Common name: Dahlia, Georgina

Botanical name: The botanical name dahlia was given in honour of the Swedish botanist Anders Dahl. The plant also had been named Georgina in honour of the German botanist Johann Georgi. The plant is native to Central America, from where it was imported to Spain in 1525, but is thought to have died out and reintroduced in 1787. It was widely popular, especially with nobility; reputed to be a particular favourite with French Queen Marie Antoinette, and so it spread quickly throughout the gardens of Europe.

Family: Dahlia is part of the daisy family, the Compositae, and within that large group, the Asteraceae. It has all of the different shapes of daisies. The stems of some large species were used as water pipes by the Aztec people and known as acoctili. Dahlia was declared the national flower of Mexico in 1963.

Garden use

Superb in a flower border, dahlia is very popular and widely available. It is a major contributor colour in late summer and into autumn. Dahlia tubers are available in a wide range of types but there are two main groups.

The most common group is the small-sized bedding dahlia, grown from seeds sown in spring and planted out after frost has passed in late May. The second group, also widely grown, is the border dahlia, bigger plants that are grown from the tubers, carried over from year to year.

All kinds produce tubers, of course, but the bedding kinds have small, poorly developed tubers and they do not usually re-establish all that well the following year. So the bedding kinds are raised from seeds each year, which is also a lot easier than trying to over-winter lots of tubers.

Bedding dahlias have quite large seeds and they germinate readily. It is possible to buy plants but growing from seed is cheaper and more fun.

The border dahlias are in the shops now too, usually as polythene-bagged tubers, sometimes only one plant, sometimes three to a pack. A wide choice of colours, sizes and flower shapes are available, especially if the choice of several outlets is taken into account.

Most of these varieties are tall growing, reaching about waist-height or more, and they are ideal for country gardens because of their size and colour impact. The range of colours is very wide, from white to deep purple, yellow, orange, red and pink — every colour except blue.

Then there is a range of flower shapes. These shapes have been bred over many years to give singles, doubles, peony-shape, cactus-shape, semi-cactus, pompom, collarette and several others.

Although the exact classification is of interest primarily to enthusiasts, it is worth being aware that different shapes exist. Everybody has their own favourite and the most common would be the decorative and semi-cactus types.

Dahlia is very popular and is widely available

It is probably a good idea to stick to one or two flower shapes. The range is so large that it is easy to choose complementary colours — unless you deliberately set out to have a mixed lot. If a colour does not really succeed one year, try a different kind the following year, and if you find one that sets off the garden well in late summer, increase numbers, either by carefully dividing the tubers, making sure each groups of tubers has one or more stems, or by taking cuttings of the shoots once they are about 20cm long.

Growing dahlias

Dahlias are not hardy — the stems and the tubers can be damaged by frost. If buried deep enough or covered with a layer of sand or old ashes, the tubers will survive winter undamaged in most parts of the country, but this method is not completely reliable except in the milder coastal areas.

Other dangers to the tubers are posed by damp soil and the activities of slugs and snails, which graze down the emerging young shoots. As a result, it may be safer to lift the tubers in late October or November when frost hits the foliage, but they can dry out and die, or rot in store, if conditions are too dry or too humid. Hard frost can occasionally damage tubers in store too.

Buy the tubers in the coming month and pot them in large pots of peat/soil mixture, lightly watered and stood in a greenhouse or shed with some light.

Be careful about watering until growth is active. Buy enough tubers to make one or two clumps of three plants to gain some impact or more, if desired.

Assess the locations that might be used for these dahlias when planted out in late May. Ideal positions would be midway in a mixed border, in gaps between shrubs or where early-flowering plants might have faded. Dig in lots of rich feeding at planting and feed well. Staking is usually a wise precaution.

Border dahlias are very vigorous as they are what is known as octoploid plants with eight sets of chromosomes. The resulting vigour and soft growth makes them prone to being blown


Kitchen garden

Tomato seeds to grow as plants in an unheated greenhouse can be sown now. Seeds sown early would need some frost protection. Tomato seeds germinate very quickly in a warm place indoors and can be raised to planting size on a windowsill. Only a few plants are usually needed although more may be raised and given away, especially if too many seedlings come up.

Seeds of sweet pepper, chili pepper, tomatillo, aubergine and Cape gooseberry or physalis, all related, can be sown now too.

Try a new variety each year in addition to tried and trusted favourites. Planting out in April will see the plants growing away strongly as the growing season warms up. Prepare the soil for planting by adding some well-rotted manure to enrich the ground. Seeds of sweet pepper, chili pepper, tomatillo, aubergine and Cape gooseberry or physalis, all related, can be sown now too.

This week’s reminders

Fruit, vegetables and herbs

Flower buds on fruit trees and bushes are early this spring because of a relatively mild winter. Pruning of apple and pear trees

should be completed. Plant garlic and shallots sets, if the ground is dry enough. Sow seeds of early varieties of cabbage, cauliflower, carrots and lettuce.


Mowing now and again in three or four weeks will leave the lawn area looking neat and tidy before growth starts. Apply lawn moss killer if there is heavy moss growth. If new areas of lawn are to be sown, the ground should be cultivated, if possible, in good conditions.

Trees, shrubs and roses

Planting of deciduous kinds should be completed this month, evergreens soon after. Bedding roses and repeat-flowering climbers should be pruned in the next two weeks, if not already done. Rose bushes can be planted at any time. Move young shrubs that are badly positioned.

Greenhouse and house plants

Greenhouse peach trees should already have the first flowers gently pollinated with a small soft paintbrush or by vigorously tapping on the support wires. Watch for pests and water all potted plants. An early liquid feed should be given now to encourage new growth.


Perennial flowers are showing good growth in many cases and lifting and dividing of herbaceous flowers can resume. This is the best time to move perennial flowers in gardens on heavy soil.

Begonia and gloxinia tubers can be started in a greenhouse, or on a windowsill indoors.

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