When to plant bedding plants in Central Alberta

Is it safe to plant yet? That has to be one of the most asked questions in garden centres in May. Generally spea=king, most gardeners plant out at the end of May or beginning of June. However, Albertans are familiar with the old adage: "If you don't like the weather, wait a minute!" In other words, the weather in Central Alberta is not always predictable and can change drastically from one week to the next. So even though the weather for the past several days has been great and there seems to be no risk of frost, that doesn't mean we won't get frost later in the month. On the other hand, we may not have any more frost this spring. So what is a gardener to do?

One rule of thumb is that once the poplar trees have begun to leaf out, there is usually less risk of a hard killing frost. However, there may still be a risk of light frost and some plants are better able to survive temperatures 1 or 2 degrees below zero. These include pansies, violas, snapdragons, dracaena, dianthus, Swiss chard and flowering kale.

On the other hand, some plants are very sensitive not only to frost but also to cold nights even a few degrees above zero. These include the immensely popular new varieties of ipomoea (potato vine), and coleus as well as basil, impatiens, fuchsias and begonias. Do not plant these out until the nights are consistently a few degrees above freezing.

Many gardeners like to get a start on the season by planting their flower pots early. These folks are also prepared to bring their pots in at night if there is a risk of frost. Garages and covered decks are great for this: do not bring your pots into the house for any length of time unless in a very cool location. Homes generally do not have the necessary humidity and outdoor plants will suffer in this environment.

Plant lovers need to pay faithful attention to the weather forecast throughout the month of May and early June. Know your own area: if the Edmonton forecast is for 2o or 3o, it might mean below zero temperatures in low lying rural areas. If there is a risk of frost after you have planted out your bedding plants, do not fear. Save your old sheets and blankets and cover your plants on these nights and your plants will be protected. If you forget to cover, another solution is to get outside early before the sun hits your plants and water off the frost before it damages the plants.

Finally, a word on "hardening off" your plants. It is important to acclimatize your plants to the outdoors after taking them home from the greenhouse. Place your bedding plants in a shady area for a few days before moving them into the sunshine and planting them. This greatly reduces transplant shock. It is better to plant on cloudy days. On really hot and sunny days, it is best to plant in the evening or to cover your plants with a light sheet after planting.