Hardy Tropicals UK

Hi,

I've ordered some Delosperma Cooperi in mixed colours to grow in a tub and in the ground.

I'm in the North of England (Yorkshire) but understand they are hardy provided the roots don't get too wet.

I took advice from my local garden centre and the RHS website and both seemed to suggest planting them in John Innes No:3 with added grit sand.

My local garden centre suggested a ration of 1:4 of John Innes to sand. (They originally advised horticultural grit).

I was considerer screened top soil and sand but they steered me away from this on the grounds of no fertiliser.

Anyway, what happened is I bought No:3 and Horticultral grit and mixed them 2 x 25 Litre bags of No: 3 to 1 bag of horticultural grit. The resulting mix was stony and appeared well drained. However, when I added water, I noticed it stood a lot on the surface and I felt the soil felt quite wet when I tested it some time afterwards.

So I went back to the garden centre and this time they said they meant sharp sand not grit.

So I bought sharp sand, emptied the tubs and mixed 1 bag sharp sand into the tub (2x25 litres No: + 1 Grit).

I watered the mix and again it felt wet some time afterwards.

I've since added a couple of handfuls of peat based compost into the very top layer of the tubs and this seemed to lighten it a bit, but I'm still concerned its too wet.

When watered, I don't get drainage out of the base of the pots - they're drilled and have around 1/2 inch to an inch of pea gravel in the bottom.

What am I doing wrong and can anyone recommend a good soil mix for Delosperma as I'm rather fearing I need to start again.

Welcome and congratulations on living in the greatest county of them all.... Yorkshire!

I haven't grown Delosperma but to answer your question regarding getting a very free draining mix simply add more grit and try and avoid using peat. Sand can help break up soil but grit is better for faster drainage. You could even add perlite but this looks a little artificial in the garden but excellent in pots.

I put my Delosperma Cooperi into poor ordinary soil. This is a photo of them. They spread like wildfire only beaten by Lampranthus.

Wow Impressive display Kindred.

They are one of the nicest plants if you can grow them.

Yorkshire Kris wrote:Welcome and congratulations on living in the greatest county of them all.... Yorkshire!

I haven't grown Delosperma but to answer your question regarding getting a very free draining mix simply add more grit and try and avoid using peat. Sand can help break up soil but grit is better for faster drainage. You could even add perlite but this looks a little artificial in the garden but excellent in pots.

So your approach would be maybe another bag of grit per tub?

Alsone wrote:

Yorkshire Kris wrote:Welcome and congratulations on living in the greatest county of them all.... Yorkshire!

I haven't grown Delosperma but to answer your question regarding getting a very free draining mix simply add more grit and try and avoid using peat. Sand can help break up soil but grit is better for faster drainage. You could even add perlite but this looks a little artificial in the garden but excellent in pots.

So your approach would be maybe another bag of grit per tub?

Yep.

OK thanks.

I'll get some alpine grit this time and add it to the tubs.

Mine are grown in 'ballast' with 6mm (pea) gravel and a small amount of JI.... maybe 5%.

Have to keep clipping it back or it takes over the whole arid bed.

Delosperma cooperi is the most reliable Delosperma but only comes in one colour as far as I'm aware. There are other species, hybrids and forms coming available but they aren't all winter hardy. I've grown D. Ashtonii from seed and that seems to be hardy. Another D. karooicum with white flowers doesn't survive in the open garden. D. nubigenum with yellow flowers is almost as reliable as cooperi as is basuticum. One I bought as Delosperma cooperii "Table Mountain" is actually D. John Profitt and that also seems to be hardy. A few other mesembs I've tried seem hardy:

Chasmatophyllum musculinum
Ruschia pulvinaris
Glottyphyllum species

For pot culture I use 2 parts JI no. 2 and 1 part alpine grit. In the garden I use mostly grit and larger gravel/ballast up to 20mm.

I'm in Yorkshire too by the way. Whereabouts are you Alsone?