By Nariz
Spain 
I have several healthy-looking Penstemon seedlings and - since snails chewed off all the information from the empty packet I'd left with them - am now at a loss to know what conditions they like! Sun or semi-shade? Plant deep? Soft composted soil or can they handle stones? B****y snails! I'll keep the information somewhere else in future!
5 Jun, 2012
Answers
Wow! That was quick - and so concise! Thanks Drc! I'll get to it immediately :o)
5 Jun, 2012
your welcome Nariz
5 Jun, 2012
I tend to plant mine in full sun in a gritty compost because of my clay and water till established.
But here are the Cultivation notes from The RHS
Border penstemons are easy to grow in any fertile, reasonably moist, free-draining soil in full sun or light shade.
Planting is best done from mid- to late spring. Enrich the soil with about a bucketful of well-rotted organic matter and 70g per sq m (2oz per sq yd) of balanced general-purpose fertiliser to aid good establishment. Alpine and shrubby penstemons need relatively infertile soils, so no improvement is needed. Allow 45cm (18in) between plants.
Watering of well-established plants in medium to heavy soils should be seldom needed, but plants growing in light, free-draining soils might need watering every two weeks in dry spells.
Deadheading to remove spent flowering spikes helps promote a long season of flowering.
Aftercare is important to ensure a good show is subsequent years. Each spring apply a balanced, general-purpose fertiliser at the rate of 70g per sq m (2oz per sq yd), followed by a 5-8cm (2-3in) mulch of well-rotted organic matter to help promote strong healthy growth. Penstemons flower on new vigorous growth that is not lush.
Hope this helps.
5 Jun, 2012