Hardy Annuals

Growing hardy annuals as a feature in them-selves has gone out of fashion, owing to the small size of most modern gardens and the fact that people prefer a more permanent scheme that does not have to be renewed each season. But for anyone faced with a bare plot and wishing to have colourful flowers quickly, hardy annuals still have much to commend them. Indeed, there is nothing to beat them for providing the maximum amount of colour at minimum cost in the shortest time. They are ideal, too, for growing between shrubs and trees for a season or two until the permanent plants need all the space allotted to them, or for filling any awkward gap that may appear in a bed or border.

To get the best effect, choose those hardy annuals that can provide massed colour. This means excluding plants such as larkspur (Delphinium), which, although it is stately and makes an excellent cut flower, does not keep up a long show. You should also take care to position them so that short plants are not hidden behind tall ones and in such a way that those with flowers of similar shades are separated by those of other colours.

If you intend to devote a whole bed or border to hardy annuals alone it is best to sow them in large irregular patches of each kind, rather than a few here and there. Also, arrange them so that the edges of the groups are staggered rather like those of bricks in a wall so that there are no distinct dividing lines running from front to back, or from end to end, of the bed.

It saves time and prevents mistakes if you draw up a rough plan beforehand showing where each variety of annual is to be sown, giving its height and colour. Then, once the ground has been raked and prepared for sowing, the outlines of the different areas can be marked out on the soil and each sown with its allotted plant.

In general hardy annuals are not fussy about the type of soil, making as good a show on sandy ground as they do in clay. It has often been asserted that they flower best on poor soil, although in my experience this is only half true. You get a much more rewarding display from plants that have sufficient food to grow to a proper size. On the other hand, hardy annuals must never be given a lot of fresh manure or nitrogenous fertiliser, such as nitrate of soda, both of which tend to lead to rank growth with luxuriant foliage and poor flowering. I find that if a little general fertiliser, such as the Growmore devised for vegetables, is worked into the ground while preparing it for sowing, this will suit these flowers very well unless the soil is naturally rich. In most cases, however, the key to good flowering is adequate sun.

Hardy annuals vary in size from those that make ground-hugging mats to plants 1m (3-1/4ft) or more in height, and come in the widest range of colours. If your aim is to be as labour-saving as possible, and especially if your garden is exposed to wind, restrict your choice to those that do not exceed a height of about 400 mm (16 in) to avoid having to support them with canes.

Many of these plants are offered in several distinct colours as well as in mixtures. Where a number of them are being grown in association, my preference is to choose individual colours as far as possible, since too many mixed selections give a spotty effect rather than a rich, bold display. But if a single species of annual is sown in isolation, between some shrubs perhaps, a mixture can be charming.

In recent years some of the old and best-known annual flowers have had their botanical names changed. For instance, the familiar white alyssum, which was as much favoured for edging beds in summer in our grandparents’ time as it is today, should now properly be called Lobuiaria maritima, although its old name (Alyssum maritimum) is still occasionally to be found. Its common name, ‘white alyssum’, continues to be used in the seed trade. Where possible, I shall use the names you will find on the seed packets or in nurserymen’s catalogues, even though they may have derived from Latin names that have been changed.

Selection

Although often raised under glass and sold as a bedding plant, white alyssum is a hardy annual that can be sown in the place where it is to bloom. Each plant makes a tidy mat covered with clusters of small flowers for most of the summer. The seedlings are rather slow to develop at first, but an April sowing of the white cultivars will make a good show from mid-summer onwards. Less vigorous, and therefore making smaller plants, are some of the coloured ones, such as the violet-purple ‘Oriental Night’. I find it best to thin these out to intervals of no more than 100 mm (4 in) when they are sown out of doors. This annual is actually a member of the brassica (cabbage) family, and so the seedlings need to be dusted once or twice with derris dust to ward off flea beetles, a typical pest of brassicas, that could check their growth.

sow Iberis where it is to flowerCandytufts (Iberis), with their crowded heads of flowers in white and shades of pink, are always dependable for a good show. They are sown in March or April and attain a height of about 300 mm (1 ft). Less commonly seen is the ‘Giant Hyacinth Flowered White’ cultivar, which grows a little taller because the flower heads are conical instead of flat. So dazzling is the white of this variety in the sunshine that the blooms remind one of silver fireworks.

At 1-1.2 m (3-4 ft) high, Agrostemma milas is among the tallest annuals and is very showy. The large, lilac-pink flowers are carried on wiry stems and are unharmed by rain, although they need the support of a few canes and string to keep them upright. The flowers are marked with thin, dark, broken lines that resemble machine stitching. The plant is easy to grow and makes a good flower for cutting.

Because they look more like exotic shrubs than plants, many people would not recognise the annual mallow (Lavatera) as plants raised from seed to flowering in a matter of weeks. The flowers are large – up to 100 mm (4 in) across – trumpet-shaped, and very similar in appearance to hibiscus. Until recently the only colour available was a rather harsh cerise. Now there are two very attractive cultivars in ‘Silver Cup’, with blooms of cerise streaked with silver pink, and ‘Mont Blanc’, a slightly smaller, white-flowered one. Both make sturdy self-supporting bushes some 600 mm (2 ft) high and do well even in a cool, wet summer. Since they have so much growing to do, they are later flowering (July to September) than most other annuals; but once they start blooming their trumpets open in profusion. Nor is there any need to hide them at the back of a border, because the larger part of each bush is covered in flowers.

Anchusa capensis ‘Blue Angel’, sown in April, is a relative of the tall perennial border plants of the same genus. It grows only 230 mm (9 in) high, however, producing long sprays of small flowers of rich blue for most of the summer. When in full flower it is difficult to see any leaves at all, and it is an ideal plant for a massed effect.

Among the most brilliant of the yellow annuals, the flowers of Mentzelia lindleyi (the preferred synonym for Bartonia aurea) are shining gold and shaped not unlike those of St John’s wort. The plant flowers for a long time, the blooms opening in succession from early June, but the plants are never smothered with them. The one trouble with the plants, I find, is that they tend to straggle. They therefore look better in isolation rather than grown with other annuals. The height is usually around 600mm (2ft).

Easiest of all annuals to grow must be the pot marigolds (Calendula officinalis). Ranging in height between 300 mm (1 ft) and 600 mm (2 ft) they can produce brilliant displays in shades of yellow and orange. Particularly useful in a border sown with annuals are those cultivars with off-beat shades, such as ‘Apricot Beauty’, ‘Cream Beauty, and ‘Pacific Beauty’, a mixture that includes apricot, cream and primrose as well as orange and yellow. Left to themselves pot marigolds set seed with abandon and can become an annoying weed on sandy ground.

One of the most gorgeous summer blues is provided by the cornflowers (Centaurea cyanus), which grow to 300-900mm (1-3 ft) high, depending on variety. For garden decoration I much prefer the short ones because they are tidier. An intriguing colour range is provided by ‘Polka Dot’, with flowers in shades of maroon, rosy red, pink, and white as well as blue on bushy plants a little under 450 mm (18 in) tall.

lavateraAn unusual (although easy to obtain) annual is Crepis rubra. Rather like a pink-flowered dandelion, it produces a terrific display of blooms in August. The only problem is finding the right position for it, because its soft colour looks washed-out if you grow it anywhere near flowers of a stronger pink colour. Although the plants make rosettes of leaves on the ground, the flowers are held some 300 mm (12 in) above the soil.

Quick to flower after sowing, the star-of-the-veldt (Dimorphotheca aurantiaca) is an annual to grow in the sunniest spot available, where its daisy flowers will open and sparkle from June to September. The colour range runs from orange to white, including apricot and lemon. Height is usually around 300 mm (1 ft) or a little less, although the cultivar ‘Glistening White’ may be little more than half as tall.

Linaria or toadflax (Linaria) is one of the smaller annuals; it grows no more than 300 mm (1 ft) high, yet it is exceedingly useful for filling odd spaces as well as being worthy of a place in an annual border. Quick to flower from seed, the tiny blooms (June to July) resemble small snapdragon flowers in appearance. Quite the most striking cultivar I have grown is ‘Crimson and Gold’, a colour combination that draws the eye from a great distance.

Viper’s bugloss (Echium lycopsis, synonym E. plantaginium) is a very well behaved annual, making bushy plants some 300 mm (1 ft) high. Once it starts to bloom the bell- shaped flowers open in succession along the lengthening stems, so that the old ones are always hidden. Hence it looks neat through-out the flowering season from June to August. I much prefer the ordinary ‘Blue Bedder’ to the mixed colours. The colour is nowhere near as bright as that of cornflowers or anchusa, but a more restful, misty blue.

When it comes to the Californian poppies (Eschscholzia californica), however, I much prefer the mixtures, which provide some particularly attractive shades from June to October. The pick of the bunch is the 300 mm (1 ft) tall ‘Ballerina’, with fluted double and semi-double blooms in gorgeous colours. Not the least attraction of the Californian poppies is their dainty grey-green foliage. An unusual but charming edging to a bed can be provided by ‘Miniature Primrose’, a cultivar only half as high as ‘Ballerina’, with small prim-rose-yellow flowers.

Godetia (G. amoena whitneyi, syn. G. grandiflora) is another annual that makes a bushy plant; it is covered from June to August in pink, red, or white flowers, many being patterned or striped with a contrasting colour. Height can be anything from 230 mm (9 in) to 600 mm (2 ft) according to variety; I find the shorter bedding mixtures stand up best. There are a number of cultivars offered, such as ‘Crimson Glow’ and ‘Kelvedon Glory’ (a salmon-orange shade). I have a soft spot for ‘Sybil Sherwood’, with its flowers of salmon-pink edged with white, but I find that even this moderately short cultivar benefits from a little support.

Even shorter is the poached-egg flower (Limnanthes douglasii), an annual that is in the 150-230mm (6-9 in) range. Its five-petalled flowers can be described either as white with a yellow centre or yellow tipped with white; you can take your pick. Although a native of California it is bone hardy and is one of the most reliable annuals for sowing in autumn to gain on extra early display the following year, when it will flower from April to June. Sown in spring it will flower in the summer months.

Among the most reliable annuals, the willowy plants of scarlet flax (Linum grandiflorum ‘Rubrum’) gently bow to the lightest breeze. Their height is around 450 mm (18 in) and they are smothered with brilliant crimson flowers in summer. Equally reliable, although usually a little slow to get started, is love-lies-bleeding (Amaranthus caudatus). The plants are bushy and grow some 800 mm (32 in) tall, but they should not be hidden behind anything because the long swages of crimson tassels (June to October) drape the plants to the ground. The green-flowered variety, ‘Viridis’, is much loved by flower arrangers, but its tassels are never as well developed as those of the ordinary crimson kind, nor do they create such an air of plush Edwardian opulence.

My vote for the most useful annual would go to the ‘Dwarf Jewel Mixture’ cultivar of the nasturtium (Tropaeolum majus). Unlike older cultivars, which tend to hide their blooms with lush foliage if the season is too wet, the soil too rich, or the site too shaded, this one holds its flowers above the foliage. About 300 mm (1 ft) high and bushy of growth, the plants can be used as an edging or as a bedding display, or they may be grown in tubs, window boxes, hanging baskets, or anywhere else that their lemon-yellow to crimson flowers (June to September) will bring a touch of brightness. They are useful, too, in that their light-green, rounded leaves make a good contrast with those of many other plants. One thing to remember about nasturtiums is that they are sometimes attacked by caterpillars of the cabbage-white butterfly, although this pest is easily repelled if the plants are sprayed with derris at the first sign of attack.

mixed bed of hardy annualsWhile all the annuals mentioned so far are grown for their flowers, in the clary (Salvia horminum) it is the bracts (modified leaf-forms) that provide the colours of bright purple, pink, and white. The display is very long lasting and the pink form, in particular, shows up well. The plants are quite bushy and grow about 450 mm (18 in) high. The stems, including the insignificant flowers June to September), can be cut and dried for winter decoration indoors.

For a special treat, grow a few small patches of night-scented stock (Matthiola bicornis) about the garden, especially under the house windows or beside a patio where you may sit out on a warm summer’s evening. Do not give them a prominent position, however, for the small mauve flowers are not at all showy and the plants can become decidedly tired-looking during the day. As night approaches, however, they release a deliriously heavy, sweet fragrance that drifts far afield on the evening air.

Cultivation

Raising annuals from seed is not at all difficult provided you remember the following points. After being dug the ground must be firmed by treading, and then well raked to make a seed bed. Small seeds must not be sown too deep – about 15 mm (1/2in) is suitable for the majority, but the really tiny ones, such as those of Linaria and love-lies-bleeding, should be barely covered. Firm the soil over the seeds by tamping it down gently with the head of a rake, and ensure the ground does not dry out before the seedlings have emerged.

Sowing annuals in shallow drills is far more satisfactory than scattering the seeds over a broad area, since you can hoe between the rows to keep down weeds. When the seedlings emerge, thin them out in stages, removing the weakest ones each time until they stand at intervals of about two thirds of their expected height; the rows should be similarly spaced.

Any necessary supports for taller plants must be put in place in good time. Bushy sticks of suitable length thrust into the soil between the plants while they are still quite small, so that the plants can grow up between them, is a very effective method, but such sticks are unlikely to be available except in rural areas. Alternatively you can use thin, green split-canes with string to form a mesh through which the plants can grow. Only those annuals likely to grow more than 600 mm (2 ft) tall need proper canes to hold them up. Even then it is better to arrange a mesh of supporting string or wires to contain the plants loosely rather than individual canes to support each plant. If the supports are inserted in time for the plants to grow around them naturally, the canes and wires will be well disguised, if not hidden.

The usual time for sowing hardy annuals is in April or early May, and most of them will start to flower in June or July. Some, however, are tough enough to be sown in late August or September, which results in larger and earlier flowering plants the following year. With the exception of Anchusa, Mentzelia (Bartonia), Crepis, Dimorphotheca, Lavatera, Linum, love-lies-bleeding, Matthiola, and nasturtium, all the plants I have mentioned in this article can be grown in this way to extend the period when annuals will provide colour in your garden. But whenever you sow them, remember that quick germination is the first vital step to success. If the soil seems to be rather dry, flood the drills with water and allow it to drain away before scattering the seeds along them.

The summer bedding plants that one buys by the boxful or in pots provide some of the most brilliant displays of flowers during those warm summer days when we spend a lot of time out of doors. Most of these bedders are what gardeners call ‘half-hardy’. This means that they can be grown out of doors but are killed by frost, so it is not safe to plant them in the garden until the likelihood of frost is past. In most of southern England the last week of May is usually considered safe; farther north it pays to wait another week or 10 days before planting out.

02. July 2013 by Dave Pinkney
Categories: Annuals, Plants & Trees | Tags: , , | Comments Off on Hardy Annuals

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