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What is the latest date to fertilize roses before winter?

GGardens
10 years ago

I live in zone 8 close to Seattle on the Olympic Pennisula; we usually have mild winters with only a few days of temps below 30 F. When should I last fertilize my roses before winter?

Comments (4)

  • michaelg
    10 years ago

    As a general procedure, I would say, determine when freezes of 28F or so will stop roses from growing and blooming in your area, and make your last fertilizing no later than six weeks before that. If you are using a fertilizer with fast nitrogen, it will be pretty well used up in that interval, so you won't be wasting fertilizer or causing pollution pointlessly.

    In your climate, there should be no winter damage beyond the soft tips regardless of how fast or slowly the roses are growing.

    Many growers feel they need to stop fertilizer in late summer. But frankly, we have no evidence that stopping fertilizer early increases winter hardiness in areas where winter damage does occur. Regardless of our attempts to control things, repeat-blooming roses are going to keep growing until the cold or lack of water stops them. So I fertilize in order to maximize fall bloom. I also continue deadheading through the fall.

    After winter lows of around 5F, I have essentially no cane damage.

  • seil zone 6b MI
    10 years ago

    That's a tough question. Michael has given you the general rule about 6 weeks before your first hard freeze but with the weather the way it's been who really knows any more when that will happen. I used to cut my last roses just before Halloween. Now it's more likely to be Thanksgiving for me. And I'm a heretic anyway. I fertilize mine through fall. Yes, it stimulates some new growth that will die over winter but I've found that mine don't stop growing whether I fertilize them or not. More than likely I'm going to lose some cane during the winter. I'd rather that be the new growth from last fall than the established canes. What I do want is for them to go into winter healthy and well fed so they have plenty of stored energy for spring when it might be two or three false starts before it sticks for real. The more energy they can store in fall the more they'll have to rebound with in the spring.

  • michaelg
    10 years ago

    I don't disagree with what Seil says. I fertilize until Oct. 1, so that fertilizer is available until local roses wind down sometime in November.

    If you fertilize with slow organic sources of nitrogen, you have little control over the amount of nitrogen in the soil moisture at a particular time. However, some N will continue to be released in the fall from spring and summer fertilizing. The rate of release will slow down as the temperature drops, which is fine because the plants will be using less nutrients anyway. I wouldn't apply slow organic fertilizer in the fall unless I expected roses to continue to grow through most of the winter.

  • mgleason56
    10 years ago

    I was getting ready to post and then saw Seil's and it is EXACTLY what I would have written.