Growing Dahlias

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.

Dahlia with Bee

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.

Delightful Dahlias

Get ready for the annual tuber and plant sale by The Monterey Bay Dahlia Society, next Saturday, April 6th, at the Deer Park Shopping Center, in Aptos.

The sale will open at 9:00 a.m., when there likely will be a line of eager dahlia growers looking for the latest hybrid introductions, or particular favorites, or specific colors to complete a landscaping design.

Or all of the above!

The dahlia, a native of Mexico, grows quite well in the Monterey Bay area’s moderate climate.

There are many varieties of dahlias, so selection of plants for your garden is the first task. A good and simple rule of thumb is to select varieties that please your eyes. Other approaches include selecting plants that have won prizes or that have blossoms of the color, form or size that you prefer.

Fortunately, there are excellent plant selection resources on the website of the American Dahlia Society <>; click on the link for “Dahlia Resources.” To view photos of dahlia blossoms, conduct a Google search for “dahlia plants” and click on “Images”

Tubers are specialized structures designed to store nutrients during a dormant season. Dahlias are stem tubers, which differ from root tubers, like potatoes. A stem tuber has one or more buds on the end that was attached to the old plant. These buds, called “eyes” are the plant’s growing points, so examine actual tubers to spot an “eye.” Even experienced growers can have difficulty recognizing an eye, but a tuber lacking an eye will not produce new growth, so look closely.

The ADS website also provides information on cultivating dahlias. The basic (and easy) method is to select a spot that enjoys at least six hours of direct sunlight every day, and good drainage. The time to plant is between “right now” and about mid-June. The top of the tuber should four-to-six inches below the surface (larger tubers are planted deeper) with the “eye” facing upwards.

Taller dahlias should be staked to avoid flopping. Install a stake near the tuber at planting time; pushing a stake into the soil later risks damaging the tuber.

If you prefer not decorating your new dahlia bed with bare stakes, install a short piece of plastic pipe next to the tuber, with the top just above soil level. Then, when the plant threatens to flop, insert a thin stake into the plastic pipe and tie the dahlia to the stake.

Snails enjoy snacking on dahlias, so as soon as new growth appears, apply non-toxic snail bait, such as Sluggo or Escargo. Gophers also find the tubers tasty, so plan to monitor for evidence of gopher activity, and have traps ready.

Enjoy your garden!


2013 Dahlia Sale