My gardens are full of hydrangeas, azaleas, roses, and numerous other Spring leaving and budding flowers. I have fresh day lilies opening blooms and other perennials still flowering? This is almost December and all my plants are freshly budded as if it were April. Will any of this out of season setting of leaves and flower buds survive if we have severe winter weather? And, what happens next Spring since the plants have already put on leaves that succumbed to winter weather?
Clackamas County Oregon
Fall weather varies quite a bit here. This year we've had an extended fall without a "hard frost", but we also had great fall color for a long time. In the Portland area the first date of frost can be from early October until late November, Frost Dates in Multnomah County http://www.multnomahmastergardeners.org/sgp-frostdates. Shrubs and perennials also vary in what triggers them to go dormant. Some fold up shop at the first sign of cold weather, and others can tolerate considerable cold before going dormant. Months of cold weather remain, so the dormant period still occurs normally.
Some hydrangeas bloom regularly in the fall. Some experts even prune hydrangeas in the fall/ This excellent article gives a good summary of hydrangea care, General Care for Hydrangeas https://extension.oregonstate.edu/gardening/flowers-shrubs-trees/general-care-hydrangeas.
Some azaleas will rebloom in the fall with the right conditions. (Azalea Information https://www.azaleas.org/about-azaleas/). Roses often bloom late into fall, even winter. Most roses bloom on new wood, which is why they are pruned back in the spring - to stimulate new growth and blooms.
Your plants should be fine, and bloom normally in the spring, if that is the normal bloom time for them. Growing plants is always an adventure, though. A big part of the fun of gardening is always seeing new events and learning from them. A spurt of new, soft growth in the fall can be damaged in winter weather, but normal growth should be fine.