Dahlias are available in countless cultivated forms, which are now native to our gardens as descendants of Mexican immigrants. However, the heat-loving tuber plant is not hardy in our area and therefore has to be replanted every year after overwintering.
When and how should you plant dahlias?
Dahlia tubers can be planted outdoors from late April to mid-May after the ground is frost-free. Dig a planting hole, add a drainage layer of sand and insert the tuber 5 centimeters deep. Make sure there is a planting distance of 50 to 100 centimeters, depending on the variety.
When do I plant dahlias outdoors?
It is usually advisable to plant dahlias directly outdoors from mid-May - i.e. after the Ice Saints. In fact, the tubers, which are actually sensitive to frost, can be planted in the bed earlier if the weather is right. As long as the weather is mild and the ground is frost-free, you can start spading as early as the end of April. If there is a threat of late frosts – always keep an eye on the weather forecast! – simply cover the planting site with garden fleece, straw and/or pine branches.
Should you water dahlia tubers before planting?
It is often advisable to water dahlia tubers thoroughly before planting so that the bulbs that have dried out over the winter soak up water and wake up from hibernation more quickly. This method can actually get the dahlias to sprout earlier, but it also carries the risk of rot. Especially in rather cool and rainy springs, the tuber, which is soaked with water, is in danger of rotting in the ground. That's why you can safely avoid watering and prefer the tuber to the windowsill instead.
How do you plant dahlia tubers correctly?
When planting, it is best to proceed as follows:
- check overwintered tubers for rotten spots etc.
- dividing large tubers
- Dig planting hole
- Planting depth approx. 5 centimeters
- There should only be about 2 to 3 centimeters of soil above the shoot buds
- Planting distance 50 to 100 centimeters depending on the variety
- Apply coarse-grained sand as a drainage layer to the bottom of the planting hole
- pour heavily
Plant the tubers so that last year's shoot tips still stick out of the soil. You can also plant dahlias deeper - and thus protect them better from frost - but they will then sprout later. For tall varieties, also attach a support rod to tie the inflorescences to later.
Which soil do dahlias need?
Dahlias grow almost anywhere, but love humus-rich, well-drained soil. Therefore, when planting the tubers, you should add plenty of compost and well-rotted organic fertilizer - such as stable manure - to the planting hole or mix the excavated material with it. Heavy, clayey soils definitely need loosening with sand and compost as well as a thick drainage layer of coarse sand. How to prevent waterlogging.
Tip
When can you prefer dahlias?
Instead of watering the tubers, you can also push them forward and encourage the perennial to sprout and bloom more quickly. For earlier flowering, you can grow the tubers in large pots on your windowsill at home from March onwards. The pot should be kept bright and warm, and regular watering is also important - just don't let it become waterlogged. After the Ice Saints, plant the dahlia outdoors.
