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Mother’s Day – Dahlias for garden and vase

Mother’s Day – Dahlias for garden and vase

Fri 25 March

Dahlias spent several decades in the doldrums, being very unfashionable. But they are back in the spotlight again and no flower is better for cheering us all up and filling our lives with colour, whether in the garden or in the home. Dahlias are easy to grow and bloom all summer, right into late autumn. The simplest way to start is with tubers but you can also grow them from seed. They are as easy to grow as marigolds and if you have grown other plants from seed you will succeed with dahlias too.

Starting from seed

Dahlia fanciers will dispute whether growing from seed produces good dahlias and the problem is that they are unlikely to produce large, double flowers on tall plants – the kinds you see at flower shows. But they will produce perfectly acceptable garden plants with single flowers. Personally I would not bother with seeds of tall, double kinds no matter how good the photo looks. But it is a good way to grow the dwarf, double kinds and dahlias are easy to grow from seed. Because the seedlings grow so fast I would delay sowing till early April. The seeds are large and flat and germinate fast. Avoid overwatering and grow them in good light. Last year I  sowed some seeds of tall, single kinds I had collected the year before. I had forgotten I had them and did not sow them until June but the plants all flowered in September and flowered until the frost. I marked the best and have saved the tubers.

Growing from tubers

Tubers are the only way to grow the big, bold doubles. Unlike from seed, you can be sure of exactly what you will get. As mentioned above, all dahlias make tubers and even if you grow some from seed they will make tubers that you can keep and grow the next year.

There are two ways to treat tubers you buy. The simplest is to plant them in the border where they are to grow. Dahlias are not hardy so it is best to wait till April to plant so that shoots do not emerge until May. A tuber consists of a stem with fleshy tuberous roots below. These thick roots do not sprout – the shoots come from the base of the old stem so any tubers that get broken off will not grow – they are just to store food for the plant (oddly, if you do plant the broken off tuberous roots they will make roots but will never produce shoots).

A better way to start Dahlias is to put them into pots. Plant them so the top of the fleshy tubers is at compost level. Keep them warm and moist, in light, and you will soon see green or purple shoots. If several shoots appear you can cut the tuber in half, slicing vertically through the old stem. The two halves can then be re-potted to grow on: two for one. If you are very adventurous you can remove the shoots when they have grown a bit bigger and root them as cuttings, but let’s stick to basics.

Dahlias then need a sunny spot outside. Do not plant them out until all danger of frost is over. Dahlias like rich soil and lots of water so mix in plenty of well-rotted manure or garden compost and keep the plants watered in dry weather through summer.

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