How to grow Annual Flowers

How to grow Annual Flowers

Hardy annuals are easy to grow and will give a quick and brilliant display provided they are grown in an open, sunny position in any good garden soil. Many annuals are tender and easily killed by frost, so these kinds are sown under glass in the spring and planted out when all danger of frost is over. Some hardy and half-hardy kinds make excellent pot plants for the greenhouse and there are others that need greenhouse cultivation entirely.

Some, such as the nasturtium, flower better if grown on rather poor soil. Most annuals will make too much leaf growth if grown in soil that is too rich or in shady places. Their rapid growth makes them invaluable for the new garden when flowers are wanted the first year, or for filling gaps in newly-planted herbaceous borders. Some, such as trailing lobelias, dwarf nasturtiums, and petunias are useful plants for hanging baskets. Many are useful for providing color in urns, terrace pots, window boxes, tubs, and other plant containers. Certain low-growing annuals find a place in carpet bedding schemes such as are still found in public parks. Although the purist may frown upon their use in this way, a few annuals are suitable for the rock garden.

A number of annuals have very fragrant flowers. Some have flowers or seed heads which may be dried for winter decoration indoors.

Some annuals, including a number of those used for carpet bedding, are grown for the sake of their colorful foliage.

Apart from removing faded flowers, keeping them weeded and staking the taller kinds of annuals need little attention, and they are a quick and inexpensive way to provide masses of summer color, especially in a new garden.


Of all the operations that contribute to successful gardening, the correct planting procedure is one of the most important. Digging a hole, pushing in the plant, and hoping is not enough. Any gardener who does just this is doomed to constant disappointments.

Before the actual planting is carried out, careful preparation of the site is necessary, whether the project involved is an extensive border, the planting of a bedding scheme, or the tiniest pocket for an alpine plant. Beds, borders, or planting holes should be deeply dug before planting. As far as beds and borders are concerned, full-scale trenching is best although nowadays, most busy gardeners settle for double-digging, or bastard trenching as it is sometimes called.

The surface soil must be broken down to a tilth of a fineness appropriate to the size of the specimens which are to be planted. Obviously, the ground for trees and shrubs will not require such careful preparation as it will for annual bedding plants or alpines.

As well as being thoroughly broken down, the soil should be in good heart.

This means that it must contain enough humus and plant foods for the initial requirements of whatever is being planted. This can be achieved by digging in adequate quantities of humus-rich materials such as peat, leafmould, well-rotted garden compost, or animal manures.

These can be supplemented by a dressing of a slow-acting organic fertilizer such as bonemeal or steamed bone flour, forked into the topsoil a week or two in advance of planting or, where individual plantings are concerned, sprinkled into the holes.

Different kinds of plants will obviously need different planting procedures. The smaller they are, the more carefully should the operation be carried out. Appearances, however, can sometimes be deceptive. Nothing could look more delicate and vulnerable than a seedling that has just made its first pair of true leaves. And yet, at this stage—the best stage for planting out most seedlings—they can be surprisingly tough, perhaps because transplanting causes less damage to their rudimentary root system provided that they are transferred, without undue delay, from seed pans into boxes or nursery beds.

Seedlings should be handled gently, yet firmly, easing them carefully out of the seed compost and grasping them firmly by the leaves between thumb and forefinger as you plant them out in their new soil.

After this operation, particular attention should be paid to watering. Little and often is the rule to follow. Over-watering can cause damping-off, but seedlings should never be allowed to dry out completely; this can prove equally disastrous.

Planting annuals and bedding plants

It is important to success when planting annuals, to ensure that they receive an as little check as possible; they will then start into active growth again almost immediately. Whether plants come out of boxes, pots or nursery beds, it is always better to wait for a day when the soil is moist (but not soggy) after rain and when the atmosphere is humid. In these conditions, the plants will lose little moisture through transpiration.

If planting out time should coincide with a long dry spell, the only course is to soak both plants and planting holes with water a few hours in advance. The water should be allowed to drain away from the holes before the plants go in. As soon as the soil is friable and the weather favorable, hardy annuals should be sown where the plants are to flower. These quick-growing plants are excellent for ‘gapping’ in a new herbaceous border where the perennials are still small. If the ground was not prepared last month, the area to be sown should be marked off with short sticks at once, the soil forked over and plenty of damp horticultural peat added to the top 2 or 3 inches. Soil for seed sowing needs to be very fine for good germination.

So the surface should be well raked down to a sand-like tilth before scattering the seed thinly, broadcast or in drills, just covered with soil. Twiggy sticks placed over the newly sown area will deter birds and prevent cats using the soil as a scratching ground.

Bedding plants should never be out of the ground for any length of time. They can suffer a serious check if they are left lying in the sun or in drying winds. The ideal course is to get them straight from box to bed. This is a difficulty that does not arise with plants that are set out from pots.

When planting from seedboxes, the roots of each individual plant should, if possible, be carefully disentangled from those of its neighbors. This will minimize damage and enable the plants to get away again quickly.

Some hardy annuals may be sown in August or September to flower early the following summer. As soon as the seedlings are large enough to handle they should be thinned. With autumn-sown annuals leave the final thinning until the following spring. Distances apart vary considerably, depending on the ultimate height of the annual, but as a general guide, dwarf-growing annuals should be thinned to 4-6 inches apart. Those that grow to 15-18 inches tall should be thinned to 9-12 inches and taller kinds should be thinned to 1-2 feet apart.

If a seed is wanted for sowing again next year it is best to mark a few good plants early in the summer. The seed-heads should not be gathered until they are fully ripe.

Half-hardy annuals

Some annuals and a few perennials treated as annuals will not stand frost, so they are sown under glass in pots, pans or seedboxes, using seed compost or soil-less seed compost.

Sow the seeds thinly and cover and then place a sheet of glass and a piece of brown paper over the pot or box. Turn the glass daily to prevent condensation drips from falling on to the soil. Remove the paper as soon as the seeds germinate but leave the glass on for a further few days, tilting it slightly to admit some air.

When the seedlings are large enough prick them out into boxes of potting compost or a soil-less potting compost and shade them for a day or two from strong sunlight.

When watering seedboxes it is best to immerse them in water up to their rims until all the compost is thoroughly damp.

i.e., when the surface has darkened. This method is preferable to watering overhead. Where a soilless seed compost based on peat and sand is used the initial watering usually suffices.

It is essential to harden the plants off well before they are planted out into their flowering positions at the end of May or the beginning of June. Transfer the boxes to a cold frame and gradually increase the ventilation, eventually leaving the lights off altogether except on nights when frost is likely. If a frame is not available, gradually increase the greenhouse ventilation, finally leaving doors and vents open day and night.

It is a great mistake to sow too early under glass as this simply means that the plants receive a severe check by becoming over-crowded in their boxes while waiting to be planted out into their permanent positions.

The damping-off disease at the seedling stage can be troublesome but it can be controlled to a very large extent by using sterilized or soil-less composts and by watering with the Cheshunt compound.

It is also possible to sow half-hardy annuals in the open ground in May or early June and, flowering later, they extend the flowering season.

Greenhouse annuals

Many hardy, half-hardy, and tender annuals make colorful plants for the cool greenhouse. They may also be grown in this way for cut flowers; or the pots, when in flower, may be taken into the house.

A seed is sown as for half-hardy annuals in pans, pots or boxes and the seedlings are potted up when they are large enough to handle. Pot-on as soon as the roots fill the pot. Some annuals resent being transplanted so it is best to sow these straight into their flowering pots and thin out the seedlings later.

The great advantage of a greenhouse for annuals is that flowers may be had throughout the year by sowing at different times. The temperature when sowing should be about 65°F (18°C), but it is not necessary to maintain this high temperature afterwards, provided the greenhouse is completely frost-free. Many of the greenhouse annuals will need their growing points pinched out to encourage bushy plants and some will need staking. Water liberally in the summer months but moderately in the winter, and feed the plants with weak liquid manure at regular intervals.

Many seeds of annuals can be sown directly into patio pots to give vivid
color later in the year and spring is the time to sow them. Seed is generally so inexpensive and readily available that a few failures are of no major significance. Alyssum, candytuft, nigella, campanula, mignonette, Virginian stock, wallflowers, forget-me-nots, pansies, Anemone japonica, London pride, armeria, arabis and many others are suitable and effective.

Choose low-growing plants rather than tall and make sure always that they do not get too dry at the roots.

As in the open garden, the greatest effect is to be obtained by planting colors in concentrated blocks rather than scattering them indiscriminately like confetti. Annuals are cheap and instantly effective, so here, according to color groupings, are brief selections of low growing annuals suited to window-boxes as well as container plantings on patio, balcony, and roof garden. Some flowers, of course, come in several different colors, so they may be listed more than once.

White: alyssum, begonia, daisy, candy-tuft, Celosia nana, dianthus, echium, eschscholzia, forget-me-not, gazania, linaria, lobelia, mignonette, nemesia, nemophila, pansy, petunia, Phlox drummondii, polyanthus, portulaca, Virginian stock, verbena.

Yellow: Celosia nana, eschscholzia, gazania, leptosiphon, limnanthes, nasturtium, nemesia, pansy, polyanthus, Tagetes signata, wallflower.

Red: anagallis, begonia, Dianthus sinensis, eschscholzia, leptosiphon, mignonette, nasturtium, nemesia, petunia, Phlox drummondii, polyanthus, portulaca, Silene pendula, Virginian stock, verbena, wallflower.

Blue: anagallis, anchusa, echium, forget-me-not, lobelia, nemesia, nemophila, pansy, petunia, phacelia, polyanthus, Virginian stock, verbena, viscaria.

Choose boxes of plants that are showing color but which also have many buds waiting to open. Inspect them carefully to ensure that there is no disease present and that the soil is moist. When you get them home keep them in a cool and shady spot until you are ready 1 to plant them.

Have your containers ready with soil, either potting compost or one of the proprietary no-soil mixtures. Water the boxes of plants again a few minutes before planting and then lift each plant out carefully with a good ball of soil adhering to the roots. Plant with a trowel, spreading the roots well and firming the soil over them. Water again thoroughly until water begins to trickle from the drainage holes. Leave the newly planted containers in shade for a day or two before bringing them to their final positions.

Once the plants are growing away well, examine them each day for disease, water regularly and pick off all dead flowers to ensure a continuity of bloom. Any plant that dies should be removed at once, both for the appearance of the container and in case the dead or dying plant spreads its infection to its neighbors.


There are certain flowers which are particularly suited to cloche cultivation. These can be brought into bloom several weeks earlier and the quality of the flower is often much better. Hardy annuals, in particular, are ideal plants for cloche protection during the early
stages of their growth. The most important of these are sweet peas.

Sweet Peas

Sowing time for sweet peas in the north and south is late September. Seed can also be sown in March. The strip of ground should be deeply worked and plenty of organic matter incorporated in the form of peat, old manure or composted vegetable waste. A seed is sown one row per small cloche and two under the larger types. Space the seeds 6 inches apart in the rows. Cloches must be placed over the rows as soon as the seed is sown in the north. Southern sowings need not be covered until early October.

As soon as the plants are a few inches high, they should be provided with pieces of brushwood, through which they will grow. If large flowers are required, plants should be grown in the cordon system. Only the strongest side-growth is allowed to grow on after the initial stopping, and this growth should be trained up a strong case. Plenty of water is required during the summer. There are so many beautiful, reliable varieties that a selection should be made from a specialist’s catalog.

Other hardy annuals

Those suitable for cloche work and autumn sowing include calendula, candytuft, cornflower, scabious, viscaria, sweet sultan, and nigella. For spring sowing the following are recommended: godetia, mignonette, and clarkia. A seed is sown in groups as thinly as possible or in single rows. Large cloches can accommodate two rows.

Halfhardy annuals

These benefit considerably from early covering after they have been sown in early April. Seed is sown thinly in single or double rows according to the size of the cloche. Final thinning is from 8-12 inches apart. Suitable varieties include zinnias, schizanthus, nemesia, nicotiana, petunia, and dimorphotheca.

Fragrant annuals

Those in search of fragrance are more likely to find it among the annuals and biennials than among the hardy perennials, for it is a quality possessed by many of the plants that are raised from seed sown in the spring, either under glass or in the open ground. Of these undoubtedly the most popular is the delightfully fragrant sweet peas, varieties of Lathyrus odoratus. As with other plants, the fragrance varies a good deal but a good seedsman’s list will make a point of describing those which possess it more strongly than others. Among other annuals and biennials which have it are Sweet Alison (Lobularia maritima), wallflowers (cheiranthus), snapdragons (antirrhinum), ten-week, Brompton and East Lothian stocks (Matthiola incana), night-scented stock(Matthiola bicornis), marigolds (calendula), nasturtiums (tropaeolum), mignonette (Reseda odorata), Sweet Sultan
(Centaurea moschata), the sweet-scented tobacco plant (nicotiana), sweet scabious (Scabiosa atropurpurea), annual lupins, and the biennial evening primrose (Oenothera odorata). All of these are popular with most gardeners, but less well known, perhaps, is the Marvel of Peru (Mirabilis jalapa), a half-hardy annual with small trumpet-shaped flowers in various colors, their fragrance identical with that of the sweet-scented tobacco plant. Cleome spinosa, the spider flower is another less common annual, 3 feet or so tall, with spidery-petalled pink or white flowers that add fragrance to their other attractions.

Bedding out

This term, in use by gardeners, describes a form of gardening in which plants raised elsewhere in a nursery garden or greenhouse are planted in a previously prepared bed.

The description bedding plant is not an exact one and only means that the plant is grown elsewhere in some quantity and then planted out as a temporary occupant of the bed; this being known as `bedding out’.

The bedding plant in private gardens has, in general, had its day, since this style of gardening entails much expertise.

In public gardens and for certain formal occasions the bedding plant still has its uses.

Summer bedding

Bedding plants for summer planting must be raised in early spring under glass. The skill of the operation is proved when a good uniform crop of plants is ready and hardened-off.


There is no strict definition of the somewhat loose gardening feature known as a border, and there may, on occasions, become confusion between beds and borders. However, for the sake of convenience, a border may be looked upon as a bed which is considerably longer than it is wide. True beds are normally round, oval, square or rectangular, or of some other geometric shape in which the length is not much more than, perhaps, two or three times greater than the width, although even this can not be considered to be an exact definition since a bed, say, 2 feet wide and 6-8 feet long would be better described as a bed rather than a border; longer than this it may be considered as a narrow border, sometimes described as a ‘ribbon’ border.

Two kinds of border which are occasionally seen, more often in large gardens than in small ones, are those devoted to one kind of plant and to plants of one color. These can make pleasant features, but the drawback to a border devoted to one kind of plant is that its season is a short one. Thus a border planted up entirely with, say, lupins, peonies, or delphiniums will be effective for not much more than three to four weeks. This may be tolerated in the large garden but is wasteful of space in smaller gardens. The one-color border can be planned to have a much longer life, probably throughout much of the summer, but it is not easy to design to give continuity without awkward gaps appearing as plants go out of flower.

Another kind of border is the annual border, consisting entirely of hardy and half-hardy annuals. It is not too easy to plan a successful annual border, but properly planned and looked after it can be one of the most colorful features for many weeks during the summer and early autumn. When preparing the plan, which should be done on paper first, it is essential to take into consideration the differing heights of the plants to obtain a satisfactory overall effect, and their colors to avoid color clashes, particularly as many of the more popular annuals tend to have bright colors, not all of which associate well together.

The unfortunate visual effect which can be produced by grouping orange and the brighter reds together can usually be avoided by separating these colors with patches of white-flowered plants or with grey-leaved annuals.

To prolong the flowering period as much as possible it is essential to deadhead the plants as soon as the flowers fade, otherwise, they will run to seed and cease to flower. Regular feeding with weak liquid fertilizer will also help to make the plant’s flower longer.

The range of plants which may be grown is wide, with great variation in height and color. It includes a fair number of plants grown for their colorful foliage. A pleasant effect, especially in a long, narrow border, may be obtained by using dwarf annuals only, those up to about 9 inches tall.

Another way of filling bare patches during the summer particularly is to plunge pots of plants in flower into the ground, to their rims. Such plants as dahlias and early-flowering chrysanthemums may also be used to provide extra color. The imaginative gardener will find still more variations of planting up the mixed border to provide a satisfactory and colorful feature.

All borders need extremely careful planning, and maintenance must be fairly consistent to keep the border at an optimum level of enjoyment. A complete overhaul is necessary during the dormant season, the time when the ground is dug thoroughly and fertilizer applied in preparation for the following year’s blooming season. The annual border is a great advantage here; in other kinds of borders, mixed or devoted entirely to shrubs, bulbs, or herbaceous plants, the plants remain in the ground and must be worked around with enormous care, which can be a time-consuming process.

Free Garden Catalog

Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.