11 Tips For Getting Overwintered Hydrangeas to Rebloom

It was summer, you were at the garden center and there it was. The most beautiful hydrangea you have ever seen, and you needed it. Your garden needed it. You quickly bought it and planted it giving it a loving home. You watched the blossoms fade, and then the leaves began to drop. The seasons have changed. Now what?

Once your hydrangeas have gone to sleep for the winter it can feel like a very long time until you see those beautiful blooming hydrangeas again. When the days begin to get longer, you will notice signs of life. You should see buds that soon will open into leaves and flowers.

Whether you have overwintered a potted hydrangea or one in your garden these tips will send you down the right track toward a season full of beautiful hydrangea blossoms.

Be Patient

If your hydrangeas have produced healthy leaves but you are not seeing flowers yet, it might be too early! Hydrangeas bloom anywhere from mid-spring through the fall. Take a closer look at your plant and look for flower buds.

Their flower buds look like little heads of broccoli. Each one of the tiny buds is hiding away the beautiful and colorful petals that will soon be filling your garden.

If you don’t see anything that resembles these flower buds, be patient. I would not start to worry about a lack of flowers until mid-summer.

Prune at the Right Time

Hydrangeas can be referred to as “new wood” or “old wood” bloomers. This is important to consider because pruning at the wrong time could affect their blooms.

New wood bloomers produce flower buds growth from the current growing season. The species that bloom on new wood are Hydrangea arborescens and Hydrangea paniculata. They can be pruned either in the spring, fall, or not at all.

Old wood bloomers are Hydrangea macrophylla, quercifolia, and serrata. These species should be pruned very shortly after blooming has ended. This is because old wood bloomers will form their flower buds on those same stalks very shortly after the flowers have faded.

Pruning at the correct time is one of the best ways you can guarantee that your shrub will bloom again after the winter.

Start Your Spring Cleanup

Just as in the fall, it is a great idea to clean out your garden beds in the spring as well. Many leaves, branches, and other plant debris can end up in your garden. Any weeds that have begun to grow in the spring are water thieves.

Leaves and other debris can carry fungal diseases as well as insect eggs from one season to the next. While you are cleaning up your gardens, inspect your plants for any disease indicators or insects that might be waking up with the spring temperatures. The sooner you treat insects or diseases, the better off your plants will be all season long.

Diseases and insects can both negatively affect your upcoming season of flowers. Insects can munch on them leaving them riddled with holes. While diseases can cause the flower buds to rot beyond repair. 

Compost Your Garden Beds

This is a task that can be done in the spring or the fall. Once you have your gardens cleared of plant debris, and before you mulch your beds consider adding compost to your gardens. Compost is available in bags at garden centers, but many farms will sell their compost to gardeners. 

Compost adds organic matter to your soil which helps to enrich it. The compost acts as a natural fertilizer. I have seen the difference an application of compost makes in a garden. It can take struggling or even healthy plants to the next level. 

Right Plant, Right Hardiness Zone

If your hydrangea has not bloomed for an entire season and it looks like it may not bloom again this year, consider if you are growing a hydrangea species that is suitable for your zone.

For example, if you live in zone 5 and are growing a hydrangea that may only be hardy to zone 7 you run the risk of your flower buds dying over the winter or in the spring due to cold weather or a late frost.

If you have noticed this too late, you can dig up the shrub and plant it in a large container. When potted, they can be overwintered in a shed, garage, or in your home which could help to keep the flower buds safe.

Do yourself a favor and check the plant tag while you are still at the garden center and make sure that the plant you are choosing is suitable for your garden.

Focus on Nutrition

Hydrangeas do not need an intense fertilization schedule. However, there are a few situations that could negatively and positively affect their ability to produce flowers.

Aside from spring fertilization, you don’t need to go crazy fertilizing. If you have already overfed them, you may have hindered their flower formation.

Too much nitrogen will help the plant produce beautiful green foliage, but your plant will be so busy making those leaves that it will not have enough energy or the correct nutrients to produce flowers.

Fertilizers are made up of a balance of nitrogen, phosphorus, and potassium or N-P-K. To increase your blooms you will want the middle number or the P to be high.

A good fertilizer to use is flower tone which has a breakdown of 3-4-5. Phosphorous is the nutrient needed to form blooms. Applying this type of fertilizer can be done monthly throughout the summer.

Make Sure They Get Enough Sun

Most hydrangeas prefer to live in a little bit of shade. However, deep shade is not recommended for any flowering plant. Sunshine is needed for flowers to grow. If you are seeing production of smaller blooms, or no blooms at all, take a look at its sun exposure.

You may need to prune some tree branches from above the shrub or transplant altogether. Transplanting is best done in the spring or the fall, depending on when you have more time to tend to the shrub.

A lack of sunlight can also cause weak vegetative growth. This can cause drooping stems or stems that are leggy and unattractive.

Water When the Ground Thaws

Once the ground has thawed it is time to start watering your shrubs. Water is essential for growth to produce healthy leaves and beautiful flowers. If you allow the plant to dry out you will end up with dry and crispy leaves, as well as flower buds that will not open properly. 

Spring is a great time to install a soaker hose around the base of your plants. These hoses make it very simple to water the base of the plants, which is the ideal way to water. This will help keep any fungal diseases from splashing up onto your leaves and will help the water soak right into the roots.

Bring Potted Hydrangeas Outdoors

If you have overwintered hydrangeas indoors, don’t forget to bring them back outside! The purpose of bringing potted hydrangeas indoors is to protect the roots from cold winter temperatures. However, it is important that the plant experiences the elements of spring. 

The benefits of bringing your hydrangeas outdoors are to increase the amount of sunlight your plant will receive, as well as acclimating to where the pot will be spending the next few months. This will help the plant go through its natural life cycle, which does require some chilly temperatures. 

If you have an old wood bloomer growing in a container, such as a bigleaf hydrangea, be extra careful when you are moving the containers outside. This species will already have formed their flower buds. Any rubbing or bumping of the buds could strip them from the plant. 

Protect Plants from a Spring Freeze

There is nothing worse than a late spring freeze. These cold snaps have been known to wreck a season of blooms. If you have wrapped them during the winter, you could leave them wrapped until you are sure you are sure that the last frost date has entirely passed. Another option is to cover them just for these cold periods.

If you are concerned about your flower buds getting nipped by the cold, you could simply lay a light blanket over the top of your shrubs until the cold weather has passed.

You can remove the blankets in the morning to allow the shrub to warm up in the sun, and simply replace the blankets in the evening again. 

If you are growing in containers, just bring them inside for the duration of the cold snap to protect the flower buds.

Start Mulching

The finishing touch to any garden is mulch. Select a high-quality mulch that is popular in your area, I like to use pine bark. 

Mulch serves multiple purposes. The first of course is cosmetic. A freshly mulched garden is an easy way to add curb appeal to your yard. The second is for water retention. Not only does the mulch itself absorb a bit of moisture, but it helps hold moisture in the soil.

This in turn helps to prevent the hydrangeas from drying out and becoming stressed. Lastly, mulched gardens keep weeds and other pests away. Gardens with fewer weeds and pests are healthier and produce more prolific and stunning flowers.