How to Grow Beautiful Dahlias

Is there any flower as big and beautiful as a Dinnerplate Dahlia?  I’m not sure, but I can’t resist growing one to enjoy every summer.  They also make great cut flower that last well indoors.  Dahlias may look delicate, but they are actually surprisingly easy to grow provided you follow these tips.

grow dahlias in Calgary

Display of packaged Dahlias.

Step 1.  Purchase your Dahlia in early spring.  They are usually available in late February, so visit your local garden centre and choose a dahlia that’s attractive to you.  Make sure you look at the tag: some Dahlias can be 4 to 6 feet tall, so you’ll want to make sure you have space.

Grow your own Dahlia

Two varieties of Dahlias “Ice Cube” and “Babylon Purple”. They will both be about 4 feet tall.

Step 2.  Before purchasing the Dahlia, look at it in the plastic bag.  You want to make sure that the bulb, which looks like a cluster of bulbs is firm and not soft and wrinkly.  Check to make sure there isn’t mold or rotten black spots.

bulbs, summer flowers

This is a healthy Dahlia tuber with no signs of mushiness or rot. See how firm the bulbs are?

Step 3: Choose a 6 inch plastic pot, and fill it half full of new, good quality potting soil.  Then take the dahlia bulb out of the bag.  The stem end should be up, and the little potato like bulbs will dangle down.  Carefully place the dahlia into the container, and spread apart the little bulbs as much as possible.  The stem end should be about 1 inch below the level of the soil.

Dahlia tubers

The top of the Dahlia bulb has an old stem. The bottom has the potato like tubers hanging down.

Step 3:  Carefully fill up all the spaces in the pot with potting soil, gently tamping it down with your fingers.

Placing the bulb into the pot when it's 1/4-3/4 full.

Placing the bulb into the pot when it’s 1/4-3/4 full.

Step 4: Water the pot in the kitchen sink, making sure the soil is moistened well.

Step 5: Keep the Dahlia in a warm spot until it sprouts.  (On top of your fridge is a great place)

Step 6: Once they are sprouted, they need lots of light, so place in a bright window, and rotate daily for even growth.

Step 7: After the risk of frost has passed, and the nights are staying warm, it is time to move your Dahlia outside.  If possible, transplant the Dahlia to a large ceramic pot 1-4 weeks before you move it outside.  Follow the transplanting instructions in Step 8.

Step 8.  To transplant your Dahlia: Choose a ceramic pot  (or plastic if that’s more budget friendly) that is at least 12 inches by 14 inches.  (Dahlias are large and heavy)  Fill the pot up to the three quarter mark and mix in some organic flower fertilizer.  Flip the dahlia’s small pot over, support the stem, and spank it on the bottom a few times with your hand until you can pull the pot off.  Place the dahlia and root ball in the pot, and see if the level of the root ball is within 1 inch of the top.  If not, add or remove soil beneath it as necessary.  Once it is within 1 inch of the top, fill the remaining spaces with good potting soil.  You may also plant smaller annuals such as pansies or lobelia around the dahlia for more colour. Water well so the container is moist.

Step 9: Harden off your Dahlia.  Try to put it outside for an hour in a shady spot the first warm day, then gradually increase the time outdoors as well as the sun until the Dahlia is used to being in full sun all day and night.  (Mine is on an East facing patio near a dark green wall)

Step 10: Enjoy!  Dahlias take awhile to grow to maturity and flower, so be patient.  It helps to keep them well-watered, and if you find your Dahlia is wilting during the hot days, you can stick a funnel into the soil and keep that filled with water for an extra boost.  Once the Dahlia begins to flower, feel free to cut blooms and bring them inside to enjoy.

Dahlia flower, flowers in Calgary

A mature Dahlia. Look how gorgeous they are!

Step 11: Once fall comes, expect to find your Dahlia brown and mushy after the first hard frost.  Once that happens, you can carefully dig up the bulb and store it in a paper bag in a cool dark area.  When February comes, begin the process all over again.

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