What to Do With Dahlias in July for Even More Spectacular Cut Flowers hat Last Through Fall
Our dahlias are finally in flower, but the hard work isn't over if you want to keep them blooming until fall
July is here and with it, the first dahlia blooms. But, this doesn't mean it's time to sit back and enjoy the showy flowers, there are a few maintenance tasks to keep on top of this month to prolong your dahlia display.
Growing dahlias is straightforward, so long as you meet their basic needs. In summer, this includes deep watering, fertilizing, and regular pruning to encourage even more blooms. It's also important to give the tallest stems some support to stop them flopping over and snapping.
You can also start cutting your stems for vase arrangements this month (which is a key way to keep dahlias blooming for longer), so make sure to have sharp gardening snips to hand (like these from Amazon). Here, we talk through exactly what to do with dahlias in July.
1. Fertilize Weekly
Now that your dahlias are blooming, they're using up a lot of energy and the nutrients in their soil are depleting quickly. That's why July is an important month to establish a regular dahlia fertilizing regime.
'You can feed your dahlias as often as weekly when they start flowering,' says Rachel Bull, Homes & Gardens' Head of Gardens. 'A liquid high-potash feed is my go-to, as it encourages profuse, vibrant blooms,' she adds.
You should look for a feed with a high potassium plant fertilizer numbers, such as this specific dahlia fertilizer on Amazon. Alternatively, you can actually use a tomato feed (like this Espoma one from Walmart) on dahlias, as it's high in potassium.
Complement this with a layer of organic mulch or compost for a consistent supply of nutrients and to lock in moisture during hot summer days.
Apply up until early fall to boost essential plant nutrients and encourage a long blooming period.
magazine, sparking a love of container gardening and wild planting. After more than a decade writing for and editing a range of consumer, business and special interest titles, Rachel became editor of floral art magazine The Flower Arranger. She then trained and worked professionally as a floral designer and stylist for six years, and has created floral installations at iconic venues. She joined the Homes & Gardens team in 2023, where she heads up the Gardens section, and presents the weekly gardening and floristry social series Petals & Roots.
2. Stake Tall Stems
Dahlias are one of the plants to stake, especially for the biggest varieties (such as this Noordwijks Glorie Dinnerplate Dahlia from Amazon).
Failing to put a support in place can result in top-heavy blooms flopping over and even snapping in the wind.
There are lots of different solutions for staking dahlias, from creating a natural support from tree cuttings to using bamboo stakes (like this pack from Walmart).
Typically, a plant support of 4-6ft in height is ideal for dahlias, but it of course depends on your specific variety's ultimate height.
You should use soft ties or jute twine (like this from Amazon) to attach stems to the stake, so it doesn't cut into the flower stems. You can also use the figure-of-eight tie to prevent the stems rubbing against the stake.
3. Keep Deadheading
Now that dahlias are blooming, it's time to stay on top of deadheading. Removing spent flowers will redirect the plant's energy into putting out more blooms.
'Harvesting cut dahlia stems as part of a cutting garden is one of the best ways to prolong your dahlia's display,' Rachel adds.
Whether you're cutting flowering stems or deadheading dahlias, always use sharp and clean gardening snips (like these Fiskars ones from Amazon) and cut down the stem to a set of leaves.
This ensures the plant will put out new growth from the nodes and provide even more blooms until early fall.
Shop Dahlia Essentials
This liquid dahlia feed is packed with nutrients to support blooming and encourage a longer display. Dilute with water to apply.
These bypass pruning shears have a steel blade to make clean cuts. They're perfect for cutting dahlia stems.
These 4ft bamboo stakes are ideal for supporting medium-height dahlia varieties. You get 25 in this pack.
If you want an even more magnificent dahlia display this year and they haven't yet started blooming, now is the time to pinch out dahlias and encourage bushier growth. You can also strengthen your display by incorporating dahlia companion plants nearby.
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