Question
I recently bought  a few miniature potted rose bushes from a garden centre and am wondering when we can transplant them into the earth. We are in zone 5 (Oshawa Canada) and the Spring temperature is about9 to 15 degrees celsius around this time.


Answer
Miniature rose bushes that you buy now from anywhere, have spent their whole life in a warm greenhouse hooked up to water and fertilizer. This means that they are very tender and need to be hardened off before planting. Most garden roses can go into the outside when there is no danger of a very hard frost left and this is the same for minis. There are two types of mini roses, one is a single stem plant and the others are 4 tiny cuttings placed in a pot. If yours are the latter, they may not really be happy in the garden and would be best to plant them into a larger pot and place where you can keep an eye on them. It is easy to tell which is which. However for now just place them on a cool, west window sill, spritz them daily with water (house temps are too dry and will encourage insects)place them outside in the sunshine when temps are warmer but bring them in for the night. Finally you will be able to plant them permanently in the garden. If they have flowers on them now, the colour and shape will change when they are planted outside. Greenhouse conditions are tropical ones.