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Acanthus spinosus Failure to flower

London, United Kingdom Gb

My acanthus spinosus failed to flower last year and looks as if it will not flower this year either.

Any ideas what I'm doing wrong. It is in partial shade in a London Clay soil which has been well worked and is of good quality. The plant seems healthy enough but has grown wide rather than upwards many thanks

On plant Acanthus spinosus



This plant prefers full sun and free draining soil - given it's environment in your garden, perhaps that is why it's not flowering, though I'd think the shade would be the biggest problem, especially if the shade is created by overhanging shrubs or trees. That would also explain why its grown wide and not up

1 Jul, 2009


I have this plant growing in a mainly shady aspect and it is flowering, I only planted some small plugs last year!! My soil is a sandy, rocky type which I nourished with small bark chippings and compost and plenty of bonemeal. If it looks healthy I would be happy, but you could feed it with a solution that encourages fruit/flowers, I'm not sure whether this is potassium or nitrogen. I have also seen this plant growing in shady areas in other gardens and parks so I'm not convinced it relies on complete sun.

1 Jul, 2009


I have it in both sun and shade. The one is sun flowers more freely and at a younger age but the shady one got there in the end. So - it prefers sun but will tolerate shade

1 Jul, 2009


Oh dear - must be your clay soil then. Give it some, oh god, having a senior moment, I know exactly the name of this product, but it's completely gone for the moment. I use it on raspberry canes in the spring as a top dressing and it's a white powder, encourages flower/fruit formation - I will hunt through the shed tomorrow to find it and let you know (assuming it doesn't pop back up tonight when I'm not thinking about it!) That said, though I'm still curious as to if there's anything growing overhead - the fact that it's low and wide is intriguing.

1 Jul, 2009


Sulphate of potash is what I meant (dear oh dear, it's only taken 12 hours for the name to surface in my brain). Apply this a couple of months before its due to flower next year.

2 Jul, 2009


I'm delighted at the response from you all. Thank you. This is my first time on site. I've taken on board your comments. Had a look at it this morning and the sun was shining nicely on the plant and it didn't really look that shaded for the rest of the day. However, it is fairly crowded in amongst other plants. Maybe that's a contributory cause

Thank you Bamboo for the potash advice, ditto Andrew - it may be a little hungry though I do tend to throw a fair amount of growmore round the place at the beginning of the season.


2 Jul, 2009


Growmore is high nitrogen, and a good general feed, but for flowers, try the potash trick.

2 Jul, 2009



I'll reach for the potash. Thanks again.


4 Jul, 2009


Flowerd 2ndyr. Healthyfoliage but no flowers lastor this yr?

12 Jul, 2009


My plant is in heavy clay soil and is sheltered from the sun for a good part of the day by my garden wall but it is flowering this year!" Mind you, it came from someone elses plant in 2006 and it didn't flower until this year.

12 Jul, 2009


From the answers that you wonderful guys gals and plants - is Bamboo a plant? I think I may need to be patient.

Many thanks for all your help

13 Jul, 2009


I 'admired' a spikey plant in someones garden way back in 2004 and they got a big knife out and chopped through the root and gave me 2 spikey green leaves and a bit of root. Having nurtured it through a winter, until it got established, I put it in the garden. It got dug up as a 'weed' and trampled on [by the OH] and eaten by goodness only knows what. I had pretty much given up on it doing anything except produce these two spikey leaves that never really amounted to anything. Until this year [2009] when it has produced several dark, glossy and very spikey, leaves followed by 2 flower spikes, with their emerging flowers. Currently about 2 feet high, but in the front!!! of a bed of mature shrubs which, thankfully, slopes steeply upwards and behind it. Now I know what it is and glad we left it alone. It gets full sun and is on a clay soil, in a bed that's kept moist from all the water that runs down our drive, and off the garage roof, and into this bed - no watering needed here in the Summer for us!!!!
Lovely plant and certainly eye-catching. Cetainly wasn't expecting the flowers as the original plant was just green, spikey and architectutal.

12 Aug, 2009


Signing on for first time as was searching for this topic because of the cold weather. I have two plants, one flowers and one doesn't, and I've assumed until now that it depended on how much frost they got, as one always gets more frost and cold than the other. Let's hope I 'm, wrong as they're both going to lose their leaves this year.

10 Jan, 2010


Be interesting to see if neither flowers, Loundshay, or whether the situation remains the same - which would mean it can't be cold or frost. Can you let us know, please? and welcome, by the way

11 Jan, 2010


Very belated entry into this. Hope you are still around, Janet! Unlike some of the above members, I am far from being an expert but I have this plant (see photo & comments on my page) which is in full sun except for a few hours a day when it is shaded by a Viburnum. A fellow member’s (Stroller’s) plant suffered from mildew. Could this have been a factor? Just a thought! Welcome to GoY Loundshay.

12 Jan, 2010

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