you can prepare the squash mounds. They look just like the corn/bean mounds, but have only three seeds each, planted in a 4-inch triangle.Diagrams of spacing corn, beans, and squash in mounds

Bean Debutants

If beans have not been planted in your garden before, dusting dampened seeds with an inoculant of rhizobial bacteria before planting will boost your harvest. The word “rhizobial” comes from the Greek “rhiza,” meaning “root,” and “bios,” meaning “life,” referring to bacteria that live symbiotically in the roots of legumes, such as beans and peas. These bacteria transfer atmospheric nitrogen to the bean plants, which give them plenty of nutrients in return. Inoculant powder is available from nurseries and seed companies. These helpful bacteria will remain in the soil, so you can skip this step in future years.

Weeding and Watering

Eventually, the squash leaves will shade the soil and inhibit weed growth. Before that point, your plants may need a bit of help in staying clear of weeds.

In weeks where there is no rain, be sure to water your garden thoroughly, especially as the corn tassels and silk appear and the ears mature. If the corn leaves start to curl, that is a sign of insufficient water. A lack of water during silking and pollination can cause your corn ears to fail to fill out all the way to the tips.

When you water your garden, aim at the ground, not the plants. Wet bean plants are more disease-prone. After a rain, let plants dry before working them. And do not overwater; the idea is to moisten the soil, without flooding your garden.


About 20 days after the first corn silk strands appear, the ears should be firm and the silks will be dry and brown at the ends. Kernels should be smooth and plump. Slice open an end kernel with your thumbnail; the juice should look milky. This is the “milk stage,” which is when you want to harvest your crop (if the juice is watery, it’s too soon, if it’s doughy, it’s too late). This stage lasts less than a week.

You’ll harvest one or two ears per plant. Snap off the ear with a quick downward, twisting motion. For the best taste, sweet corn should be eaten or refrigerated promptly. Husk it just before cooking.

Green beans should be harvested when the pods are still slim and tender. You can harvest field beans (i.e., regular beans) once until the pods are well filled out but have not yet turned brown. They will continue to produce for a month or two. As you pick them, avoid damaging the vine. For dry beans, leave the pods on the vines for as long as possible. When mature, the pods are dry and the beans are quite hard. If you would like to hurry the drying process along, you can pull up the vines and leave them in the sun or hang them up to dry.

Summer squash can be harvested once the fruits are about two inches in diameter, but do not wait too long. They are best when small and tender, with soft skin that can be easily cut by your fingernail.

Winter squash can be harvested once its skin has hardened thoroughly and has a dullish look. Cut the stem with a sharp knife about 3 or 4 inches from the fruit. Leaving a bit of stem attached keeps the squash fresh. Set the harvested squash in the sun for a few days so the stems can dry, then store them in a single layer, not touching each other (crowding promotes decay).

Harvest plants when dry; working with wet plants can spread plant diseases. After harvest, the remaining stalks can be cut up, removed, and composted. Don’t leave them in place, or you are likely to start a nursery of insects who will compete with you for next year’s crop.


Harvest Pudding

 Smashing Corn Casserole (from Christina Pirello)

This truly deluxe casserole is a snap to make and a hit with everyone who has tasted it. It blends the sweet taste of fresh corn, tangy roasted red peppers, rich sesame tahini, sweet squash and the nutritional kick of beans.

1 cup cooked black beans, smashed with a fork
1/3 cup sesame tahini
soy sauce
yellow corn meal
spring or filtered water
2 ears fresh corn, kernels removed
several clean corn husks
1 red pepper, roasted and diced
2 cups (approximately) pureed pumpkin or winter squash
pinch sea salt

Puree the beans with tahini and season lightly with shoyu. Set aside. Mix corn meal with salt and enough water to make a thick paste. You will need about 1 1/2 cups of this mixture. Fold in corn kernels. Set aside. Line a lightly oiled, deep casserole dish with several clean corn husks, allowing them to hang over the sides a bit. Begin layering (like lasagna) by spreading some corn meal mixture on the husks. Add some of the bean mixture, pureed squash and sprinkle with a bit of the red peppers. Continue layering until the dish is full, but be sure to end with corn meal on the top. Fold the husks over the casserole and press into the topping to hold them in place. Cover and bake at 375 degrees for 35 minutes, until firm. Remove the cover and return to oven to brown the top slightly. Serve immediately.