Cutting back Lupins to encourage "second flush"

Hi. If cutting back lupins to ground level, do you still need to ensure you cut to a bud, or will the flowering stem re-grow naturally? If so, how? Or does the new stem simply emanate from the crown in place of the one you have cut back?

Thanks.

 

After the first flush of flowers, I cut my lupins back to a low side stalk, not right to the ground. I get some secondary flowers but they're never as good as the first ones.

I only cut back to the ground when the whole plant has died down.

 

I don't know the specific answer because I only grow Lupins as a biennial (tip picked up from Christopher LLoyd's books). After they have flowered I dig them up and throw them away and replace with a late flowering plant, such as Dahlia, Cosmos, Cleome, Salvia etc.

However, I think that the principle must be that you cut off as little as possible - just the old flowering stalks. Anything else that you cut off has to regrow and this takes time, and any healthy leaves that you leave on help to provide the energy for the regrowth.

Some things like Centranthus (Red Valerian) I will cut back by a third or so, but this is only because there are so many small flower heads that you can't deadhead them individually. Also it is a very strong grower and is often back in flower within three weeks.

 

Oh gardening is wonderful. I love lupins and this year sow them rather early. Flowered in the middle of the summer. As cutting back I recommend to cut back only the dead flower. Then to ground level in the autumn.
One of my established one was literally flowering the whole season long! Is this normal with lupins or I just got very lucky??

 

I'd love to grow lupins, but can anyone tell me why they always die? :(

 

in what stage?

 

I think that with Lupins and with many other plants, they have good years and bad years. Last year, when it was so wet, my Lupins were magnificant. This year they were just ordinary. In both cases they were new plants.

Fidgetsmum - I can't remember exactly, but I have a feeling that Christopher Lloyd commented that Lupins had a habit of dying without warning. Which was one of the reasons he grew them as biennials. There are quite a few plants that are described as biennial or short lived perennial - such as Lychnis coronaris and Salvia sclarea etc, and Lupins may be one of these. Christopher Lloyd said it was only late in his life that he realised that biennial plants could be made more perennial if you removed the flowers after flowering so that they couldn't produce seed.

There are a lot of plants that are monocarpic - ie flower and produce seed once only and then die. Producing seed is the whole purpose of plants, so monocarpicism is perfectly normal and natural. They may take one, two or 20 or more years. For instance annuals flower and die within one year. Biennials take two years. but you can also have monocarpic perennials. Some Echiums can take 3 or 4 years, and Agave americana can take from 30 to 60 years - but they still only flower once and then die.

So apart from just being a ramble - there is a moral in all this. If you remove the flowers before they can produce seed you may extend the life of some plants.

 

I've tried growing them from seed, got nice healthy plants and then planted them out but once in the ground they just die, (even when I've planted them out a week or so apart). I've tried them in different places - in sun, partial shade, shade, fed them, not fed them but still they die - I've even tried putting a solid plastic 'fence' around them to stop being eaten but it's not creatures which are to blame, they just don't seem to like my soil. In the end I bought some plants this year but within a few days they too died - apart from a couple of spindly little leaves which, after giving false hope, took just over a fortnight to die off.

 

Figitsmum - thats very strange. I was having a little google and found that Lupins like a slightly acid soil and hate lime. They will also rot quickly if manure is in contact with the crown. They also like good drainage.

They hate being moved as they have a tap root. But planting them out from pots shouldn't do any harm. Why not just grow them in BIG pots. I have loads of big plants growing in pots. I think you can do that with virtually anything. I have plastic pots up to 50 litres with two handles for carrying.

 

Thanks Peter, I'll give that a go - nothing to lose. We've got just about everything they're supposed to like, well-drained soil with a pH which ranges from 6 to netural - what's really frustrating is that a few years back, there was a whole swathe of them growing 'wild' on the Swanley by-pass in Kent and I can't get even one to flower!

 

Hi Fidget'smum,

I have a similar issue with them-I have always just written it off as me being clumsy when planting them out so I got my daughter to do them this year and they have thrived-even though she was 6 at the time she obviously as "magic fingers". I think I may be planting mine too deeply and perhaps damaging the roots or something during the process as she just stuck her hand in, moved aside a bit of dirt, plonked hers in and brushed the soil back over.

Other than the magic fingers excuse she is more gentle than I am.

 

Ah! So that's the answer. Trouble is, there's never a 6 year old around when I need one :hehe:

 

Possibly the slugs get them. The little blighters are attracted to slugs like flies to ***

 

Thanks for all the many posts to this question, I appreciate it. But I am sadly none the wiser as to whether one has to cut back to a bud or just remove the whole stem. If the latter, where and how does the new flowering stem emerge? Thanks.

 

Just cut off the flower stem, back to where the leaves start. Don't worry about buds. Its the action of preventing it from making seed that makes the plant have another go.

The mechanism behind this, is that when a plant starts to make seed, the seed bearing part (ie the ovaries) sends a chemical back down the plant, and the chemical tells the plant to stop flowering. If you cut off the seed bearing part, you have removed the site sending out the chemical. If you cut off anything more than just the ovaries, it will be purely for aesthetic reasons. You cut it back to a leaf purely to avoid having a dead stem with no leaves.

New leaf and flower buds will arise spontaneously from the acute angle that leaves make with the stem. There are loads of these points, so potentially loads of flower buds. The only reason they are not growing is that the main stem is sending other chemicals back telling them not too. Remove the main stem and the new leaves and flower buds will start to grow.