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Ground Preparation

Dahlias > Dahlia Care


Once you have gone to the trouble of designing your flower beds and selecting your lovely flowers/tubers, you will need to give them the best chance of growing into beautiful specimens.

Firstly, make sure that you have properly prepared the ground where you intend to plant your flowers. It goes without saying that the soil should be cleared of weeds and debris. It also helps to dig the ground over and mix some good quality compost in to increase the nutrient levels in the soil. Dahlias do best with a rich, moist soil of pH 6.5 which should also be well drained.

Adding some well rotted manure and wood ashes to the soil before planting is a very effective means of fertilising the soil and helps to keep the pH alkaline as opposed to acidic which will not suit the growth of dahlias. Since these flowers are very showy, it follows that they will require a steady source of nutrients as they grow and bloom. The addition of bone meal to the top soil at an appropriate dosage is essential for good results and a long growing season.

Bear in mind that some dahlias can become very tall and will require a support to protect them from wind damage as well as to support their weight as they grow to keep them straight. Use a mulch to keep weeds at bay.

Take a really good look at your space at various times of the day. Make a note of where the sunny parts lie, where the more damp or wet areas are and also pay attention to which bits are subject to shade for most of the time. Don’t be discouraged if your particular garden isn’t in the most desirable aspect. Even in the most awkward areas, there will be a dahlia that will be suitable and can flourish.

Although dahlias will grow well in any soil, they thrive best in rich soil with good drainage, and one way to achieve this is to raise the level of the soil by incorporating as much humus as possible.  Even though dahlias benefit from copious amounts of water, they dislike standing water, and good drainage should be ensured.  Dahlia roots will grow down to considerable depths in searching for water, and it is helpful if the ground is well dug and a dressing of a basal fertiliser incorporated into the soil at least two or three weeks before planting.  An organic fertiliser is best such as bone meal, or fish blood and bone, at the rate of three or four ounces to the square yard ( two good handfuls) is adequate.

Planting out should not be attempted until all risk of frost is over.  This will be late May in the south of the country, but in the north, mid June might be best.

Plants should be well hardened off before planting, although tubers can be planted in mid April, but precautions must be taken to protect emerging shoots from frost. by earthing up or covering with newspaper overnight.  Some growers start the tubers in a greenhouse or cold frame, and when the new growth is visible, the tubers are divided into pieces, each with a growing shoot, and then planted out in late May.

It is advisable to mark out the positions for each dahlia using a cane, the spacing between plants will be determined by the types involved.  Large and giant types will require three feet apart while small and miniature types will be happily accommodated two feet apart.  Dwarf bedding types can be grown as close as one foot when they will require little staking.

As every gardener knows, it is also essential to understand what soil type you have in your garden. Soil testing kits are widely available in garden centres. They can quickly tell you whether your soil is acidic or alkaline and this will have an impact on what kinds of plants can be planted and thrive in those conditions.

Think about how you’d like your garden to look and remember that dahlias can grow to a variety of heights so you can be as creative as you like to guarantee a real impact.

There are nine distinct types of dahlia and the flowers can range in style and size. It is therefore very important to check the grower’s labels when buying the plants as they will give all the essential information on them such as expected height, whether it is suitable for a sunny or shaded spot as well as the shape of flower that you should expect to see when it is in bloom. So, plan carefully to make sure that the specimen that you choose will work in the place that you intend to plant it.

When planting, do not forget to allow adequate space. The tallest varieties should be spaced between 60-75cm apart. These can be used as backdrops to the rest of the garden and when planted in rows, they look impressive as well as being accessible for cutting.

Medium sized dahlias should be planted about 50-60 cm apart. These are good for breaking up bedding plants and adding texture to the garden. The smaller types should be 30-40 cm apart and these are always useful in any garden, especially if you want to grow them to use in a bouquet as cut flowers.

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