Get a great show by growing Garden Dahlias

Garden Dahlias are one of the longest flowering plants starting in the summer months and carrying on until the autumn frosts. They provide a long season of fabulous garden colour in late summer particularly as other flowering plants begin to fade. They can be grown in both beds and, if space is limited, patio pots too.

The Garden Dahlia has an interesting history. The first tubers arrived in Europe at the end of the 18th century and were sent over to Madrid by the Spanish settlers in Mexico. Andreas Dahl, after whom the plant is named, regarded it as a vegetable rather than a garden flower. The first flowering cultivars were bred in Belgium and today there are hundreds, if not thousands of varieties.

Having been deemed to be out of fashion until relatively recently, garden dahlias are very much back in vogue! Much of this is down to the newer varieties that have been introduced and none more so than the brilliant tougher varieties in the Mystic Series.

Perhaps it’s also their vibrant zingy colours, or the infinite variety of bloom shape or maybe the ease with which they can be grown? I’m not sure which, but I do know that they are definitely in strong demand now!

Dahlia types and what to plant them with

Of course dahlias range from the dwarf almost annual bedding types to the perennial large growing showy type. The later group are divided into subsections that include ‘giant cactus’ and so called ‘decorative’ and ‘pompon’ types with magnificent flowers that make such good cut flowers! Some flower heads can be as small as 25 mm and others can be the size of dinner plates!

Garden Dahlias flower from July through to the first hard frosts of autumn and have a variety of uses. They can be used as bedding plants, borders plants and of course great cut flowers too.

Garden Dahlias can be added to a mixed border alongside herbaceous perennials such as border Phlox, Monarda, Aster and Sedum. If you have the space to dedicate to a border of just dahlias, then they can be displayed in their full glory!

Garden Dahlia Needs

Garden Dahlias will thrive in well drained loamy soil and a position that is sheltered but with plenty of sunlight.  When growing dahlias, staking will be beneficial for the taller growing types and good mulch will not go amiss in preventing weeds and conserving moisture.

They are hungry plants that need lots of feed. This can take the form of sprinkled pelleted chicken manure around each plant or perhaps a liquid feed of Miracle Gro, Maxicrop or Phostrogen each week in summer. But of course, a balanced nutrient fertiliser in early spring is needed too.  So Growmore, Vitax Q4 or blood, fish and bone meal are the preferred feeds for many growers when planting.

Stakes, string and ties are all required to support the largest growing types but the newer modern varieties tend not to need support. Be on the look out for slugs and snails when you first plant then out. Control these by scattering some Growing Success Advanced Slug pellets around the plants until they get well established. Earwigs like to feast on the flower petals at night. An old remedy of putting a small flower pot filled with wood wool upside down on canes among your plants entices the earwigs to hide in there during the day. Regularly shake them out and dispose of them.

What to do in winter

Most dahlias will be blackened by the first frost of autumn and all top growth will collapse. Fortunately they create food storage tubers underground and it is from these that they shoot again in spring. Traditionally these tubers are dug up, dried off and stored in frost free places. However, with warmer winters and with hardier new varieties of garden dahlias [Mystic and Bishop types in particular] roots can often be left in a sheltered garden. Deep planting and the application of thick insulating organic mulch to keep the frost out can make all the difference!

If dahlias are grown in pots then those pots can easily be moved inside when the top growth dies down in winter. The roots are especially at risk from frost damage when in pots.

Mystic and Bishop Series of Garden Dahlias

Mystic dahlias are the dark leaf hardier garden dahlias that we grow. However we do also grow a few of the other hardier varieties such as the well known ‘Bishop ‘ varieties. Neither a Bishop or a Mystic, we find that ‘Moonfire’ is a great single flowered bicolour. All of these are single flowers which is good news for bees! Dahlias are very good garden plants to encourage bees and pollinating insects.

The Mystic Series of garden dahlias have been bred by a Brit who has moved to New Zealand! Dr Keith Hammett has concentrated on breeding prolific blooming single flowered dahlias with very dark foliage. The dark leaves are a great contrast to the bright and cheerful blooms!

These single flowered Mystic Dahlias are especially attractive to bumblebees. In fact that is true of all the single flowered types of garden dahlias.

Do you have a favourite garden dahlia variety?

What other plants do you think compliment the bright colours of dahlias?

I’ve written more about these fabulous plants here.