Three sisters planting is an ancient “new world” method of growing vegetables that work extremely well together. Native people of the new world were basically performing what we, today, call “companion planting”. Companion planting is a style of gardening that takes into consideration what plants do well together (and which do not). There are a few books on the subject to help you get some of the basic concepts down:
Native American Gardening: Stories, Projects, and Recipes for Families
In Tucson, start your own three sisters garden sometime in March when the threat of frost is well away. You may have to use some tricks to get an early start on long-season varieties like Tahitian squash. Make sure the bed is well-nourished with nice layers of compost, and composted manure.
The tradition in much of the US is to plant the crops on small mounds. This is not advisable in our dry, hot climate, as the mounds tend to dry out too fast.
- Corn is planted at about 6 inches apart in a group, like a small circle. At this point you can let the corn grow to about 4 inches tall. Or, if you are like me and like to get it done quicker, you can plant the other sisters right away. What you will have to keep in mind is that when the crops grow, make sure they are not shading each other out. The corn needs a chance to get growing higher than the beans. But if you just watch the crops and move the beans away from the corn at first, you should be ok.
- Plant beans between the corn. This will put the beans about 3 inches away from each corn stalk.
- Next to your planted corn/beans group, make another grouping of squash, planted in a triangle. Seeds should be about 4-6 inches apart.
- Alternate groupings corn/beans and squash.
- As I often preach on this website, mulch the hell out of your garden. Thick mulch protects plants, and decreases your need to water. Use a few
different layers: a compost layer, and a layer of straw over the top. Apply the mulch once the seedlings have sprouted and be careful not to bury the base of the plants too much with the compost. I have posted instructions on mulching here. You don’t have to follow them exactly, but just get the general concept down.
- Vary this concept by replacing the squash with pumpkins and melons. You can also play with different varieties of beans, keeping in mind that if you want to collect seed to grow for next year, keep varieties of the same crop far away from each other.
The basic concept here is that the beans grow up the corn stalks, the squash acts as a living mulch around the base of the corn stalks, and the corn provides a general protected medium for it all to occur. Some people say that the prickliness of the squash keeps some critters away, though I have doubts as to how effective that really is (ever meet a javalina?). In general you end up with a wall of food-producing plants that grow very well together.
Growing beans always improves the soil, encouraging biology that increases the nitrogen availability in the soil. If you follow the concepts of avoiding compaction in the garden, mulching, and layering in the soil, you will find these crops do a great job of furthering biological development in your soil. When you harvest, be careful to avoid digging it all up. Pull up plants and shake the soil off the roots.
I avoid turning the remaining plant debris into the soil because I don’t like to disturb the fungal development in the soil, and I also don’t like the worms to get chopped up. Soil will naturally aerate itself, and nutrients will naturally seep down into the soil via the biology and gravity of the situation. Let nature do the work, and feed organically from above. You don’t have to do things this way. But it is the way I have found to be the best for me.
Renee’s Garden offers a Three Sisters Garden seed packet that contains the seeds and instructions for planting your own, if you want a good starter for a beginner.