As an example, I got an email today from Crocus telling me that they are offering Verbena Bonariensis plants for £8 each. Now it happens that a clump of about thirty of these plants has self-seeded in my borders, so I’ve saved £240 right off, plus all the hastle of planting them out.
My borders are full of other self-sown plants. They include the magnificent Angelica (pictured here), Crambe cordifolia and the tree spinach (Chenopodium gigantic), which grows to five feet in height and, very helpfully marks itself out as a young seedling by having a splash of purple on the tops of the leaves. Tree spinach also transplants very easily, which is helpful if you want to create a clump, which can look very impressive. All these plants self-sow freely, so once you’ve bought one packet of seed, that’s all you’ll need in a lifetime.