Was in grocery store and saw some awesome hydrangeas....purple/blue etc. Now I am zone 5..would love to plant one (if any left for after MD sale)..but how to winter over? Garage attached to house-but not heated. Basement heated, but could set it up by the basement egress window.
Any information would be so appreciated
Mothers' Day zone 7/8
I would leave it in the garage as soon as it goes dormant and the leaves look dried out. The basement would be ok provided that it is not going to dry out due to the vents throwing hot air regularly at it. You need to water it some if the temps are above freezing. To prevent it from waking up too early, you may not want to keep it by a window at first, only once it "awakens" or if it stays "asleep" longer than in prior years.
Some people plant them outside, add 3-4" of mulch to protect the roots, surround them with chicken wire (that extends wider and taller than the plant) and then pile a ton of leaves to act as protection/insulation. Then top with something that will prevent the leaves from flying away (cardboard, rocks). Keep the chicken wire away from the tip ends (the more separation & the more leaves, the better insulated), where most invisible flower buds develop in July-August. And really pile the leaves on. Add more leaves in midwinter as the leaves will tend to settle by then. A location that protects them from bitter winter winds will help.
Do note that some of these types of hydrangeas were chosen to display nice bloomage and then be disposed (thrown away) so they may not be hardy at all and could even be problematic even in a cold garage. But heck, try anyways. If you plant them outside eventually, you will need the chicken wire winter protection always.
These grocery/florist store hydrangeas were made to bloom at a really weird time of the year so do not be surprised if they resist going dormant at the proper time on their first year (or maybe they go dormant earlier than others already in the ground). I had one that I bought in December (new leaves, blooming then) and it stayed awake throughout that winter. By July, the leaves looked sad and it stayed "awake" almost all the way thru the following December because we had very warm temps that following winter. It was weird seeing the leaves on that hydrangea (a-n-d the others) still not dormant so late in the growing season.
A H. macrophylla in my zone should have blooms in the broccoli stage at about now. In your zone, I would expect that they would be awakening and leafing out instead. Feel free to fertilize now when planted in the ground with about a 1/4 to 1/2" layer of organic compost or 1/2 to 1 cup of cottonseed meal. Apply it from the base outwards. That should be fine for the whole year. Top it off with 3-4" of mulch. You can also use a general purpose, slow release fertilizer (such as Osmocote 10-10-10) according to label directions. Feel free to add weak fertilizers like coffee grounds, liquid seaweed (it is also a foliar feed) and liquid fish but stop all fertilizers by the end of June.
If you decide to prune for whatever possible reason, remember that invisible flower buds will probably develop in July-August so prune -if you have to- by the end of June. The flowers can be left "on" thru winter. Most times, they will fall on their own. If not, you can deahead them (not prune them) once the plant leafs out.
Allow space for a 3-6' wide plant and you shold not need to prune often. These grocery store hydrangeas do not indicate how big they can get in the plant label so assume somewhere between 3-6'. In your short growing season, 4-5' may be right.
Note that H. macrophyllas have blooms that are sensitive to the surrounding soil's acidity or alkalinity. This is measured in terms of a scale called the pH scale. If the potting mix soil is acidic, the blooms turn blue. If the potting mix soil is alkaline, the blooms turn a shade of pink. If the potting mix soil is neutral or slightly acidic, the blooms may turn purple. As the roots begin to grow and get into the surrounding soil, the acidity/alkalinity of your garden's soil will be the one which controls the shade of bloom colors in the future.
As the blooms age, they turn a series of different colors, like greens, pinks/blues, sandy colors, etc (it varies depending on the hydrangea). Once they turn brown then that is it.
In your zone, I would prefer to plant reblooming hydrangeas though. I am way too lazy to be winter protecting and do not have enough leaves to do a good job, although some people use mulch or hay instead. The rebloomers do not need this much winter protection and their stems will usually dry out during the winter. But when the new stems grow from the base in Spring, these can produce flower buds and blooms even though the old stems died.
Good luck motts1,
Luis
Thank you so very much. I may start with the smallest one in the store....on the porch.
I do have the small green one "Little Envy?" ..still in pot. Keeping it safe as will have workmen with trucks coming in.