Dahlias are among the easier blossoming plants to cultivate in the garden. As natives of Mexico, they thrive in the Monterey Bay area climate and bring drought-tolerance as well.
As mentioned in today’s article about the upcoming sale of the Monterey Bay Dahlia Society, dahlias are available in many different blossom forms and colors and can be a fine addition to the garden.
This column offers basic practices for growing dahlias after you have selected tubers at the Society’s sale.
The first consideration is to select a location will full exposure to the sun and good drainage. Dahlias, like most flowering plants, grow best with six hours of sun each day, and in well-drained soil. Sandy loam is fine, but clay soil will require substantial amendment with organic material.
Dahlias can be planted any time between the last day of frost (which is not a concern in this area) and as late as mid-June. The local tuber sale is scheduled around the time when last season’s tubers are ready to be dug and divided, so the day of the sale represents a good beginning for the local planting season. If you are not ready to plant, store your new tubers temporarily in a cool, shady environment.
Most dahlias will need staking, so it’s a good practice to position a sturdy stake for each tuber, and to install the stake at the same time that you plant the tune. Inserting a stake later runs the risk of stabbing the tuber.
If you don’t want bare stakes in the garden while the plant develops, you could install a short piece of plastic pipe with the top at ground level next to the tuber, then, when the plant grows to need staking, insert a thin stake (bamboo?) in the plastic pipe and tie the plant to the stake.
Plant the tuber several inches deep, with the “eye” (the growing point) facing up. Some tubers might lack such an eye, and will not sprout, but well-selected tubers will have viable growing points. The eye can be difficult to confirm, so selection can require some experience in identifying tubers that are ready to grow.
Separate the tubers from each other by about two feet.
Protect the sprouting plants from snails and slugs. A good practice is to visit your plants in the night (with a flashlight) or in the early morning to remove any crawling pests that have discovered them. Regular applications of an organic snail control, e.g., Sluggo, also works.
Control flying pests with insecticidal soap or other organic pesticides.
Generally, soil with ample organic content will provide sufficient nutrients for dahlias. If your soil seems “lean,” regular applications of high-nitrogen, organic fertilizer would be helpful.
As each plant grows, tie it to a stake to ensure that it remains upright. The first tie should hold the main stalk loosely to the stake; later ties could connect branches to the stake.
Each branch generally will produce three buds. To produce large blossoms, many gardeners remove two of these buds when they appear. This disbudding process allows the plant to direct nutrients to the remaining bud, with positive effect. If you have several dahlias growing in the garden, you will still have lots o blooms.
At the end of the season, the top growth dies back, and the plant produces several new tubers. The gardener can remove the top growth, and can either dig and replant the tubers or leave them in the ground. In the Monterey Bay area’s moderate climate, dahlias grow quite well when simply left in the ground. After two or three years, they will become crowded and will benefit from dividing.
Enjoy your dahlias! They are wonderful additions to the garden.