Dahlias are remarkably easy plants to grow once you get to know them. One of the best things about them is their love of life, these are some vigorous plants once they are growing in the heat of the summer. This vigour for life makes it particularly easy to multiply your plant numbers by taking cuttings.
Cuttings are exactly what they sound like, pieces of a plant cut off to grow on as a new plant. With dahlias, cuttings are taken from young new shoots that are grown on in damp compost. The cutting will product roots from the nodules where leaves grow and from tiny pieces of tuber that come with it within a matter or weeks, often within days.
You can actually take cuttings all summer from new shoots but the fastest way of rooting the cutting is by taking them directly from the plant’s tuber, the underground large energy storing roots. In spring, little buds will appear on the top of the tubers where shoots grow from.
If you plan to take cuttings from a plant, you can gently scrape back some of the soil or compost to expose the top of the tuber. Or if you’re planting the tuber in spring, leave the top slightly proud of the soil. You’ll soon see the buds burst into action and grow into new young shoots. When there is more than one shoot with at least 3 x sets of leaves and about 6 – 8cm long, you’re ready to take the cutting.
1) Find the growing points at the top of the dahlia tuber and wait for it to grow 3 x sets of leaves
2) Cut off the shoot taking a little of the woody tuber, this is where roots will quickly grow from (you can do this without the bit of tuber but it makes it easier)
3) Remove the bottom sets of leaves and reduce the remaining top set a little to reduce water loss through transpiration, don’t cut the shoot in the middle
4) Pop the lower portion of the cutting into a pot of pre-watered compost, keeping the leaves above the compost
5) Position somewhere warm and bright but not in direct sun and cover with a lid of some kind to keep moisture in – a lid isn’t entirely necessary but it can help
6) In a couple of weeks you’ll notice new leaves starting to grow, soon after this you can remove the lid and plant the rooted cutting into a larger pot to grow to a larger size before going outside.
You can repeat this process with more shoots from the same tuber, as long as it has one shoot of its own to keep growing later, it will survive and you’ll have many more plants!
I’ve got a cutting that’s taken on the kitchen window sill, it’s about 4″ tall, when should I plant it outside? Its now October in the UK
Hi Jan,
As it’s so late in the growing season, with a new cutting I would hold off planting outside now until late May next year, or whenever all risk of frost is over for you. You should find that it may start dying back naturally at some point in the next month or two while it rests over winter.
Jack