The Truth About Thistles: A Permaculture Revelation

Since May, I have been watching videos for my online permaculture design course (PDC). It’s a slow process with the busy-ness of summer, but I am about halfway through and the design deadline has been pushed back to the end of September. Whew!

There are two dvds dedicated to soil. TWO! When I saw that I thought I would surely fall asleep during those videos, but the “life” of soil is strangely fascinating. Especially fascinating to me was the video I watched last night on pH. Geoff Lawton, the professor of the course, was making a “supermarket” analogy to explain soil pH.

He drew a birds-eye view of a supermarket. Each aisle was a mineral or nutrient: Zinc, phosphate, potassium, nitrogen, copper and iron. The shoppers were all of the plants that need different nutrients. As all of the plants crowded in to shop for what they needed, the aisles got blocked so that all of the plants were not able to get in and get what they needed.

Enter the thistle.

Now, we have an abundance of thistles. I’m constantly pulling, cutting and cursing them. So naturally, my ears perked up even more.

The thistle loves acidic soil, or soil rich in copper and iron. Wait. What? We have very alkaline soil, how is it we have so many thistles? Wait for it.

The thistle has a deep tap root so it can dig down much farther than the other plants, weeds, etc. So when the store aisles are blocked and the plants that need iron and copper can’t get it, the thistle knows another way in the store.

It’s not necessarily that the soil is deficient in iron and copper, maybe they are just being blocked out. The thistle, knowing all the secret pathways, can dig down past the block and find the iron and copper and bring it on up to the top of the soil

Does this mean we should just let thistles run rampant on our property? No, that would lead to too much of a good thing. The key, I’m learning, is balance. Soil is a living being that needs tended to just as much as the plants in your garden.

The answer? Chop and drop and compost…removing seed heads of course.

There are other problems with our soil and other areas where it needs to be repaired and amended, but I am a little relieved to find a relatively easy answer to our acidity problem.