Sacre Bleu kidney beans
I haven’t started, let alone finished, my final vegetable review (but you can read part 1 and part 2). Yet, I started planning this year’s garden months ago! This frosty winter passed slowly and then all at once. I spent many snowy days planning a client’s landscape. With permission, I am writing about our design. We are planning on two garden beds: one with corn, squash, and beans, and the other with peppers, potatoes, tomato, and herbs.
The benefits of “three sisters” agriculture
My client requested a “three sisters” garden bed, or “milpa.” Native Mesoamerican people designed this strategy, which optimizes the harvest of three mutually beneficial crops: corn, squash, and beans. People must harvest a milpa by hand. Because of this, it is not suitable for mass-scale industrial agriculture. “It takes five people four days to pick the beans and harvest the maize” for a one hectare plot (Landzettel, 2026).
However, it is a sustainable and productive system that deserves more attention. The milpa has high value for food security gardening. Growing the three sisters together creates climate resilience through mutually beneficial interactions between the three crops.
Pungo Creek Butcher Dent Corn seed packet from Southern Exposure Seed Exchange
Each plant plays a role so that the garden stays healthy. The beans “fix” nitrogen from the air into the soil, where plants can absorb it. The corn provides a pole for the beans to climb, and the squash’s large leaves cast a cooling shade on the soil (Landzettel, 2026;Kruse-Peeples & Marinaro 2016). These mutually beneficial interactions are what make the milpa so wildly resilient!
A milpa can have mounds or rows. Kruse-Peeples & Marinaro (2016) report that the traditional Iroquoian way to build a milpa is by making mounds, which we will emulate.
“Other sisters” are also important to southwestern Native cultures, and can grow in a milpa (Kruse-Peeples & Marinaro, 2016). For example, we will grow melons alongside our squash.
Using lasagna mulching to build soil
No-till techniques help the soil stay healthy because they disturb it less than digging it up. We will use “lasagna mulching” to create two garden beds with mounds. Lasagna mulching is layering composting materials on top of existing soil (Rauter & Sherp, 2025). We will layer compost between cardboard to create mounds. On top of this we will add mixed coco coir and compost. The cardboard will be inoculated with oyster mushroom grain spawn, which will integrate outdoor mushrooms into the garden bed.
My client and I are totally thrilled about this design! This mound-based intercropping design is taking shape well. I would love to repeat this design in the future. Hopefully this summer, we will have a green and growing garden brimming with vegetables and mushrooms. Stay tuned to follow this project as it grows!
Oyster mushroom grain spawn
Bibliography
Landzettel, M. (2026, February 13). Milpa. How an Ancient Farming System Helps Small Farmers in Today’s Mexico. Slow Food. https://www.slowfood.com/blog-and-news/milpa-ancient-farming-system-mexico/
Kruse-Peeples, M. & Marinaro, L. (2016, May 27). How to Grow a Three Sisters Garden. Native Seeds/SEARCH. Native Seeds/SEARCH. https://www.nativeseeds.org/blogs/blog-news/how-to-grow-a-three-sisters-garden
Rauter, S. & Sherp, L. (2025). Sheet mulching and lasagna composting with cardboard. Oregon State University Extension Service. https://extension.oregonstate.edu/catalog/em-9559-sheet-mulching-lasagna-composting-cardboard