Silk tree
These are very attractive flowering trees which grow from Iran to Japan. It was introduced to the UK in 1745. Their delicate, fern-like, light to dark green leaves with many small sickle shaped leaflets do make Albizia look as though they are tender greenhouse plants but this need not be the case in milder locations or even in city situations where there is little frost. A. julibrissin will survive a really good dose of frost once its growth has been fully ripened in a hot summer and its branches have become properly ‘woody’. Alternating mild and cold spells can do more damage. There may therefore be a case for growing this plant initially in a large tub and bringing it in for the winter until it is sizeable enough to properly plant out.
We have flowered A. julibrissin both in the nursery in pots and in the show tunnel. The flowers are in terminal clusters 3-6in wide and are pink in appearance. These appear in late summer or early autumn although, last year, I did see flowers in early July on a mature plant of some 15ft in height (and a similar spread) in a central village on the Isle of Wight.
This is a small tree which needs to be positioned in as frost free a location as possible in full sun where it will get a good summer baking. Perhaps against or near a wall to reflect the sun onto the plant. In this sort of location you may need to prune it into shape from time to time in spring.
Plants in the UK will not set seed often and propagation is easiest from root cuttings in winter. If you do purchase seeds these need to be soaked in warm water for 24 hours before sowing.
Over the years we sometimes have young plants of A. julibrissin ‘Ombrella’ which has deeper pink flowers and A. julibrissin ‘Summer Chocolate’ which has startling maroon to bronze-purple foliage and pinkish-purple flowers with light centres.
Red spider mite can be a problem if these plants remain in the greenhouse for years. It is best to stand them outside in the summer months to avoid the problem.
