By Suzanne Seryck, Master Gardener
I have just finished cutting back my lupins for a possible second bloom, scattering their seeds and transplanting baby lupins that have popped up in all the wrong places.
Lupinus, or more commonly known as Lupins, are one of my favourite plants especially in the late spring when they are first in bloom. I tend to lean towards plants that need little to no care, that will attract insects, will self seed but are not invasive, and that give me joy when they are in bloom. Lupins fit that category for me perfectly.
Lupin is a genus of flowering plants in the legume family Fabaceae, along with peas and beans. They have been grown since the days of the ancient Egyptians and were eaten by the Romans. Lupins like well drained soil, preferring sandy soil, but in my garden they grow well in clay. They grow in either sun or partial shade conditions. I will often let some of the flowers on my plants go to seed, self-seeding throughout the garden. But depending on where they decide to grow, I tend to transplant them and move them around. When digging up a lupin, take care to dig up the large tap root. I prefer to dig them up when they are very small, so I don’t damage the root any more than necessary. I also find it easier on both me and the plant to transplant them into a pot, rather than directly in the ground. This enables me to keep the plant in the shade for a few days, water more often and just baby them along more.
For me, lupins in my garden tend to be short-lived perennials, lasting anywhere from 3-5 years. They do not grow true from seed so to ensure that you have a true seedling you should take basal cuttings. A basal cutting is best done before the plant has flowered; you cut a shoot close to the root, take off all the leaves, nip out the top of the cutting and then transplant into a pot filled with compost and soil. When you see roots coming from the bottom of the pot, you can then transplant the lupin into your garden.
Because lupins are members of the legume family they are nitrogen fixer plants. Using a specific bacteria, ‘rhizobia bacteria’, that allows them to draw nitrogen from the air, convert and then store the nitrogen in nodules that grow on their roots. The nitrogen can become available to other plants in a number of ways. If a nodule breaks off and decomposes, the nitrogen becomes available in the soil and when the plant dies or if the plant is tilled back into the ground, the nitrogen also becomes available. In addition, lupins have a large tap root that is great for breaking up compact soils.
Most of the lupins you buy in garden centres are not native to Canada, as there is a native lupin–the wild lupin or Lupinus perennis which is considered native in Ontario. It is normally blue or purple and prefers a dry, sandy soil, but will grow in any well-drained soil. Wild lupins are often used in restoration projects because the large tap root helps to control erosion. It is also essential to the endangered Karner Blue butterfly which feeds exclusively on it and is a host to other butterflies. If you want to add this plant to your garden, you are best to buy the seed from wildflower farms and ensure you follow the instructions carefully as the seeds need specific conditions to germinate.
An example of a wildflower nursery selling the seed is given below: