I absolutely love lupins – their vibrant, upright flower spikes really stand out in the garden. The good news is that it’s quite simple to sow them, as long as you keep a few tips in mind. I usually grow perennial lupins (Lupinus polyphyllus) in my garden, but annual lupins also work well. You can either sow them directly into the bed or plant young pre-grown plants.
Contents
Lupins Sowing: The Essentials at a Glance
For perennial lupins, I can sow them directly into the bed in May or August, or I can start them off in pots in April. To help the seeds germinate better, I roughen the tough outer shell with sandpaper and soak the seeds in water for 24 hours before sowing them.
When Should I Sow Lupins?
I usually sow perennial lupins in May or August directly into the bed. These will likely bloom the following year. If I sow them in the summer, the plants will grow much faster than those sown in the spring. If I want to get a jump start, I sow them in April and then plant the young plants out in the garden. These will bloom much faster than those sown directly. For green manure or soil improvement, I sow annual lupins directly into the bed from April to August.
How to Help Lupin Seeds Germinate Better
Lupin seeds are pretty large and have a tough outer shell, which makes them harder to germinate. To give them a little help, I rub the seeds between two pieces of sandpaper to scarify them. After that, I soak them in warm water for 24 hours to help them swell before sowing them.
Sowing Lupins Directly in the Ground
I make sure to choose a sunny to partially shaded spot with crumbly soil. Lupins like to grow in clusters, but I make sure to leave about 40 to 50 centimeters of space between each plant. Lupins are light-sensitive when it comes to germination, so I press my finger or a stick into the soil to make 2-3 cm deep holes, place the large seeds in individually, and then cover the holes lightly with a rake. I keep the soil moist until the young plants are about 20 centimeters tall. Once they have established their roots deep enough, they can take care of themselves. After that, I only water if the soil surface is dry.
Sowing Lupins as Green Manure
Aside from being a beautiful ornamental plant, the lupin is also fantastic for improving soil. It’s especially good for loosening up compacted clay soils up to two meters deep – great if I’m working on a new garden. For example, the Narrow-leaved Lupin (Lupinus angustifolius) is perfect for this. I scatter the seeds broadly on loose soil, rake them in lightly, and keep the soil moist after sowing.
Sowing Lupins in Pots
If I’m looking to integrate lupins into an existing border or want quicker flowering plants, I prefer sowing or pre-growing them in pots. This way, I can place them exactly where I want them, and the young seedlings won’t be crowded by neighboring plants. I soak the seeds for 24 hours, just like with direct sowing. I fill small pots or seed trays with seed compost and press it down. Then, I sieve some fine soil over the top and water it lightly. I press two or three seeds into each pot about two centimeters deep and cover the hole.
Sowing in seed trays is also a good option if I want to grow a lot of lupins. However, I’ll need to transplant the seedlings into smaller pots once the first true leaves appear after the cotyledons.
