Preparing Your Hydrangeas For Winter

It’s time to start preparing your hydrangeas for winter. With autumn’s official start right around the corner on September 22, it’ a good time to start to get your plants ready for winter while the weather is still pleasant and mild.

Snow on ornamental grass makes a lovely winter scene.

PREPARING YOUR HYDRANGEAS: CHANGING YOUR FLOWER COLOR

First thing to think about is what you might need to do for your bigleaf (macrophylla) and mountain (serrata) hydrangeas. A big item for many people is changing the flower color to pink or blue. If that is you, be sure your plant is one that is pH sensitive and can indeed change its flower color. If so, autumn is the time to add the proper amendment so the plant can absorb it in time for next year.

You need to do a soil test to check the pH of the soil. The results will guide you in how much to amend your soil. Adding aluminum sulfate will change the flower color to blue (make the soil more acidic) while adding lime will change the flower color to pink (make the soil more alkaline). You can buy a pH soil test kit at your favorite garden center or box store like Home Depot or Lowe’s.

DIY Soil Test Kit can be used to check soil pH

Don’t guess: do the test so you get it right. Remember that the soil will always try to revert to its natural state so once you start this amending process, you will have to repeat the process to maintain your desired flower color.

PREPARING YOUR HYDRANGEAS: LEAF SPOT ISSUES

A second fall activity that will help you grow a healthier hydrangea is to take care of any plant that has had leaf spot issues this season. Take a moment or two and inspect all your hydrangeas. If any of them have suffered this past season from leaf spot diseases as seen in the photo, you can go a long way to preventing them next year with a good clean up starting now.

Hydrangeas with leaf spot issues need attention now.

If you want to know more about hydrangea leaf spot issues, there’s a terrific academic paper from Tennessee State University Extension. Although the authors discuss treating the conditions with multiple products, most of them aren’t available to home gardeners and are not organic (my preferred approach) with the exception of copper and Neem oil. You may want to lay in a supply of either of those two treatments at the end of the season when garden centers put things on sale. They are good all-around organic treatments for many fungal issues in the home garden.

Make sure you disinfect your clippers with your favorite disinfectant. I like a spray of Lysol or a disinfecting wipe. You don’t want to spread anything to any other plant. Ditto for your gloves/bare hands.

PREPARING YOUR HYDRANGEAS: DEADHEADING

While you’re at it, you might think it’s a good idea to remove your spent flowers. DON’T DO THAT! Those ratty looking flowers will protect the flower buds that will develop over the next few months. Those flower buds have to survive the winter and need all the help they can get. Since you have nothing to gain by deadheading the plant now, try to live with the cosmetic flaw. Remember that cutting the plant now will stimulate it which you don’t want to do. You want the plant to settle down, get ready for its winter rest and send its strength to the roots. So don’t mess up its brains by cutting it.

No hydrangea pruning this time of year.

Make sure you disinfect your clippers with your favorite disinfectant. I like a spray of Lysol or a disinfecting wipe. You don’t want to spread anything to any other plant. Ditto for your gloves/bare hands.