If you need a reliable border plant to provide a glorious burst of colour, you simply cannot go wrong with dahlias. Offering a dazzling variety of shapes and sizes, there is something to suit any space, and they work in pots too, which gives you the flexibility to move them around when you fancy a change!
Planting dahlias under protection in March-April (before hardening off and planting out in late May) will ensure large, healthy plants with lots of flowering potential – and it means you’ll be able to take cuttings too, so you can create even more plants for your display!
We’re often asked about which way up the tubers should be planted, and how to plant them, so we’ve put together the guide below.
As with any project you’ll need ‘ingredients’…
- Your pot or container
- And of course your dahlia tuber of choice!
What you’re dealing with…
The tubers themselves are strange, oblong shapes and often it’s difficult to determine which way up they should be and, therefore, exactly what to do with them!
In order to determine which way is ‘up’, the trick is to look for the cut off stems of previous growth. The image on the left below shows the remnants of last year fairly obviously, while in the middle image it is shorter and less obvious.
When it comes to planting, don’t plant the tubers in a bunch pointing downwards, you should be aiming for a ‘spider’ shape as shown in the image on the right.
Planting in Pots
Place crocks in the bottom of your pot to improve drainage and fill it with compost, leaving enough room to place your ‘spider’ of dahlia tubers on top – as shown in the images below.
Then, while gently supporting the crown (last year’s cut off stem) with your finger, carefully fill around your tuber with a layer of compost, making sure that you leave the top of the top of the tuber showing, as demonstrated below.
Ensure that the compost stays moist, and place your pots in a light, frost-free position – and within a few weeks, you should expect new shoots to appear.
Planting Out and Care
Once the risk of frost has passed, you can harden off your dahlias and plant them outside, where they’ll do best in a sunny site. They are hungry plants too, so make sure you prepare your soil by digging it over and incorporating lots of organic matter.
Leave 15-45cm between plants when planting, depending on the variety you are growing, and water them well. Then once the plants are 30-50cm tall, cut out the tips of the main stems to encourage side shoots for more blooms. Water your plants generously during dry weather and, for an extra boost, add liquid fertilizer every two weeks.
Although in some areas dahlia tubers can survive the winter outside, it’s best to ensure they’ll be available in future years by lifting and storing them in Autumn, as soon as it starts to get frosty – this is particularly important if you are gardening in heavy soil.
Visit us to check out our range of lovely dahlia tubers, plus we have all the pots, planters and compost you’ll need to create some dahlia-dazzle in your garden!