Reading about semps, many websites tout the fact that they will grow anywhere in almost little to no soil, so my question is, is there an ideal soil depth for semps? Does it depend on fully grown rosette size? My first rustic comtainer only has 3.5 inches of soil, is that enough or will semps in it not reach their full potential?
On my overgrown gravel bank, the old variety of tectorums have some rosettes 6 to 7 inches across and have formed dense colonies and they are in a poor gravely clay dirt(albeitwell draining because of the gravel and slope) thats only 4 inches deep until u hit hardpan clay and they seem to be doing just fine considering the neglect and lack of care they had for a few years at least.

I'm not sure if there is an ideal soil depth. Sempervivum can grow pretty impressive roots to anchor themselves into the rocks in the mountains where they grow naturally, but they can also grow in barely any soil at all. I always start out with small pots for small rosettes and then move on up as the plant gets bigger. If a plant has the room for roots to grow, it usually will and the plant itself will be able to grow more as well.

I grow my Semps in containers, and I prefer to use shallow and wide containers, rather than deep ones. I leave these plants outdoors year round and during our rainy period which is also winter, it needs to drain out faster. So shallow containers works much better for it. Too deep and it takes far longer to dry out. It is different when planted in ground, the roots can go far and wide.

What Paul said... If you give them more root space they'll grow larger rosettes, but each plant has specific size expectations so you won't get a 6 inch med sized semp from a smaller cultivar even if you give it a larger pot. There is some variance but only by a few inches. I do think you're more likely to get offsets if you plant with more root space but if your plants are producing offsets than they're happy!

gg5 said:I do think you're more likely to get offsets if you plant with more root space but if your plants are producing offsets than they're happy!

Well all containers, including my shallow rustic one must have very happy semps, 80 percent are throwing offsets already, and the oldest planting is only a month old. It could be the soil mix, I tried to use common sense in my mix, they are alpine plants that grow in rocky ledges and crags in the wild, so I tried to imitate that with my soil mix, half pea gravel and half very well rotted log.

Thanks for the advice everyone, so my take is on it is if i want to grow the larger varieties of semps and get huge rosettes, I wanna go a little deeper on my containers, but for medium and smaller varieties my 3-4 inch deep rustic containers are just fine.

Sounds about right yes!

Oh and... Something else to consider, heuffelliis have a larger tap root which probably need a larger pot. In case you begin growing them.

At the moment Im going to stick to semps in my containers until next years bank reclamation project, although seeing valleylynn's concrete block raised beds is giving me ideas

Oh boy, I can't wait to see what you come up with BT.

Lynn, what size are the squares on your cement blocks?
How does one know which semps are small medium and large?
When figuring root zone depth, are semps planted touching the growing medium with the rosette or can the rosette stick up in the air some? All those I have purchased this spring have up to an inch of stem bare before soil. Standard ? or sloppy grower practice? I see the advantage of starting with babies and bare root.

Good morning Judy.

There are a few reasons the rosette can have a bare stem. The main one is the older bottom leaves have died and they either fall off or are removed. This normal and does not hurt the plant since new leaves grow from the center of the rosette.
When planting I would plant the roots and a small part of the stalk leaving the rosette sitting a bit high. Then fill in under the rosette with chicken grit or small gravel of some type.
I hope this is helpful.

Judy her blocks are the standard size, I think they have 4 inch square holes on each side on each block...

I'm sorry Judy, I forgot to answer your question.
This is the size of the cement blocks I use. 16-in x 8-in x 8-in
I love them.

Bigtrout, Lynn's blocks are how I first thought to plant my newbee semps!
I have blocks but no rocks!
However, I will have to shift my area to one out of any direct sun due to intensity of direct summer sun here. Where the blocks are now they sit on part of an asphalt paved driveway, so good drainage and enough root depth area. But, the semps I have rounded up locally are already too big for a 4x4 container???

Lynn, thanks for your input on rosette/stem planting. Very helpful.
Little did I know that I would be getting so upclose and personal with these Hens and their chicks! They seem to be good plants for those who like to fuss or totally ignor!

Up close and personal is so much fun with semps.
The learning never ends.
Can you move the cement blocks to a shady area and make a small bed with them. That way you can plant the larger semps on the interior bed portion, and small type semps in the block holes.

And now these semps have me on a vigorous weight bearing exercise program what with blocks and shuffling containers filled with gritty mix. I see it all now, I'm slowly becoming one of those live forever types!

Just what kinds of roofs did these house leeks live on and what kind of 'soil depth' did they have up there if any?

So far I am enjoying them about table height for a good view of rosette symmetry.

MariposaMaid said:Lynn, what size are the squares on your cement blocks?
All those I have purchased this spring have up to an inch of stem bare before soil. Standard ? or sloppy grower practice? I see the advantage of starting with babies and bare root.

As a grower, I would never sell semps with the stem sticking out of the ground. It can indicate that they got way too wet in the winter and many leaves rotted and they pulled them off or the plant has been in the pot way too long, is probably pot bound and has a good chance of going straight to flower.
Lynn's advice is excellent as is Greg's so no need to repeat it.

Judy semps on roofs were usually on thatch which is usually 12 to 15 inches deep, sometimes deeper if they put a new layer of thatch on top of an old layer.Thatching straw was wheat or rye straw grown for the purpose of thatching so it was very long ...3' or more. It was also very straight, strong and water repellant. Not much of that grown today Some varieties of thatching wheat have disappeared completely.

Thanks for the history Ricos!
I know these plants were seen as protection from lightening so they have a mystical value

Judy, love your photo of the creative fish. It truly is amazing what he does.

@valleylynn The idea I got involves a bigger but maybe better project, I may just clear the small bank, repair the retaining wall and let the semps there spread without competition from weeds and grass, theres 3 different large old tectorum colonies and 2 cobweb noid colonies that look like they would spread to fill it all given the chance. Id hate to tear that out to only plant them again, there are a few hundred!
Just a little bank clearing has allowed these to start spreading, looks like it spreads by the day.



Clearing the worst of the weeds has made the tectorum start offsetting all along the outer edge of the colonies. Theres alot more tedious weeding to get done, its a.little tough to do without stepping on semps!



I have a bigger bank that faces south, is tree shaded in summer til around 11am and then sunnny til dusk, and full sun all winter long, and its not huge, maybe 10 feet in height but about 40 feet long, and steep enoough a royal pain to mow...its just crappy fill dirt, very gravelly so the lawn that grows there is mostly weeds, but it is already very well draining so id have a great base underneath. Your block planters gave me this idea...building maybe one at a time, step and terrace the block into the bank in a section about the same size as yours, only terraced, and between sections use block for steps the same way...slowly cover the bank in 4x8 plantings with steps between to match the terracing.
Since im terracing, instead of using the block holes on the outer edges for semps, use them for sedum to "pour" out and down over, and use the inner large sections for semps. One section at a time id slowly make my mowing easier and the bank alot prettier!