Pat Munts: Sweet potatoes and peanuts need warm soil, weather

A while back I wrote about a couple of growing experiments another gardener and I at the Resurrection Community Garden were trying: sweet potatoes and peanuts.

Now that the plants have died down, we can give you the results: Is it possible to grow these southern treats in Spokane?

The answer is maybe, but it’s going to take some serious season extension efforts to do it.

Both peanuts and sweet potatoes like lots of warm soil and weather to grow well. Unfortunately Spokane lacks both in the late spring and early summer. The soil temperatures in late May were in the 50s. June’s temperatures stayed pretty cool. So my sweet potatoes just sat there and tried to grow a few leaves. Both the peanuts and the sweet potatoes were planted in raised beds which helped, but there just wasn’t enough heat to get them going.

July and August were more to their liking. July had more 90-degree days than normal and August wasn’t too bad either. So the sweet potato vines finally got started and were soon crawling through my tomatoes. But as is often the case, the weather began cooling off in September and the plants slowed down. Frost nailed both of them at the beginning of October.

Upon digging, the sweet potatoes yielded a handful of skinny roots that I think I’ll add to the Thanksgiving feast. The peanuts produced four “pegs” that managed to insert themselves into the ground but yielded no nuts. As a legume, the peanut’s best contribution to the garden may well have been that they added nitrogen to the soil – not a bad trade off.

So experimentation must continue. Next spring, I am going to buy the sweet potatoes early and plant them indoors in pots so they can get a start. In the garden, I will dig a deep bed next to the south wall of our shop and fill it with fresh manure topped with soil. Called a hot bed, this will make for a much warmer growing spot early in the season as the manure composts and generates heat. Being close to the wall, the soil will warm up quicker and stay warm into the fall. If anyone wants to join the experiment, let me know and we can compare notes.

As I write this, the weather report calls for a bit of wind and rain that will probably bring down the beautiful leaves we have been enjoying for so long. This will be a good time to gather a bunch of them up and store them to make compost next year when there is more green material to mix in. Pile them in a corner and cover them with a tarp. You can also shred them up with the lawn mower and mulch your flower and garden beds. They will help keep the chickweed and bulbous bluegrass from getting too much of a foot hold over the winter. A foot or so of shredded leaves makes a great mulch for tea roses and tender perennials.