How to grow lupins from seed – step by step
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Propagating lupins from seeds and cuttings, along with dividing them, are the three ways to make the most of your lupin production. I cover taking cuttings in the article Propagating lupins by taking cuttings. I haven’t covered dividing lupins as it’s extremely difficult to do successfully due to the plant’s long tap root.
Seeds are a great way to grow lupins from seeds you have collected, or you can purchase them from garden centres and nurseries. Read on to learn how to propagate lupins from seeds.
Collecting the seeds
Lupins are easy perennials to grow from seed. If you already have lupins, wait for the flowers to die off and leave them on the plant. They then turn into seed pods, as shown in my picture above, and the plant puts its energy into creating seeds. Break open the seed pods to collect the seeds, the seed pods should be dry and brown, and the seed will just fall out of the pods.
Two things to note:
If you leave the seed pods alone, they’ll sow the seeds by themselves (self-seed) and you’ll have more lupins in your current lupin patch. You can always wait until the seedlings have grown into strong small plants and transplant them elsewhere in your garden. This can be a little difficult as they don’t always transplant well, which is why I like to sow the seed in individual seeds, so I don’t have to disturb the roots.
Lupins grown from seeds can manifest in a variety of different colours (often violet), not necessarily the colour(s) of the parent plant. Just something to keep in mind, if you want to same colour and variety of teh parent plant, you will need to take cuttings.
Preparing the seeds
The seed coat of lupin seeds is tough and you need to weaken it to give the seeds the best chance of germinating and propagating lupins. This is important if you sow them into individual pots as it saves waiting compost with a bad germination rate.
Here are three ways to do this:
- Use a sterilised knife to make a nick in the seed coating through which the seed can grow.
- Lightly rub the outer surface of the seed with sandpaper to weaken it.
- Soak the seeds in warm water for 12 to 24 hours just before planting. (This is what I do and sometimes I nick the seed with a knife first)
This step is optional but is known to increase the germination of the lupin seeds as they think they have already been through winter.
Place the seeds inside damp paper towels and put them inside a sealable plastic bag. Leave the bag in your fridge for a week to give the seeds the cold treatment.
Planting the lupin seeds
You can sow the lupin seeds directly into the ground. There’s no need to propagate lupins in pots first unless you want to grow them on and plant them in the final position later. Keep them moist, and the seedlings should appear within three weeks or so. I have had them germinate in 12-15 days in a propagator.
Choose average soil and sow the seeds about 0.5cm under loose topsoil. If growing them in pots and seed trays with cells, use seed compost. My article How to grow Lupins describes all the best growing conditions for your lupins.
When to plant
If you’ve treated your lupin seeds (soaked them, weakened the covering, maybe chilled them) then you can plant them in the spring and summer. You have until the start of August to plant them, giving them time to become established before the cold sets in.
Another option is to not treat the seeds at all and to plant them directly in the ground between September and November. The winter cold chills the seeds for you, and they’ll germinate in the next spring.
Your new lupins may bloom in the next growing season to the one you planted the seeds in. However, don’t be surprised if the plant grows but blooms don’t appear. They may need another year to become established strongly enough for the plant to expend its energy on producing flowers.
I like to grow my lupins in pots or trays with individual cells, so I don’t have to disturb the root system when transplanting them. I then keep them in a cold greenhouse before planting out in spring, usually around the end of April. I usually bring them out for a few hours a day for a week or two to harden them off first.
All parts of the lupin can be poisonous to people and to animals. Be sure to wear gloves when working with them.