Companion planting is a great technique for a successful gardening. There are many combinations of garden plants that work well together including onions and potatoes. Here’s why!
What is Companion Planting? How does it work for Potatoes and Onions?
Companion planting takes advantage of complementary plants that can offer each other benefits to aid in their growth. There are a few ways that companion planting works.
- The plants can be complementary in soil resource uses. Meaning that what one plant needs is not necessarily what another one needs. The two plants use different resources in the soil and don’t take away from one another. Also the ideal plants tend to be in the same ballpark when it comes to soil acidity.
- Some plants have pest control properties that prevent insects from noticing or bothering either plant in the vicinity. One plant may mask the other plants and “camouflage” them from predatory insects or creatures.
- Companion plants are usually compatible when it comes to water needs. They will typically be able to tolerate the same comditions.

The Soil
With potatoes and onions as companion plants you have a mix of characteristics that work well together. Potatoes need a deeper root system and will typically go 6-8 inches under the soil. Onions really only need planted about an inch deep, or the depth of the onion seed bulb. This enables the potatoes to seek their nutrition from deeper in the soil while the onions just take from the upper layers.
Common Pests
As for pest control benefits onions can ward off potato beetles which are a common issue with potatoes. My biggest concern this year are voles in the garden and onions can help to ward them away. Voles are rodents that love to eat the roots and tubers from under the soil’s surface. I’ve had sweet potato crops decimated by voles so it is a big concern I have. Onions are not something that voles typically enjoy so by planting onions and potatoes together I can hopefully shield my potatoes against the voles.
Soil Acidity (pH)
The soil acidity for each of these vegetable garden plants is compatible as well. The ideal pH for this duo is around 6.0. This bridges the low end of onions (6.0-6.8) and the higher end of the potatoes (5.4-5.9). It’s not absolutely perfect but is close enough to work!
How I Planted Potatoes and Onions Together
My plan for the potatoes and onions was to use this firepit I bought from Tractor Supply Company (affliate link). I bought it several years ago and have always used it as a raised bed, in fact I have two of them. I planted the potatoes in the center and a “ring of onions” (not to be confused with onion rings, that comes later) near the edge of the firepit. You can see the whole process in the video just below the image.

Potatoes are onions are just a couple good companion planting combinations. My favorite probably being basil and tomatoes! They don’t just taste good together!
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