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How big do lupins grow?

If you are thinking of growing lupins in your garden then you will want to know how much space they take up. Do you have enough room or will you need to create space? To start with you will need to know how big do lupins grow? Well, I have quite a bit of experience growing lupins so have created this handy guide to help you out.

To start with let me just say that I will be talking about perennial border lupins here not tree lupins. Perennial lupins are what you will commonly find in UK gardens with tree lupins being much rarer.

Lupins in bloom
Lupins in bloom

How big do lupins get?

Different lupin species grow to different sizes, but the most common Russel varieties can grow up to 4ft tall and 1-2ft wide. They will take a few years to reach this size and are really easy to cut back.

You can find varieties that grow smaller than this, if that is what you are after then look for dwarf varieties, this will normally be explicitly stated on the seed packet or plant label.

Lupins should be cut back to the ground every year, so the growth will start over again every year. The older your plant the stronger its root system will be and therefore it will reach a greater size. This does not go on indefinitely and most plants will be fully mature and not really grow any bigger after 2-3 years.

Lupin in mid spring
Lupin in mid-spring

The above photo is of one of my lupins growing on my allotment. The photo was taken in mid-April and this is the lupin’s second year of growth.

You can see that even in mid-spring this lupin has put on a lot of growth. As soon as the conditions are good enough these plants will burst into life and starts growing with serious gusto. The more sun a lupin gets the bigger it will grow, those grown in the shade don’t tend to grow as big as lupins grown in full sun.

How close can I plant lupins?

The general advice for planting lupins is to try and plant them 30cm apart. like most gardening advice though there is a lot of leeway on this and the decision really comes down to what type of display you are after.

Lupins are quite happy to be crowded and will grow into each other just fine so you can plant them a bit closer than the usually recommended 30cm. This is how they often grow in the wild, producing vast swathes of uninterrupted lupins. To find out more why not read my how far apart to plant lupins article.

lupins in iceland
lupins in iceland

More on Lupins

Lupins are a beautiful flower that you will find in many British gardens. Lupins are a staple of British cottage gardens, famed for both their height and colour. Originally hailing from the Mediterranean they are a perennial that will greet you with a gorgeous display year after year.

They produce a large flowering spike that is full of colour and each plant can have lots of these spikes leading to a fabulous display. They will begin to flower around may and can last well into June. The flowers do go to seed quite quickly but your lupin will continue to produce more and more new spikes.

To get the best out of these spikes though it is essential to deadhead the old spikes to give the new ones a chance to flourish. Also cutting your lupins back in autumn can help them the following spring. The seeds are edible but if not treated properly first they can be poisonous to animals and humans. Greenfly can be a common problem for lupins here in the UK.

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