Planting annuals in Toronto

(Question)

In downtown Toronto I have a raised wall about 3′ high and is made of wood and along the top of this wall are 9 window boxes. This is bordering a quiet lane way and faces south with western exposure too. I have bought Martha Washington geraniums and bacopa. I am wondering if it is okay to plant them now or when would be your recommendation?
Thankyou for your thoughts and advice.

(Answer)

It sounds like your window boxes are located in a warm and sheltered position. However, traditionally one waits to plant annuals when the chance of frost has vanished.  This is usually around the Victoria Day holiday in May.  While the weather is warm during the day at this time of year  it can get quite cold in the evenings. In the meantime keep your purchased plants in a warm spot, in their pots or trays.  Keep them watered and listen to the weather forecast.  If there’s a chance of it getting really cold overnight, cover plants with some burlap or garden fabric.   In three weeks time it should be ok to plant your purchases.