It's hard for me to ascertain without a photo so now I can only go by what you say. I don't know what is going on with your lupins but they are bi-annual plants - maybe a strong one with give you three years. These grow natively up in Canada so they like cold weather. They usually bloom the 2nd year.

I have posted a blog for you on root systems of lupins, which were sewn in early May, hope this helps.

Thanks for the responses and the blog.

The roots on the failed seedlings were very poorly developed. I am not sure if this would be normal for young seedlings. Maybe a single, short thread like root - 2/3 at most. When I examined them, I was not surprised that they had failed to develop as the top growth was significantly better than the root development.

As I am in Scotland and have grown lupins many times from pot plants, I know that they are happy in this climate. At least they are outdoors. So, I am puzzled as to why they keep failing.

Interesting. I have grown some Lupin seed this year from a neighbours garden and had good germination, like you did and like yours they have gradually failed. Oddest thing is that in a previous garden I never had to collect the seeds as there was always a good number of good sized seedlings round the parent plant which I could dig up.
Wondered if it was some problem with the compost, but other things have grown well in it.
Also for supposedly biennial plants, the ones in our neighbours garden were given to them when they moved in 10 years ago.
The ones in our previous garden survived for many years only succumbing in the end to Lupin aphids.

Thanks, Owdboggy. Interesting that you had the same issue.

I have grown lupins from plants many times and they have lasted longer than 2 years. In fact, some seemed to succumb to a severe winter a few years years back otherwise, I have a feeling that they would have continued. Several other plants were lost that year.

I have also a lovely yellow one just now that is at least 5 years old.

I actually thought of them as perennials until recently.

Band of nobles are a good perennial lupin, I have some that are 10 yrs old. is there anything left in the compost? I'd expect late ones to die back now anyway as they don't keep leaves all winter. The growing part or 'crown' could well be below soil level and will grow away again in the spring. I usually start mine off in Feb/March. put the pots outside with some shelter but not in a rain shadow and you may find you get new ones next year.

but they usually have a very strong root almost like a tap root in my experience.

There are many types of lupins from annual to perennial as well as shrubby/woody ones.

If it were me I'd set more seed off in the spring.

There are 2 seedlings left in the compost. Neither doing well, but I will keep going with them until they die too.

I have decided to do what you are suggesting. It is too late to start any now this year so it will need to wait until spring, but I am worried that the same cycle will simply be the case then also.

I've always direct sow my lupins - it never fails. They have a large tap root so transplanting them could be dicey. Also don't keep them too wet - just slightly damp and they need lots of sun and good air. Also don't fertilize your lupins. It will burn the roots. Here is this...

'Easy to grow, lupine thrives in cool, moist locations. It prefers full sun to light shade and average soils, but will tolerate sandy, dry soil. Plants develop long taproots, so loosen the soil to a depth of 12-20 inches using a rototiller or garden fork. They will not grow in clay.
Sunlight: Full sun to light shade
Maturity: Days to bloom varies depending on fall ...
Spacing: 12 inches'

https://www.planetnatural.com/growing-lupine/

Thanks Bathgate. I do wonder about the moisture in the soil. Although the compost is not too wet and I have mixed a lot of sand and grit in this batch, seedlings do seem to perish after watering. I only water when the surface of the compost appears to be drying, but still wonder if the roots are too weak to cope with this.

is the sand builders sand? If you do use builders sand it might be worth washing it first to remove any salt that might be present.
I always start mine off in pots 9cm wide and tend to use a soil based compost [John Innes No 1] when they get 4 true leaves and if the root is down to the bottom of the pot I then transplant them into a bigger pot.

When do you move your seedlings on to the next pot? I wonder if you are doing it too soon. Also they wont need covering, that will encourage damping off which is a fungal infection.

try watering from the bottom. put the pots on a tray and add water to the tray.

To be honest, I cannot remember where the sand came from. I have had t in my garage for many years. It is very likely though that it would be builders' sand as I certainly have not bought sand from a garden centre.

This set of seedlings have not been moved on to another pot. They are still in a 4/5" pot where they were sown. The first set were sown in a tray and moved into a separate cell tray when they started to show their first pair of true leaves. The roots on these were very fine and sparse.

Forgot to mention. The first set of seeds sown in the tray were sown into ordinary seed compost - Miracle-Gro I think - without adding any sand or grit. I am not a fan of the new type of compost as it appears to me that it contains a lot of composted paper type material. This is why I added sand and grit.

Added some pics and from these you can see the corpse of the dead seedling. It also looks like the other larger seedling is going the same way too.

they look to be 'damping off' that is a fungal disease. Too moist & warm. Avoid composts with added 'feed' such as miracle grow. good air circulation and cooler conditions. Band of nobles strain will grow in an unheated greenhouse from about Feb/March.

I think it is a case of killing with kindness.

Thanks, Seaburngirl. I'll try that next February and hopefully have better luck.

I posted this question last year, wondering what the problem was with my seedlings. This is just an update.

This year, I sowed more of the same seeds into compost containing no sand or grit. I also sowed some new seeds obtained from eBay. The original seeds that failed were produced by Thomson and Morgan....... the eBay ones came in an unmarked plastic bag.

I have posted a pic above of their progress. The seedlings to the left are those bought on eBay. The ones n the right from T&M. The T&M seeds have failed again as can be seen and the eBay ones are fine. The T&M seeds are Band of Nobles mixed - the eBay ones appear to be the same but are simply described as 'mixed'.

That's interesting. I've never seen an entire packet of seeds all fail at once. Do the seeds need to be stratified before sowing? Some seeds need a certain number of cold days (winter) to wake them up. Some suppliers will stratify the seeds before selling, others don't and you'll have to do. You can try placing the TM seeds in the refrigerator in a plastic baggie for a couple months - then try to grow them.

No there was no recommendation to do that. I knew some mecenopsis seeds needed stratifying, but never thought about lupins.

I have pricked out some of the eBay seeds this morning and it will be interesting to see how they develop.

MY first thought was damping off. You can avoid this by treating the soil of the seed tray with Cheshunt Compound before sowing. Not sure you can still buy this in GB but you can get the two consituents on ebay and mix them yourself. Always worked for me.

Thanks, Yorkglass. I still seem to have the problem once the seedlings are pricked out. I have a tray of them that I am leaving a little longer as the first batch mostly collapsed after pricking out.

don't prick them out until they have at least 2 preferrably 4 true leaves. that way the roots are more likely to respond positively.

I dont tend to have much success with T&M seeds but no problems with others.
usually lupins don't need cold stratification.