How to plant and grow dahlia tubers
Overwintering your dahlia tubers:
• After the first frosts have killed the foliage, cut the stem to about 15-20 cm, then lift the tubers.
• Knock off any soil and carefully scrape the soil out from between tubers.
• Do not use water to clean your tubers
• Leave them to dry for a couple of weeks, hanging upside down from the stalk.
• Fill a storage box with dry sand or potting compost and bury them in in.
• Store them in a cool, dry, frost-free place – a garden shed or cellar is perfect.
Dahlias are a reliable cut flower which can be grown with relative ease in your garden. They will flower from June right up until the first frosts. There are hundreds or forms, colours and growing habits to choose from.
Dahlias love a sunny site, with moisture retentive soil and benefit from being sheltered from wind. They can be staked or supported if your site is exposed.
Planting up in pots.
When they arrive your tubers will look like a brown mass of tubers attached to last years central stem. Dahlias will grow a bit like potatoes - new shoots will sprout from 'eyes' or nodes on the tubers.
• Choose a large pot (3-5 litre about 30 round) and lay the bottom with crocks for drainage.
• Add multipurpose compost and a slow release pot fertiliser.
• Lay the tuber on the soil and cover with compost adding more slow release fertiliser to this layer.
• Plant them as deep as you would in the ground, so a good few inches.
• Water well and keep in a frost free sheltered place - greenhouse or shed. When they start to sprout bring them outside after the frosts.
Planting in the ground.
• Dig out a hole 30cm deep and add compost or well rotted manure. Add grit if your site is clay based.
• Knock in a stake before placing lay your tuber on the top, water well. Then back fill the hole.
• Feed with liquid feed once a fortnight and water during any dry periods.
• Allow only 5 shoots to grow from the tuber, this encourages a bushy productive plant.
• Pinch out the tips of main shoots to encourage more side shooting stems for more flowers.
• Cut flowers and deadhead regularly and more will follow.
• Re-cut hollow stems underwater to prevent an airlock in the stems. Trapped air will travel up the stem and cause the dahlia to prematurely wilt.
Pests to look out for.
• Protect your dahlias from slugs - especially emerging shoots
• Earwigs will eat grown flowers and leaves. So you could either shake the dahlias and pick them off.
• Or an organic tip is to create a 'nest' for earwigs to escape to during the heat of the day. - fill upturned plastic pots with straw and balance on canes around your dahlia bed. Earwigs crawl up the canes and can be collected in the afternoon.