when growing on alpines in small pots when do they normally scorch??

[newstart]

1)Do some alpines scorch in a full light greenhouse and not others?
2)Do alpines only scorch if under watered or if watered onto leaves in the heat of the day or will they scorch if in full light pursay in early stages?
2)Do all alpines need shading in summer in early stages?
3)When are they then ready for the plunge bed. Is this after the secondary growth is put on so that full light retains the rich alpine foliage colour?

I can sort of figure this out but am new to alpine growing and could do with some advice. Most alpines are just the common ones and not the specialised alpine house types. I find that the more an alpine is shaded the less the foliage colour stays 'true' in early stages. Eg a sedum 'voodo' -darker red in colour if shaded in early stages loses its true colour. Is it for example in this case that its best to have very slight shading and as soon as its able to put outside in plunge bed to retain its good colour. Are green tinted shading better than coolglass white. I hear 'Varishade' is a clever option in that when it is dry it turns white and when wet turns transparent. Would varishade become in between transparent and white in mild conditions(ie not raining)

Thanks all!

[David Nicholson]

David, if there were a prize for originating the longest thread title I think you would walk away with it.

Can I first recommend to you a series of books that I find very useful indeed. The series is called 'The Rock Gardener's Library' and consists of around 6 books. They were published in the early 1990s and each one in the series is a gem for any beginner in what is not an easy art(or should it be science!). The series was published by Christopher Helm/Batsford and Timber Press. I would particularly recommend three of them:-

The Alpine House by Robert Rolf.
A Guide to Rock Gardening by Richard Bird
Alpines in the Open Garden by Jack Elliott.

I bought mine from the Abe Books Web Site and they cost me about £5 each plus post and packing. I'm certain I have seen the whole series of them priced at £15.

Now to try to answer some of your questions and you have to accept that my points of view might not be the same as of other Forumists because there is very rarely a right or wrong way of doing anything. First, is your greenhouse well ventilated?. Mine, which is an 8' x 6' aluminium greenhouse has two  roof vents both of which are wide open all year round. It also has two louvre vents at around the height of my staging, one each side also fully open all year round. In addition I have taken two panes of glass out of the door and covered the gap with plastic mesh; and one pane of glass out of the elevation opposite the door which is again covered with mesh. This gives me good air circulation and it suits the plants I grow and the natural climate I have to grow them in. I use Coolglass for shading and I shade from end March /early April until, usually early September. I choose Coolglass because it is both readily available and cheap. I could use shade netting but in a greenhouse situation I never found it easy to keep in place (I have a windy garden). Verishade is OK but it is expensive compared with Coolglass.

Your questions:

1. Yes, some alpines will scorch and others will not. It depends on the climate within the greenhouse and what the plant is used too in it's natural conditions. It is probably a generalisation to say that many of the spring flowering alpines appreciate a cooler shady rest during the hotter months and may do better outside the greenhouse. I have some in a north facing situation in an open frame made from old wooden pallets I scrounged from the local supermarket.

2. many plants will scorch in strong sunny conditions if water gets on their leaves or if they get to hot and dry.

3. most of the spring flowering alpines prefer shade in summer and nearly all young plants do better in cooler shade than in the heat of the greenhouse. Some of mine live underneath the staging when the weather is hot.

4. I'm not sure if you mean a plunge in the greenhouse or outside it?

As I said, very much my point of view and I hope some of the others will contribute.