Dahlias

Dahlias are tender perennials that produce a lot of colourful flowers from mid summer right through until autumn. Frequent dead heading will ensure that they produce more and more flowers as time goes on; sometimes it feels like cutting one spent flower head off causes two to pop up in its place.

They come in nearly any colour you can think of, any height small varieties suitable for pots right up to great old 5 foot tall jobs, and a huge variety of flower shapes.

They take a little work to grow and maintain, but overall I find them quite rewarding.

Flower types

Dahlias come in a variety of flower shapes. All of them are lovely to look at, but take note: only the single flower type are of use to pollinators. While many of the more decorative flowers can be great for us to look at, they are usually inaccessible to bees and other insects.

Always plant a few single flower dahlias with the rest, just to make sure your friends have something to enjoy too.

Planting.

You can grow dahlias from dormant tubers or seeds.

from seed

Sow seeds indoor on trays in a sunny spot in early spring, and keep moist. Once the seedlings are big enough to handle you can pick them out into small individual pots and grow them on in a cold frame. Plant them in the ground where they are supposed to grow in May.

from tuber

Plant dormant tubers directly into the ground where they are to grow in late April, water in well, and cover with a layer of mulch. Any frosts at this point wont kill the tubers because the ground wont freeze.

Growing

Slugs love new dahlia shoots. Cut the bottom of a plastic bottle off and place it over any sprouting dahlias to stop slugs getting to them. You can remove the bottle during the day, but make sure to replace it at night. Once the plant has grown a bit the slugs will mostly lose interest in them in favor of more tender plants.

Dead head weekly and compost the spent flowers. The plant will keep making more.

Water generously in the summer as they are fairly thirsty plants. Feed every couple of weeks with tomato feed.

Dahlias are tender so will be killed by the first frost. At this point cut the plant back and prepare to store tubers for the winter.

Storing tubers

After the first frost cut back the foliage to about 2cm above the soil.

Use a fork to gently dig the tubers out of the ground. Be careful to put a prong through a tuber.

Gently remove the mud from around the lifted tubers and was in water. Discard any damaged or rotten tubers.

Place the tubers lifted tubers upside down on a bit of news paper in a cool dry place where air can circulate around them for a couple of weeks to dry.

Once dried place them in a breathable container of dry potting compost in a garage or shed for the winter. Keep them dry, cool, and frost free. If you don't have any dry compost to store them in you can wrap them in a sheet of newspaper instead.

Once dried place them in a breathable container of dry potting compost in a garage or shed for the winter. Keep them dry, cool, and frost free. If you don't have any dry compost to store them in you can wrap them in a sheet of newspaper instead.

Dividing plants

You can create more dahlias from dividing clumps of tubers.

Start a clump of dahlias off growing in a pot indoors and once the shoots are a few centimeters long lift the clump from the pot and divide into several smaller clumps, making sure each has roots and shoots.

Re-pot these into individual pots, and grow on until ready to plant.

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