Growing and Storing Dahlia Tubers
Tips for Growing Dahlias
Planting Dahlias: To plant dahlias there are a couple of options. To get a head start on the season you can pre pot up your tubers inside to get them to begin growing before planting out after all frost has passed. Each dahlia variety takes a different amount of time to “Eye up” some sprout very quickly in just a couple of weeks and others can take up to 8 weeks to show eyes, so pre potting them up in Spring gets them going much faster. To do this use small pots planting your tubers with sterile potting mix. If the pot is big enough burry the tuber just slightly under the soil. If the neck sticks up a bit that is okay too, but buried is preferred. Make sure the soil is just lightly damp but not wet. You don’t want to have the soil too wet before the plant has developed a root system or this can cause mould and rot, and possible loss of the tuber. Just lightly mist the pot every few days. Once you see the dahlia tuber pushing out green leaves then you can begin the water a bit more as it starts to develop a root system. You can move these pots into a green house as well once the weather warms up to transition out side and then eventually plant into the ground during a dry and warm period to help them settle into their new home. If the tuber neck was above the pot burry the plant a few inches below the soil when planting out.
The second method is a bit less work but dahlia blooms will come later in the season. Wait until the soil has warmed in the spring and the threat of all frost has passed, typically in late April for Vancouver Island ( Check your last frost date if you live in another part of the world).. You can plant them up until early June. Choose a location with good drainage and full sun, and prepare the soil by loosening it and mixing in some high-quality compost. Dig a hole for your tuber so that it's covered by about 4-6 inches of soil, with the eyes facing up. If you can't see the eyes yet, don't worry; they'll wake up eventually. Plant dahlias 12-16 inches apart.
Caring for Your Plants: Expect your dahlia plant to grow between 2-5 feet tall, depending on the variety. Most will need some support, such as a bamboo cane or a tomato cage. Don't water your tubers until they emerge from the soil, as over-watering can cause them to rot. Once the plants are established, water them deeply 1-2 times a week, but avoid getting the foliage wet. When the plants are about 12 inches high, cut them back by half to encourage branching and more flowers, and to prevent the stalks from becoming too top-heavy.
Picking Flowers: You don't have to pick your flowers if you prefer to enjoy them in your garden. However, if you want to share them or bring them inside, use clean, sharp snips and a bucket of fresh water. Cut the stem at least 12 inches long, just above a pair of leaves. Removing spent flowers regularly will encourage the plant to continue blooming.
Digging Dahlias: After a killing frost in the fall, the foliage and flowers will turn black. Cut the plants back to about 6 inches above the soil, and wait 1-2 weeks before digging them up so that the tubers can set. Use a digging fork to loosen the soil around the stalk, and carefully lift the clump by the stalk, taking care not to break the tubers. Gently brush away soil, and if necessary, wash off the soil without using high water pressure.
Storing Tubers: Trim the stalk to remove the green, succulent portion, and leave the tubers in a warm spot to dry for a few days. Pack the tubers into a bin or box with a loose material such as wood shavings, vermiculite, or sawdust. Store unsealed in a cool place that won't freeze. Check your tubers regularly to ensure they aren't shriveling from low humidity or rotting from high humidity, and remove any rotting tubers immediately.
Dividing Tubers: Tubers can be divided in either fall or spring, though it's usually easier in the spring. Using a sharp utility knife or pruners, separate tubers from the main stalk, making sure to keep a portion of the main stalk attached to the tuber. Discard any tubers with broken necks or without a part of the main stalk. Look for raised bumps where the tubers meet the stalk, as these are the eyes for the next season's stems. If you can't see the eyes, bring the tubers into a warmer place to help them emerge more quickly.
Remember that there are many resources available online with photos and YouTube videos. Don't worry about making mistakes; there isn't only one way to grow dahlias. Enjoy the process!