By Cornishsally
Cornwall,
United Kingdom 
I am growing Penstomen 'True Blue' from seed and the seedlings are growing extremely slowly: after six weeks they finally have a second set of tiny leaves. They are on a sunny window sill in the kitchen, and because they still look so delicate I cover the tray with a propagator lid at night. Is there any chance they will flower this year? Am I doing anything wrong or are they usually as slow as this? Thanks for any information.
13 Apr, 2010
Answers
Thank you. They are in John Innes no 2 - I probably pricked them out too soon & was afraid that they wouldn't survive but all of them did. I will just have to be patient!
14 Apr, 2010
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If they are in a completely mineral starting medium, such as vermiculite, you will need to feed them lightly and frequently for growth to continue, at least until you can put them into a more normal potting compost. A coir-based mixture will hold nutrients better, but still usually doesn't have much in the way of nutrients to begin with. So, a little bit of fertilizer may be in order.
Sadly, Sally, in cool climates like yours, Penstemon heterophyllus hybrids like 'True Blue' often need an extra season to reach blooming size.
14 Apr, 2010