Spring Flowering Bog Plants
While the pool is dull and lifeless during the winter and early spring, the bog garden can retain our interest. Indeed, there are so many different species of moisture-loving perennials that the gardener with a reasonable amount of space has no excuse for not having something in flower at every season of the year.
Take Petasites fragrans (winter heliotrope) for instance. This comes into flower as early, or late, as November and carries on right into March. Its fragrant, lilac-pink blossoms are borne in dense clusters and succeeded by long-stalked, roundish leaves. The larger Petasites japonicus is quite widely grown, but as it has immense, cabbagy foliage well over a metre high it cannot be seriously considered for the smaller garden. However, where space can be spared it is well worth having, its large, crowded heads of scentless white blossoms appearing well in advance of the foliage.
The early spring flowering Peltiphyllum peltatum is of similar aspect but considerably smaller, its globular heads of soft pink blooms being carried on slender stems 45cm high. These appear before the handsome, rounded, bronze-green leaves which are proudly supported on centrally placed leaf stalks.
The charming Cardamine pratensis (cuckoo flower)at around the same time, although it does not associate well with peltiphyllum. Growing to a height of 30cm, this delightful native has attractive pinnate foliage and delicate lilac blossoms, which, in the more compact flore-plena, are fully double. Like a number of other bog garden subjects, cardamine will grow well in either sun or shade.
This could also be said about the moisture-loving primulas, although one or two prefer a little dappled shade. The first species to flower are the tiny Primula rosea and military-looking Primula denticulata. Both provide a bold splash of colour at the poolside during March and April and are easily grown in constantly moist conditions.
Primula rosea never gets more than 15cm high and carries a profusion of intense rose-pink blossoms above tufts of freshly emerging bronze-green foliage which ages to soft green. The cultivar ‘Delight’ is even more lovely and should be grown whenever possible.
Several selections of Primula denticulata have been made, but none can compare with the natural blue and lilac shades of the species. The white form alba, lilac-purple and mealy-leafed cashmireana, and the various red and mauve strains always look rather artificial to me. In fact, the structure of the flower heads, which appear as tight rounded clusters on short stout stems, are not at all easy to incorporate into the general garden scene. Certainly Primula denticulata would present considerable difficulties if it flowered later in the year and had to vie with other plants for attention. As it is now, it can be allowed to flower alone in solitary splendour.
The same sort of problem arises with the later flowering Primula vialii, a striking plant with neat spikes of red and lilac blooms, both in shape and contrast like those of a red hot poker. Even though other plants crave for attention, this extraordinary primula should be given pride of place, being planted with a background of subtle greens such as can be provided by hardy ferns. It is a truly remarkable plant with a rather temperamental nature, but well worth trying to tame.
Candelabra primulas are good-natured and easily placed. Their handsome tiered whorls of blossoms being easy on the eye and readily conforming to most surroundings. They are not solitary plants though, and must be planted boldly in clumps or drifts. Most kinds start flowering during early May and continue well into the summer.
I like Primula aurantiaca with its bright reddish-orange flowers. The purplish-red Primula japonica and its cultivars ‘Postford White’and ‘Miller’s Crimson’, together with the lovely magenta Primula pulverulenta with its attractive mealy stems. ‘Bartley Strain’ is derived from Primula pulverulenta and yields a range of pastel shades which extend from buff through peach to pink, while the later flowering Primula bulleyana has uniform flowers of orange in dense tiered whorls. Primula beesiana and Primula burmanica have blossoms in rosy-purple shades and complete the range of easily grown candelabra varieties.
Primula florindae (Himalayan cowslip) looks rather like an overgrown cowslip and has pendant, sulphureous bells on stems a metre or so high. These arise from amongst coarse, cabbagy leaves which have a delicious aroma. Primula sikkimensis is almost identical, but with much smaller, sweetly scented, soft yellow blossoms, while the more refined Primula microdonta alpicola and its deep mauve variety violacea grow in a similar fashion. These two have much smoother foliage and are readily distinguished by their liberal coating of white or yellowish farina which covers the leaves and extends up the flower stems. Neither grows more than 45cm high and each gives a touch of class to the bog garden.
This can also be provided by the recently popularised Primula sieboldii and its varieties.
Good named varieties in pink and white shades, preferably purchased growing in pots and when they are in flower, are the safest means of ensuring a good show. They produce open floppy blossoms on stems scarcely 30cm high which peep out from amongst lovely soft crimpled foliage.
Primula waltonii grows just a little taller and has clustered flowers of deep port wine red, while Primula cockburniana is short and compact with blossoms of intense orange-scarlet. These two and Primula sieboldii always grow more satisfactorily in light shade and, although requiring moist conditions, will not tolerate the really wet situations enjoyed by Primula florindae and Primula sikkimensis.
Trollius are grand for associating with primulas. Coming into flower variously from late April until mid June, they make a brave show with their incurved heads of bright yellow or orange blossoms on strong wiry stems. Their dark green lobed foliage belies their close affinity with the buttercups, but, fortunately, they do not have the same invasive tendencies. In fact, they are all quite restrained and form tidy hummocks of foliage.
The soft yellow Trollius europaeus and the greatly underrated rich golden Trollius asiaticus are the parents of most modern hybrids, with the occasional intervention of Trollius sinensis. Although all three are of garden merit, their progeny are much improved and consequently more widely planted. ‘Fire Globe’ is deep orange, ‘Orange Princess’ a trifle paler, while ‘Canary Bird’ is rich yellow.