Question
QUESTION: I have planted 9 new hybrid rose bushes for the 1st time.
I live in nothwestern ontario,canada.I have buried the roses
with soil and covered them with straw.My qestion is when is it
safe to stat uncovering them.

ANSWER: In your area, wait until there is no danger of a hard frost. I would also wait until you won't be getting more than a couple of days of light frosts in the morning. Roses can take frosts but not many days in a row as this will damage the new growth. When the mornings are cold, but no hard frosts, start by removing your straw first and then finally in a weeks time, remove the soil. Because you get really cold winters, remember not to fertilize your roses after the end ofAugust and don't dead head them either. This will make them slowly go dormant and because the canes will have drawn down the moisture before you get any hard frosts, your roses will go through your winters much better. Most hybrid teas die because they were not tough enough to go through winter's cold and fertilizing them late in the season is what causes them to not live or get damaged by the cold.

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QUESTION: Thank you for the great advice. I will try this as you suggested.
I would also like to know how long after i uncover them,can i give them a drink and when can i start fertilizing and with what do you sugest.

Answer
You can put fertilizer on any time after you uncover them but fertilizer usually doesn't work until the outside temperature is around 70'  Most rose fertilizers are fine for all roses. If you are an organic gardener, then fish fertilizer is the roses favourite. You can dilute it and pour it all around the base of the rose bush once a month or you can use it as a foliar spray every month.