Lupins: An Experts Ultimate Guide

September, 2021
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Lupins are perennial plants that produce their first flowers in late May or early June. They can continue flowering into the beginning of August if they're regularly dead-headed. The flowers are large and display almost every colour a flower can, including shades that are usually not seen.

When grown from seed, lupins are an excellent plant for growing in a cottage garden. This article will only cover perennial varieties of the lupins since annual plants have different needs.

Thinking about adding Lupins to your garden? Check out our useful checklist below:

  • They prefer soils with a pH value between 6.0 and 7.5, but they will grow successfully in the majority of other soil types, even those that are low in nutrients.
  • One way to include them in your garden is by planting five or more of them as a group. Alternatively, you could mix them with other bedding plants in an interspersed fashion.
  • They like well-drained soil, but can be successful in most gardens
  • They don't like to stand in wet conditions all the time which will eventually rot the roots (crown).
  • Aphids have been a major issue for Giant Lupin.
  • Full sun is preferred although they can grow successfully in light shade.
  • They can grow up to 1.2 meters (4ft) in height, depending on the soil and weather conditions. They don't need staking when outdoors but may benefit from staking indoors.
  • Slug and snails will eat young plants, inset especially.
  • They can withstand frost and cold extremely well.
  • They are healthy plants and you do not have any great knowledge needed to grow them.

Lupin Growth Calendar: When To Sow?

Sow Lupin seeds indoors - March week 1

Buy and pot up plug plants - April week 3

Harden off Lupin plants - April week 4

Plant out Lupin seedlings - May week 1

Harvest Lupin seeds - July / August

To Grow Lupins From Plants Or Seeds?

Growing lupins can be achieved in both two ways, either through sowing your seeds or transplanting cuttings. Costs and preferred colour decide between the two methods. Lupin seeds are about £2.50 for a pack of 40 and will give you good plants, some flowers in the first year, others might only flower in the second year.

Planting cuttings of lupins will result in independent plants that are an exact replica of the original parent plant. There are two basic types of plants: plug and pot plants. While both require more investment than simply purchasing some seedlings, it is generally a good idea to buy your plants this way because you can be sure that the plant you receive will have the variety and colour selection that you desire.

How To Sow Lupin Seeds?

The process for seeding saved seeds or seeds from packets bought in a garden centre is usually the same. For reliable results, sow seeds indoors; they can also be planted outside a month later if desired. The best time to sow lupin seeds indoors is around the first week of March.

In order to avoid having longer wait times between when you sow the seeds and when they start growing, soak them before initial sowing. You can sow seed initially in seed modules, and then transplant into a larger container when the seedlings have four or more leaves. To plant straight to pot, start with a seed and layer it about 1 cm deep in an 8 cm/3-inch container of the best quality compost you can find. After sowing cover the top of the container with compost. Water lightly and keep it moist but not wet which could "lodge" the root ball too deeply into this delicate material

Lupin seeds will germinate best in a range of roughly 15°C to 20°C or the temperature of a cool room in a centrally heated house. Seedlings will usually emerge after 10 to 15 days. Advise keeping them in a cool, light position like on a windowsill but not one with any direct sunlight.

In order to be able to plant your plants outside, harden them off about a week or two prior.

Where To Buy Lupin Plants?

These plants are popular and can be purchased from garden centres or on the internet. Suppliers typically offer large pots as well as smaller ones for purchase.

How & Where To Plant Lupins In Your Garden

Lupins prefer a sunny location but will also grow well in partial shade; they do not grow well in deep shade. Plants of this variety do well in a wide range of soil types

However, if your ground is predominantly chalky or waterlogged, these plants are more likely to die during the winter. Ensuring that there is enough soil with chunks of grit before planting will be key for success.

Planting lupins is simple. Dig the garden area well where they are to be planted and sprinkle blood, fish and bone into the soil. Dig a hole for each plant and carefully plant it in so it reaches the same height as how tall it was in the pot. Lupins grow from crowns and if these are planted too deep they may rot. They should be planted at least 30cm to 45cm (12in to 18in) apart.

How To Look After Lupins?

Removing or deadheading flowers

To reap the longest flowering period possible from your lupins, make sure to cut off heads when they have shrivelled up. The flowers will die from the base of the flower head. Deadheading is recommended after two thirds of the flowers have died, new smaller flowers will soon appear.

How to care for lupins over winter?

There are no actions to take as the foliage turns brown and starts dying back during winter. In early spring, use scissors to trim dead leaves. There are many factors that determine how long a lupin will live, including the conditions in which it is grown. Generally speaking, they will produce flowers for five years and then become woody and unproductive. At this stage, you may want to dig up the bulbs and divide them. You will break their long taproot and they may not grow for four or five years. But if you do this, the plants will produce flowers for another four or five years.

How much water do lupins need?

Lupins are strong, long-lasting perennial plants that do not need frequent watering to survive. They make for great plants because they can take care of themselves in terms of water and nutrients as they have wide taproots that allow the roots to find water even during periods of extreme drought. So you don't need to be alarmed if your lupin is wilting from lack of water.

Do lupins need a feed?

Lupins can grow without the need for fertilizer, but if you suspect that there might be an excessive amount of nitrogen in your soil, it's important to know that lupin foliage will actually make them more palatable for aphids.

Diseases & Pests Lupins Are Susceptible to

Aphids

This aphid, which often attacks lupins, can cause a host of problems for gardeners. For example, if left to their own devices the Giant Lupin Aphid will result in poor flowers and foliage that are vulnerable to other pests and fungus. STo prevent aphids, spray any lupins that you have with a systemic insecticide on the first signs of invintation, which is usually May. Re-spray two weeks later. Organic solutions will not work to prevent aphid attacks as they are ineffective in this situation.

Crown Rot

Occasionally the base of plants rots and this can happen because the soil was too moist. Dig up the rotted plants, spaced out those left standing a little more, it may be that next year there is not an issue at all.

Slugs & Snails

Slug and snail problems are rampant in some areas of the UK. Organic slug pellets do not work for snails on lupin plants. Normal slug pellets seem to be effective!

Colour Changes With Lupins

Lupins will maintain their colours throughout the year. One can predict a change in colour by noticing that this plant has self-seeded (lupins are particularly good at this). Lupin plants that have successfully seeded will most likely return to their original blue hue each year, as it is considered dominant present within its genes. To prevent the plants from self-seeding, remove all of the flowers before they fall to the ground.

How to save lupin seeds

To harvest seeds in late July, allow seed pods to turn brown and then remove them from the plant. Open up the pods to get at the seeds. The seeds will keep for three years or more if stored correctly. The older the seeds, the more important it is to soak the seeds before sowing.

How to grow Lupins in containers?

One of the key problems with growing lupins in containers is they grow taller than 150cm / 60in

Only large and heavy pots are suitable for this type of plant. The need for deeply rooted plants combined with their immobile size means that potting them can't be done without moving large, heavy pots.

Planting a pot requires a suitable container (with a drainage hole in the bottom) containing multi-purpose soil and sharp grit. Apart from this, it should have no special requirements.

To make these plants thrive, they will need watering often. Rainwater is best for them because they prefer slightly acidic conditions. To collect rainwater conveniently see our article on water butts that can be used in the garden or patio. A fortnightly application of liquid tomato feed from April to late June is the best way.

When the leaves die back in winter, you should only remove them if it is to give your appearance a clean look. The best time to do this is in spring when new shoots are showing.

Lupins are beautiful flowers with long taproots that help them survive even in the harshest of conditions. They need very little care to stay healthy and grow, but they do require water at least twice a week or else their leaves will start wilting. If you have any questions about lupin plants, feel free to ask our team for more information! We're happy to answer your gardening question by emailing or leaving a comment below.

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