Lupins are a great perennial flower and are loved by gardeners up and down the country. So loved in fact that if they start dying off you will rightly be very worried. So with that in mind let’s have a look at some of the more common reasons to explain why your lupins are dying, and more importantly, what you can do to fix it.
Reasons for dying lupins
Here are some of my top reasons why your lupins might be dying. Have a read through and be aware of what signs to look for in your lupins to ensure they are always healthy.
Lupins are susceptible to a few different pests. Slugs and snails for one absolutely love munching on lupin leaves. Slugs are very unlikely to do enough damage to cause serious harm to a well-established lupin plant though and a much more of a threat to young seedlings.
That brings us to a pest which is probably the most common cause of a fully grown lupin dying off and that is lupin aphids. Aphids can take over a plant in a very short period of time so if you arent paying attention you could end up with an infestation as bad as the one in the photo below.
Lupin aphids don’t “eat” the plant per se, but this does not mean that they are not dangerous to the plant. They suck the sap out of the plant and if there is a large enough infestation they will do enough damage to cause the lupin to droop and sometimes even die.
You want to try and take steps to control aphids as soon as you see a few on your lupin as they can take over really quickly.
How to get rid of lupin aphids
So you’ve found aphids on your lupins, how do you kill them off? I have a few ideas for you below, some organic and some not.
Probably the most common option and also the most effective. You can get organic bug sprays but they are never as good as the non-organic ones.
If you just want to kill the aphids and save your lupins then I recommend the miracle grow bug spray. I have used this spray myself after being recommended it by another gardener and it really does work wonders.
Kills all major insect pests, including whitefly, greenfly, black fly, red spider mite, caterpillars and lily beetle, scale insects and mealy bugs For use on flowers, fruit and vegetables.
There are lots of old wives’ tales when it comes to homemade aphid sprays which may be worth trying out but I must say I have not used them myself as they never seem to work.
Garlic spray, mix some crushed garlic in a spray bottle with plenty of water, spray directly onto the aphids and wait around an hour before spraying off with regular water to rinse the flowers.
Soap spray is also meant to work well on lupin aphids. Mix some washing up soap with water before applying and rinsing off as above.
Knock them off
Aphids don’t like being knocked off lupins and can struggle to get back up onto the plant. If you regularly knock them off the plant and squash a few then this can help to keep the infestation in check and is about as organic as gardening gets.
Another pest control solution like the nematodes for slugs. Ladybirds love feasting on aphids and a single ladybird can eat thousands of them in a lifetime. So if you have lots of aphids then you don’t have enough ladybirds in your garden, but how can you fix this?
These native British Adalia Bipunctata ladybird larvae have a huge appetite for soft -bodied garden pests such as aphids (greenfly and blackfly), spider mite, scale, mealy-bug etc.
These are live ladybirds in their larvae form. You can apply them directly to the plant where they will immediately get to work munching on aphids. When old enough they will transform into ladybirds and continue munching on aphids, win-win!
Most soil conditions are fine for lupins but the one thing they really don’t like is wet roots. If your soil is waterlogged then this could be the reason for a dying lupin. They are very susceptible to crown root rot and really don’t like being in boggy ground.
You have two choices if this is your issue. You can either move the lupin to another area in the garden or improve the soil drainage around the lupin.
If you choose to improve the soil try to add sand and maybe even a bit of gravel to your soil mix, this will help to improve the drainage. If the lupins are in a really wet spot then you might have to take more serious action like digging a french drain.
Virus and disease
There are lots of different diseases that can affect lupins and probably more than I could ever list. In truth, there is not a lot you can do about most of these problems and sometimes the best solution is to remove the affected plant and destroy it.
Small brown spots on the leaves or stems of your lupin are a sign of this disease. It is a spore born disease that lives in the soil and there is no real cure.
My advice is to avoid planting any lupins in this same area of the garden again for several years which should give the spores time to die off.
After a few years have passed it should be safe to plant lupins in this location again.
The leaves of a lupin will have a powdery growth on them. This is often white or a pale grey but can sometimes be black. This one is usually a simple cure as it is often caused by improper watering and not enough airflow.
Remove the affected leaves from the plant and then try to water at the base of the plant going forward and avoid watering the leaves.
As well as sucking the sap out of lupins and damaging them that way aphids can also transfer viruses to lupin plants. A lupin affected by an aphid virus will normally have strange, stunted growth which is often twisted downwards.
There really isn’t any cure so you just need to remove the plant and destroy it, don’t put it on your compost heap in case the virus spreads in your compost and affects other plants.
Seasonal Die Back
This is, without doubt, the most common reason for lupins dying off but it is likely not why you are here. If you do happen to be inexperienced with lupin growing though let me just say that it is completely normal for lupins to die back in autumn.
This is normal and part of a lupin’s yearly growth cycle. I promote cutting lupins back to the ground in late autumn, ready for them to bounce back to life the following spring.
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.