May Flowering Perennial Plants


May is really the month when the perennials begin to take charge of the flower garden. You can, believe it or not, even have an orchid blooming in the border then!



Cypripedium – Lady’s slipper orchid

This is quite an amenable plant, small but hardy, and by no means the heated greenhouse aristocrat many people still seem to expect it to be. You may have some difficulty in getting one — it is a specialist subject — but it will not present any real difficulties provided you can keep it in a cool, fairly damp site. This is one of the comparatively few plants that relish a north-facing situation. Potted up in winter and kept indoors in a cool but not draughty spot, it could bloom very early in the year. Expect it to flower until June. It will grow to about 30cm (1ft).



The perennial dianthus, covering varieties of sweet williams, pinks and carnations, are dealt with in a similar way to the annual version: used with care and determination you can have a continual source of that delightful sweet clovey scent from April to September or October.


Erigeron – Fleabane

This has daisy-like flowers, mostly under 30cm (1ft), and will provide a successional range of colour all summer in white, pink, lavender, orange and mauve. It is very similar in appearance to the aster. Erigeron thrives on sandy soil but will accept any home that is fairly dry and sunny. It spreads rather quickly, so when planting leave at least 30cm (1ft) space between. It is advisable to divide clumps every second or third year.


Gerbera – Transvaal daisy


This is a little larger than the fleabane. It needs a sunny position and is rather tender, so should be lifted and taken into a shed or cool greenhouse for the winter. The G. jamesonii hybrids produce a fine range of yellow-centred flowers in white, yellow, cream, pink and red, providing a grand collection of cut flowers all through the summer. They are easily raised from seed sown in February in a warm greenhouse, and are well worth the slight trouble they cause in raising.


Limonium – Sea lavender

The common name gives the clue as to the type of plant this is. It grows up to 60cm (2ft) high and has tiny pink- or lavender-coloured flowers. It can be started from seed but this is a long process, taking up to three or even four years. Excellent for seaside gardens as it seems to thrive on salt air.


Linum – Flax


The common name immediately conjures up visions of a pretty little blue flower. But lurking under its official name are a host of other colours. The perennial versions come in yellow, white and pink as well as blue, and additionally there are some annual varieties, slightly shorter, in vivid red or scarlet. Be careful also that you place your flax in a sunny position. Near the front of a south-facing rock garden is ideal for the flax will hide its face if it is in shade. But if the sun lasts until September, the linum will stay with it.

The flowers may last only one day, but if you are prepared to dead-head them frequently you will get a continuous supply of bloom. Linum aureum, as its name indicates, is a golden colour, and grows taller than the rest.


Potentilla – Cinquefoil

This is one of the most obliging plants in the herbaceous range. Most are ideal for the rock garden, flowering in dry, sunny conditions from April or May to September, in shades of scarlet, pink, yellow, orange and sundry tints in between. Usually they are less than 30cm (1ft) in height. There are shrubby versions available, but the herbaceous types offer the greater variety of choice and flower. One of the most popular is ‘Gibson’s Scarlet’, which offers the additional attraction of strawberry-like leaves. This is an old variety that regained its popularity only a few years ago and now seems set for a period of prosperity. ‘Miss Willmott’, a little taller, is also red. A golden beauty that will shine from the front of the rockery is Potentilla aurea, which will flower for a couple of months from May onwards.


Saxifraga – Rockfoil

Yet another front-of-border plant that makes rock gardens worth having. The best known variety is probably ‘London Pride’, usually (though not quite accurately) listed as S. umbrosa. Pink flowers in a nest of purplish stems make it an unforgettable sight, which no doubt largely accounts for its popularity. In truth it is rather invasive and does need keeping in check. Very tough, it will flower right through summer into autumn.


Sedum – Stonecrop

A particularly interesting, even entertaining, plant. As the common name indicates, it does bear some slight resemblance to gravel, but the colours of the leaves and flowers make it a very colourful gravel. Sedums rank among the succulents and are widely regarded as plants to decorate the rock garden, but they can have a striking effect at the front of a border. On the whole, they are very short-stemmed. The maximum height is about 30cm (1ft), with the majority barely half this, or even less. They like a sunny position and one of their attractions is the way butterflies flutter around them. Very good for ground cover, the flowers are mostly orange and red but there are some blues and greys. They will provide bloom until October.



A sun-loving plant with several varieties, the best known of which is ‘Silver Carpet’, a grey-foliage plant, ideal for the front of the border, and indeed one of the best of the foliage plants. It is evergreen and makes a perfect contrast to other plants in the border. This one is purely foliage and does not flower but there are other varieties having pink or red flowers, which will last easily until August.



Aquilegia – Columbine

This is a versatile member of the buttercup family, and in its various guises will flower from May till October. The flowers vary from little alpines to tallish, elegant, star-shaped blooms and are ideal for cutting. They prefer some shade but are quite accommodating as to where they live. The dragonfly hybrids are renowned for their colour varieties — red, yellow and copper — which usually bloom from May to July. Follow them with another strain, the McKana hybrids, which have a blue tinge among their colour range, and you will have colour into August or September.




A very colourful plant, though it does not have real flowers, but bracts, which are coloured leaves on a flower stalk. Invariably the flowers themselves are insignificant. Most are yellowish green, but there are exceptions. The aptly named ‘Fireglow’ is a striking orange-red. Given good conditions, some will show their colour in April, but they are at their best from May till July. The poinsettia is the best known euphorbia, though it is not regarded as an outdoor plant in Britain.


Hemerocallis – Day lily

This name means, in approximate terms, `beautiful for a day’ — extremely apt, for there are few plants that can beat the day lily for beauty of flower. While it is true the individual blooms are usually over in a single day, they manage to arrange such a fine succession that you do not notice. They always appear beautiful and fresh, as indeed they are. These plants are truly perennial in the sense that a clump will last more or less for ever. I once had some that were reputed to have been in position for over twenty years undisturbed. They had been planted at the front of a shrubbery that had become overgrown, and understandably they were rather thin and spindly. But they did produce a mass of lovely orange colour, which looked wonderful with the sun shining on them through the leaves of the surrounding shrubs, and I loved them. Nowadays you don’t have to be content with orange as the exclusive shade, as they come in tones of pink, gold and even cream. As for their ‘day’, it is quite a long time: between them they will keep you in colour from May till the end of September.


Kniphofia – Red hot poker; Torch lily

This is not a very elegant plant on its own, but is certainly distinctive with its long upright stem of brightly coloured flowers. These are principally red, of course, but are also now available in yellow and white, and there are experiments with green shades. I like to see them amid a collection of ornamental grasses; the stark brightness contrasts with the subtle tones and quiet grace of the grasses to make a pleasing and strangely restful effect, but they can also be used ‘architecturally’ in a general bed or border.




Here we have one of the aristocrats — not to say autocrats — of the garden. The paeony can be either a herbaceous perennial or a shrubby one. The main difference is that you propagate the first by division (not easy, as the roots are very tough) and the second by layering. Spring or autumn is the time. They will take at least four years before they look anything like the type of plant you expect to see, and they resent being moved. But leave them to show themselves in their own good time and they will repay your patience.

It pays to give them a richly manured bed —they will expect to be drawing nourishment from it for a good many years. Mostly they are a purplish red. ‘Bowl of Beauty’ is probably the best known, and it does carry some perfume. There are some white and yellow varieties, which also enrich the air with their scent. The rather tight flowers last well when cut, and are especially effective in a table decoration.


Papaver – Poppy

Poppies are in a sense the big, blousy, lovable trollops of the border — and that is not meant disparagingly. The paper-thin blooms are certainly spectacular. The Oriental poppy is a great favourite. It appears in several varieties, mostly in shades of red or orange, but there is a white one. Most flower from May to June, but the dwarf Iceland poppy will go on till September. The plants are not long lived, so it may be better to grow them as annuals.



What do you want from a plant: flower, foliage, colour, perfume, longevity? You have it all here. I have tried, in vain, to find a phrase that does justice in describing the wonderful aromatic qualities of the Zonal pelargoniums (still widely but incorrectly called geraniums). It’s not earthy, for that implies a certain mustiness or dampness, nor is it like the damp autumnal smell of chrysanthemums. It is not quite like the cinnamon perfume of the pinks and has none of the cloying sweetness of the lily, or the delicacy of the rose. In short, a good, no-nonsense, exclusive, down-to-earth trademark: one you can recognize without even looking. In fact, pelargoniums are widely used in gardens for the blind, for apart from the ‘basic’ there are special flavours like lemon, pineapple and peppermint.

Pelargoniums can also be grown as annuals or biennials, and are a traditional favourite for the window box, or potted for indoor use. They will enhance any border from May till October, preferring sun with some shade. You can take cuttings at any time and with care have them in flower all the year round indoors on a rota basis. Although red may be a traditional colour, they do produce a wide range, including white, pink and blue. The Zonals have a dark maroon ring on the leaf; the Regals probably produce the better flowers. The trailing ivy-leaf varieties are particularly effective in hanging baskets. Specialist growers will give you a wonderful selection from upwards of 250 varieties.

It is advisable to lift and store pelargoniums in the autumn. Cut them back and store them in pots for the winter. It is important not to overwater them, and also to ensure that the compost is new and fresh when starting new plants. Grey mould is a problem: remove all dying leaves immediately they are seen. Leaf curl is another trouble, which particularly affects ‘Paul Crampel’ and ‘King of Denmark’. It is not a killer, but the leaves become spotted and crinkled, and plants affected will pass it on if cuttings are taken from them.

This does not mean that pelargoniums are more susceptible than other plants to diseases. Far from it, for on the whole they are among the healthiest plants anyone could wish to have. They have one further asset, in their coloured leaves. When the flowers fade or are affected by wet weather, the leaves seem to take over, and they give a marvellous variegated display.



These are plants that offer three-tier joy. They suppress weeds, their leaves form a dense low carpet, and the flowers provide an exuberant foam of colour. The Douglasii varieties (pink, white and mauve) are outstanding for the rock garden: very short, under 10cm (4in). The border types, mostly around 1m (3ft), come in a profusion of both variety and colour. The paniculatas are scented and will keep the garden in perfume from May till September.

28. April 2011 by admin
Categories: Annuals, Biennials and Perennials, Plants | Tags: , | Comments Off on May Flowering Perennial Plants


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