These are so colourful, so perfect.in form, with pretty foliage fully complimentary to the, that it would be worth a little trouble to contrive the right growing conditions in a garden where they do not naturally exist. The plants themselves in all cases are tough and hardy, but without moisture and preferably some shade as well, they fall well short of the of which they are capable. Moisture is more important than shade, yet this does not mean they should be treated as bog plants, but merely that they should not be allowed to dry out.
Rich soil—plenty of peat and, with an mulch when dormant, will go a long way to making good any moisture deficiency and some shade or shelter from strong winds holds them longer in flower. To enrich the soil is no problem, and a fairly simple method of providing extra moisture is easy to arrange as well. Tins—about quart size with a few holes punched in the side and bottom, can be inserted unobtrusively here and there between plants, to within an inch or less of the surface. One tin or a 12 inches long drainpipe will irrigate at least three plants and all one has to do is to fill this up with water during droughty weather every other day, and moisture will percolate to the thirsty more effectively than overhead . The same method can of course be applied for the other moisture loving plants mentioned here.
Astilbes vary in height from 4 inches to 6 ft., and even the tallest need no staking. They go completely dormant in winter and from April onwards theappear and develop, all deeply cut and often purplish or bronzy green. Flowering begins in June and for several weeks they are very colourful indeed. In the middle height range of 2-3 feet, A. ‘Fire’ is aptly named, with even deeper reds in A. ‘Glow’ and A. ‘Red Sentinel’. A. ‘Cologne’ is bright pink 2 feet tall, whilst A. ‘Bressingham Beauty’ is a little softer shade, growing to 3 feet. A. ‘Amethyst’ purple, and A. ‘Ostrich Plume’ has pendant spikes of bright pink. These and several more including the 2-2!/2 feet whites A. ‘Deutschlana’ and the dark leaved white A. ‘Irrlicht’ are extensively used for forcing as pot plants. But in the garden where height variations are important there should be room for such beauties as A. tacque-tii superba. This grows to a stately 5 feet, with dark outspanning foliage and no’ble spikes of bright rosy purple with a long season in flower. Also tall, and excellent as waterside subjects, there is the rosy lavender A. davidii and the pale pink A. ‘Venus’ with A. ‘Salland’ a deeper pink. Amongst these hybrid Astilbes are some that carry dense plumes above mounded foliage. A. ‘Fanal’ and A. ‘Etna’ are red, rather similar to each other, and A. ‘Federsee’ is intense salmon pink. A. ‘Mainz’ is lilac rose and ‘Intermezzo’ a fine salmon pink. The species A. simplicifolia has added its quota to the range of hybrids. The type is pretty, with graceful pink spikes 15 inches tall, but the variety atro-rosea is superb, carrying sheaves of tiny bright pink flowers for a long time. There is white in this range and a charming dark leaved pink variety only 9 inches high, called A. ‘Bronze Elegance’. For this and the salmon A. ‘Dunkelachs’, shade as well as moist humus is needed, but A. Sprite’ is more adaptable. This is darkly leaved and the sprays carrying myriads of tiny flowers of pale shell pink make a most effective combination, growing 12 inches high and at least 12 inches across. One other species should be mentioned—A. sinensis pumila. This has a creeping habit of fresh, crispy leaves, close to the ground and stumpy 12 inches spikes of a lilac rose colour, and it is less fussy about moisture than most.
This along with A. tacquetii superba for a tall one, and A. ‘Federsee’ for medium height can be recommended as a trial selection for those who are dubious and not having grown them before. In my experience their moisture requirements are not so critical, but it should be added that only in summer droughts does this need for moisture exist, and even if witheld, the plant will survive for another season. Given anmulch, plants can be left down for years, but can also be divided when old and dormant without much difficulty.