Dahlia tubers getting started in aluminum trays.
Did you buy dahlias, bleeding heart, lilies, or another type of perennial packed in a plastic bag? I can’t stress this enough: Get it out of that bag as soon as possible! Buying in a bag is the equivalent of a neighbour digging up a perennial plant from her garden and, not having a pot, sticking in a plastic bag for you to lug home. It works fine, but it’s a temporary measure. It’s a cost efficient way for plant sellers to save on soil and pots when they sell you a plant. Saves on transport costs too. However, it’s not a great way to ensure the survival of the plant when you get home. You may think to yourself, “I’ll get around to that later”, then forget about it. There’s nothing sadder than opening a bagged dahlia and seeing the shoots, white and gnarled where they have tried to grow inside the bag. I’ve done this many times, and, weeks later, found half-dead (or fully dead) plants waiting for me in the bag, staring at me accusingly….why???
It makes sense for dahlia growers to sell in bags, as tubers are dug in the fall and stored indoors for the winter in our climate. The bare tubers easily manage over the winter, but the closer to the growing season, the sooner they need to be back in their natural habitat: soil. And that means, roots down, sprouts up.
Just enough soil to partly cover dahlias is better than sitting in a bag.
There is a handy trick for planting procrastinators. It’s a half-step that gives you more time while you are looking for soil, plant pot or space in the garden. I learned this from Sarah Nixon, Parkdale’s flower farmer, who had aluminum trays of dahlias in her backyard growing area waiting to plant out. She even wrote the dahlia’s name on the tubers in Sharpie pen. Clever! I keep flat plastic containers around for this purpose, any takeout food container is good. It’s easy to tip the peat moss the dahlia bulbs are stored in into the container, then nestle the tubers in. If you have a bag of soilless potting mix, (and what gardener at this time of year doesn’t have a handy bag of soilless potting mix? If not, run and get some now!) add some of that to fill the container. Make sure the crown, where the stem used to be is pointing up. There is usually a little section of stem left where it was cut the previous fall.
Tubers can be arrayed outward in the pan, they don’t have to be vertical. If you don’t entirely cover the tuber, don’t worry. Then, water with warm water, as it absorbs into the peat and soiless mix more easily. This half-way planting process lets the nascent buds pop up, turn green and get growing. The dahlias will be fine for a few weeks like that till you plant them properly, either outside in soil or in large containers. Make sure they have an abundance of light, and water when the surface dries out.