Wisley's Alpine Diary
This entry: 28 May 2010 by Paul Cumbleton
Wisley's Alpine Log
By Paul Cumbleton
2010: Log 73... 28 May
As recent warmer weather has accelerated growth, damage caused by the late frosts earlier this month has become increasingly apparent. Plants all over the garden are showing some die-back of the younger growth, such as in the Rodgersia above, the Acer and the Gunnera (below). Gladly this is just cosmetic damage and the frosts were not severe enough to actually kill anything, but it has spoilt the appearance of a lot of plants.
On a cheerier note, the past month has seen a real riot of colour both in the Display House and outside on the rock garden. Anita Drury looks after the evergreen Lewisia collection and her plants of Lewisia cotyledon hybrids have been superb throughout May. This is a part of the collection, just now passing their peak:
Large numbers of these have been out on display such as this lovely bright pink form:
I have always liked the orange shades, while the over-the-top reds appeal to others.
I gave a brief account of how Anita grows these back in Log 5 of 2008. I?ll repeat this here to save you looking it up:
Growing season: Approximately late February to late September
Compost: They prefer a neutral to acidic mix. We use 2 parts John Innes, 1 part peat, 1 part perlite (or grit or a mix of the two). In our efforts to reduce peat usage, Anita is now trying some with composted bark replacing the peat fraction of the mix.
Repotting: We do it in late February, though seedlings are best potted on 2 or 3 times during their first growing season so they never get a check from being root bound.
Watering: Keep just moist from October to late February (this is their dormant period though they retain their leaves while dormant). Start to increase water from late February (the centre of the rosette often turns a brighter, shinier green when growth recommences and this can be used as a guide as to when to repot and to start increasing the watering). Water normally through the growing season and reduce to keep just moist again by the end of September. During very hot weather watering should be reduced to a bare minimum (the succulent leaves keep the plant going and they are not expecting rain in hot periods. Keep them too wet at such times and they will rot). Try to keep water out of the centre of the rosettes to prevent rotting.
Feeding: Give an occasional liquid feed (e.g. Phostrogen) whilst in active growth
Light: Prefer a partially shaded position
The Lewisia cotyledon hybrids are now available in a huge range of colours, of which the following picture gives just a taste. Surely something here for everyone!
A taste too now of just a few things outside that have been good this past month. In the woodland area Tiarella ?Spring Symphony? has been lighting up a dull corner:
The Phloxes as always have looked good in May. Here is just one example:
Last year we planted out groups of Primula sieboldii cultivars in the moist areas next to the ponds. They have performed magnificently and given long-lasting colour.
Finally, even our mess room was brightened up by Mia Laucht, one of our trainees, using a bowl of colourful auricula flowers floating in water: