Dahlia Growing Info
Dahlias are beautiful flowers that come in a wide range of colors and sizes. They are relatively easy to grow and make a great addition to any garden or outdoor space. Here are some tips on how to grow dahlias:
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Planting: Dahlias prefer well-drained soil and full sun, so choose a location that receives at least 6-8 hours of direct sunlight per day. Plant the tubers in the spring, after the danger of frost has passed (generally April-June). Dig a hole about 6-8 inches deep and place the tuber with the "eyes" or growth points facing up and the tuber laying horizontally on the soil. The eyes can be difficult to find but are on the crown/neck of the tuber rather than the body/round part of the tuber. If your tuber is waking up out of dormancy you may see an actual sprout coming out of the eye - make sure it is facing the sky. Cover with soil and water thoroughly. Space out tubers 12-24 inches apart to give them enough room to grow. You can also plant dahlias in containers - a 5 gallon bucket works well!
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Watering: After planting, do not water until you see green pushing up out of the soil to avoid tuber rot. Be patient at this time as it may take weeks before you see any growth. After you see green shoots above the soil, Dahlias require regular watering, especially during hot and dry weather. Water deeply once or twice a week, depending on rainfall and soil moisture but avoid overwatering. Water as close to the soil as possible rather than on the plant.
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Fertilizing: Fertilizing is completely dependent on your soil - at Lunaria Flower Farm we do not add any additional amendments outside of organic compost but it's best to investigate your soil constitution to determine whether or not to fertilize.
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Supporting: Many dahlia varieties grow tall and may require support to prevent them from toppling over. Use stakes or cages to support the plants as they grow.
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Pinching: When the plant reaches 12 inches tall, take a pair of clippers and cut the central vertical growth right above the 2nd full leaf pair at the node. While it may seem counterintuitive to cut your plant in half when it is just getting going, this will actually make for a much stronger and more productive plant. By cutting back the growth early, the plant will become stronger and produce more lateral shoots.
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Pest and disease issues: Look out for slugs in early growth and powdery mildew on leaves. Once the plant reaches about 2-3 feet tall you can remove the leaves on the bottom 12 inches of the plant to increase air flow.
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Deadheading: To encourage continuous blooming, remove spent flowers regularly. Cut the stem just above a leaf node to promote new growth.
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Overwintering: Dahlias enter a dormancy period in the winter and need to be dug up and stored indoors. Wait until the first frost has killed the foliage, then carefully dig up the tubers and remove any soil. Allow them to dry in a warm, dry location for a few days before storing in a cool, dark place for the winter packed with peat moss or saw dust. You can divide for more plants in the spring and replant your tubers for years to come.
More resources:
1. SF Dahlia Society Growing Guide in the Bay Area
2. Santa Cruz Dahlias Videos
There is a lot of information about growing dahlias but make sure to adjust specifically for your growing region and soil type!