[barbarella]

I sowed some house leek seeds (from Mr Fothergills) on 4 April very thinly in John Innes seed compost and a little sand, and they germinated well.  A lot of them are separate but a few are in clumps of two or three.  I am wondering at what stage to pot them on and what sort of growing medium.  I imagine I should use lots of sand or grit, but whether to use peat or loam based compost?  Also what size pot, as they are still tiny, and whether it should be plastic or terracotta.  Any advice would be much appreciated. 

[Trillium]

They can be separated when you feel there's enough there to work with, so probably in a few more weeks. Either type of pot is fine. Fill should be more peat based with lots of grit and sand, about 1/3 of each is good. They prefer a slightly acid soil. The enemy of sempervivums is waterlogging. I wouldn't use large pots to start with unless you're making a sort of group planting. Final planting could be a hypertufa planter. (google for how-to)

When you first transplant them, keep them barely moist for a few weeks until roots settle, then stop watering. After that, make sure pots can drain fast so sitting them on something like raised mesh is ideal. At planting time, I often mound my area up so that there's good runoff from rain, then 'mulch' with pea gravel to avoid splashups.

I guess you're aware that once the plant flowers, it dies, but there should be youngsters to take its place.

[arugula]

Tried these last year, as we have a perfect wall where you could poke them into gaps as but one place. Nil germination! Perhaps the seeds though, so maybe next year.....

[barbarella]

Brilliant advice Trillium - I am going to print it off and put it in my gardening diary to use as a guide when the time comes.  I hope I don't kill them off before then, as I am always nervous of letting the seed trays dry out, but don't want to overwater either.  The pot feels rather light so I guess it is dry so maybe I will stand the tray in water for a minute or so and then drain well.

Better luck next time Argyllie - I mixed the very fine seed with a little silver sand and sowed on the surface of the compost.  Then used a heated propagator tray on my north facing kitchen window sill where I raise most of my seeds and they germinated very quickly, much to my surprise as I am often unlucky with very fine seeds.

[sion01]

What trillium doesn't know about germinating isn't worth knowing anyway

[barbarella]

Final planting could be a hypertufa planter. (google for how-to)

We just made a hypertufa trough using these instructions which we googled:  http://www.finegardening.com/how-to/articles/make-hypertufa-trough.aspx .  I also saw someone making them at the Chelsea Flower Show (on TV) last week and they used equal proportions by volume of portland cement, peat free compost and kiln dried sand in a polystyrene fishmonger's box.  Our fishmonger says his fish comes in plastic boxes now, but we were lucky enough to find suitable mould from packaging. 

Anyway, we used two parts cement to three parts potting compost and three of perlite as per the googled instructions and have just turned it out of its mould - it looks great!  Now we've got to wait another few weeks for the trough to cure properly and the lime to leach out - hope the sempervivums can wait that long as they are bursting to come out of the seed tray!

[Trillium]

Truly hope you remembered to put several drainage holes in the bottom 

I have hypertufas and some leaf-printed patio slabs on my summer agenda for this year. My hypertufa mix will be mostly peat, portland and perlite. I'm the one who has to lug them about so I don't want them heavy. I'm also making little raised foot knobs for them to sit on, otherwise the sow bugs gather like crazy.

You can also cast them on top of sand mounds sitting on plastic, then cover them with plastic for the required time. I cast a concrete birdbath this way and it worked perfectly. I set down hosta leaves first for a decorative edge on the birdbath. Once it's all dried (about 2 weeks) the hosta leaves easily peeled off or scrubbed off with a nylon scrubber.
You can also use round plastic buckets to shape interiors, but first line the outside of the buckets with cling film so it doesn't stick to the mix. A larger bucket, lined inside with clingfilm, can be the exterior shape.

[barbarella]

Thank you Trillium for some great ideas.  I love the idea of the hosta leaves.  I'm not sure what you mean about sand mounds.  Do you mean you make a heap of sand and cover it with clingfilm, then use it as a mould?  How do you stop the sand collapsing?  I am really interested in this, so hope you don't mind me asking.

[Trillium]

Don't mind at all. Yes, you mound some quite damp (not soupy) sand into the shape you want on a sheet of poly.  You then stretch some clingfilm over the sand so it's past the area you plan to apply the mixture. Apply the hosta leaves (no stems, good side down) if you want and remember that everything is in reverse - whatever dips down in the sand cast will stick out in the final product, etc. The dampened sand will pretty much stay in place once wetted and shaped. Just don't go pounding it, etc. Drainage holes should be made once the shape is made and while the mix is damp. I use sticks with clingfilm attached, then pull them out once the mix starts drying a bit and won't 'fill in' the holes.

Do this in a shady area and where there's no traffic to disturb the unit while setting. Slow drying is superior to fast (sun) drying. If doing the concrete, let it set for about 2 weeks before touching and ensure it's covered with poly. When your unit is set, you can reshape the sand for the next project, or use it for something else.

I don't think the hosta leaves will work with hypertufa but you can always try. It definitely works for concrete cast. Here are some more ideas. Just click on the pic.
http://www.littleandlewis.com/garden.html

[barbarella]

Thank you for your very useful reply Trillium.  I think I can feel a new hobby coming on!  I love the Little and Lewis website.  Their paintings remind me of Frida Kahlo's.  And I'd love to visit their garden.  I have been fascinated with the Puget Sound since I read Betty MacDonald's book about Vashon Island, Onions in the Stew.  Can you get to Bainbridge Island from Seattle?

[Trillium]

Yes, you can ferry right from Seattle to Bainbridge Island. Or, you can drive around to it. The island is large so you'll need a car to get around.

http://gonw.about.com/od/washingtongetaways/ss/bainbridge_7.htm

[barbarella]

Thanks Trillium - now I can feel a road trip coming on as well