I decided finally the other week that I wanted to use the greenhouse more for my alpine and bulbs. I have lots of pots of bulbs and they are currently stored under the staging in the greenhouse with the aim of them drying out over the summer. However, I have read that plunging the pots in sand is very beneficial. It is particularly good for plants that don’t like their roots too wet.
The new staging arrived the other day sooner than I expected which meant a chaotic couple of hours which the staging was assembled and plants moved around. I hadn’t really thought about such simple things as how you fill the plunges but strangely it turned out to be more involved than I had thought.
If you just tip the sand into the plunge it really doesn’t work and you don’t get the neat appearance you see in alpine houses. It turns out you have to fill the plunge with a few inches of sand and then compact it with something like a brick. Then you carry on doing this layer by layer until the plunge is full. This makes the sand bind together and means that when you cut the holes out for the pots the sand doesn’t collapse. Having typed this it does sound a little OCD but it does work and it is strangely satisfying!
I have struggled to find information about setting up a plunge bed; no doubt the audience is a little limited. However, I came across a wonderful resource on the Alpine Garden Society website – The Wisley Diary. This was written from 2007 – 2012 by Paul Cumbleton the head of the Alpine section at Wisley. Of course reading such articles is like signing up to the council of perfection but I suppose it’s a starting point. Paul advocated laying out your pots in advance so they aren’t crowded and it looks neat. Anyway, it was quite entertaining a bit like making sand castles but in reverse.
Of course having filled the plunge with my alpines I realised that part of the plan was to accommodate the pots of bulbs! So these are still in the trays under the staging but the plan is now to move them into the plunge as they are coming into flower.
I have no idea if I am doing things right but it seems to me that the only way to learn is to have a go and see what happens. Seeing the plunge full of alpines makes me smile and I have a suspicion that this is the beginning of a slippery slope. The only obstacle is space for more frames, although there is a plan fermenting in my mind.