How to winterize hydrangeas?

Winterizing Hydrangea Plants: Tips On Preventing Winter Kill In Hydrangeas

Most gardeners are fond of their hydrangea shrubs, whether they plant the pom-pom variety with globes of flower clusters, or shrubs with panicules or lacecap flowers. Hydrangea cold tolerance varies among varieties, so you may need to think about winterizing hydrangea plants. Winter kill on hydrangeas is not a pretty sight. Learn how to protect hydrangeas from cold in this article.

Hydrangea Cold Tolerance

Hydrangeas are among the easiest shrubs to grow. Easy care and undemanding, hydrangeas decorate your garden with their big, bold flowers for months on end. But when summer ends and winter sneaks in, it’s important to know how to protect hydrangeas from cold, and this involves hydrangea cold tolerance. Some varieties, like smooth hydrangea (“Annabelle”) and panicle, or PG hydrangea, are very cold hardy and bloom on new wood.

If these are the species in your garden, you don’t have to worry

about winter kill on hydrangea. They don’t need protection unless the temperature dips below negative 30 degrees Fahrenheit (-34 C.). Generally, leaving the old growth over winter, which can serve as additional winter interest, also helps protect these plants.

All of the other hydrangea varieties, including popular big leaf, form flowers during the previous growing season. These young buds need to survive the winter for you to see blossoms the following summer. If you are planting big leaf or one of the other varieties that bloom on old wood, you’ll want to learn about preventing winter kill on hydrangeas.

Winter Kill on Hydrangeas

Winter temperatures as well as winter winds can cause winter kill. This general term just means plant death during winter season. The low winter temperatures can kill the plant, or they might die because of drying out caused by winds.

Because hydrangeas go dormant during the winter, you may not notice winter kill on hydrangeas until spring. You’re first hint of damage may be the fact that no green shoots emerge from you hydrangea in March or April.

Preventing winter kill in hydrangeas is a matter of protecting the shrubs, including their nascent buds, from winter’s wrath. A good way to start winterizing hydrangeas is to lay down a thick layer of mulch over their root area. Straw works well for this.

For even greater protection, cover the shrub with a wire cage, or build a cage around it with strong stakes and chicken wire. Wrap burlap or insulation cloth around the cage. You’ll also want to water the plant generously just before the ground freezes.

Winter Protection of Hydrangeas

Protecting Mopheads and Lacecaps in Winter

The information on this page is for H. macrophylla, which is the typical blue and pink mophead or lacecap hydrangea. Paniculata and smooth hydrangeas do not need protection in the United States and most of Canada.

Hydrangeas that experience winter temperatures of no less than 5-10 degrees do not need winter protection. If the temperature falls into the single digits for only a few hours at a time, the hydrangea should not be harmed.

NOTE: One word of warning- Before purchasing a hydrangea that you know will need winter protection to bloom in your area, keep this in mind. While the hydrangea is small it will be easy to protect, but as it grows larger, the task will become much more difficult and may, in time, grow too tedious to continue.

Suggestions for Winter Protection

Most methods of protection start with a frame around the hydrangea. This can be sturdy stakes surrounded by chicken wire, burlap, or other material that allows air to circulate (Plastic is not recommended although some find it useful).

The sketch to the right (a copy of which you will undoubtedly want to order for your art collection) shows a dormant hydrangea surrounded by a wire cage. (One reader suggested lining the inside of this cage with cardboard)

Next, an insulating material such as oak leaves, pine straw, or something similar, is worked down into the enclosure. Be careful not to break the tips off any of the branches as this is where the flower buds have already formed. (One reader suggested enclosing the entire cage, at this point, with insulation cloth.) This must be left on the hydrangea all winter and into the spring until the last possible frost has past. When it is uncovered, the hydrangea will already have started to leaf out.

Important: Since hydrangeas tend to set their blooms on the ends of the branches, it is important to keep these covered all winter. Most insulating materials will pack down somewhat during the winter and expose the branch tips, so the material must either be replaced or secured in place.

WARNING: Luc Balemans, a hydrangea expert in Belgium, warns that some winter covers (similar to the one at the left) may rub the ends off the branches in windy weather and, in turn, rub off the bloom buds. These all-important bloom buds on branch ends should be protected with a layer of leaves or other material before covering.

As mentioned above, leaves often settle during the winter, leaving delicate buds exposed. One gardener suggests that oak leaves are particularly effective insulation since they do not pack down like other material. Another gardener recommended keeping extra bags of leaves in an area where they will not freeze. These can then be used to refresh the leaf insulation as it settles over the winter. For those that don’t have time to go to your local garden center or looking for something a little cheaper we were able to find some good options online.

Protecting Hydrangeas in Ontario, Canada

Below is a picture of the “snowcone” that protects Sylvia’s ‘Lemon Wave’ hydrangea (makes me what to add eyes and a carrot nose!).

The snow cone is a purchased Styrofoam cone. Sylvia gardens in Ontario, Canada. She says that each fall she “snips off the branches so they will fit under my snow cone. Even though I lose some buds, I still get plenty for the next summer. I tie them together with rope and then put the snow cone over. I stuff the snow cone with dry clippings from my boxwood hedge.”

This hydrangea has been growing in Sylvia’s garden for 5 years.

WARNING: Snipping off the ends of the stems of most hydrangeas causes some flower loss unless it is done before August.

Protecting Hydrangeas in Massachusetts

Bob, in Massachusetts, has developed an interesting twist to the common method of protecting hydrangeas with an insulated cage. Bob was having difficulty with moisture seeping through the leaves and freezing on the plant. He states that the reasons for using Styrofoam over the cage is “the Styrofoam will protect the plant from severe freezing, as well as preventing snow from melting and saturating the leaves which would then freeze, encapsulating the hydrangea buds. This would probably kill them.” Maybe his being a retired mechanical design engineer explains why this structure is so perfectly and carefully made. Below is a picture of the top half of the cage surrounding one of his hydrangeas.

The following is a description of Bob’s procedure:

1. Fill plant with leaves (carefully stuff leaves into the branches of the plant)

2. Pull outer stems vertical (up) and tie them together.

3. Place 4′ high fencing, lined on the inside with plastic sheeting, around the plant, leaving 1 foot of space all around.

4. Fill this space with leaves (being careful not to knock off any buds)

5. Bring ends of fence together, and overlap so as to partially compress the leaves, and secure.

6. Fill to the top with leaves.

7. Cut a 4 foot diameter x 1″ thick piece of Styrofoam and force inside the top of the fence, contacting the leaves.*

8. If your hydrangea is smaller, a 2 foot or 3 foot diameter of Styrofoam may be cut.

*Bob says that sheets of Styrofoam can be purchased at home goods department store in various thicknesses. He uses a “radius compass” to draw the circle on the Styrofoam, but I imagine a pencil on a string would also work for us non-engineers. 😉

OTHER IDEAS FOR PROTECTING POTTED HYDRANGEAS

Protecting hydrangeas in large planters with foam.

Not pretty but gets the job done!

Protecting Potted Hydrangeas With Insulation

AN UNUSUAL WAY TO PROTECT HYDRANGEAS – FLATTEN THEM !

NOTE: As with several techniques on this site, we can neither recommend the following technique nor take credit for it. But it is such a wonderfully creative and unusual idea, that I wanted to share it with the visitors to this site. This is a highly unconventional way to protect hydrangeas sent to me from a Canadian visitor to this site (Maria).

I can give you no more information other than what you will read below. Basically, Maria describes how she flattens her whole hydrangea plant beneath sheets of cardboard and bricks. Maria writes:

“I live In Ottawa, Ontario Canada, and have been a very crazy hydrangea fan. In my very large previous garden I had quite a large collection of them. I was told by an old German lady that owns one of the nurseries here to cover hydrangeas this way, and it does work.

Find a middle of the shrub, gently push down each side of the plant (groups of branches) towards the ground, cover each with cardboard. (hunt for large TV boxes). When they get larger, I need help to hold them down. I use bricks to hold down the cardboard, then I put leaves over it all, and then white insulating cloth, and finally more brick to hold it all down. Later, the snow helps to push the whole thing down,.. and it has worked for me in this climate. Love your site, Maria”

In another e-mail, Maria assured me that the hydrangeas pop back up in the spring and look like normal hydrangea shrubs. Isn’t this amazing? I wish she’d sent a picture!

HYDRANGEAS IN POTS:

If you live in a very cold area, you might try growing hydrangeas in large pots and putting them in a cellar or garage that freezes only lightly.

Admittedly, large pots are difficult to handle, but hydrangeas will NOT do well in smaller pots. Their roots are too aggressive and quickly fill the smaller pots.

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Preparing Your Hydrangeas for Winter

Getting Your Hydrangeas Ready for Winter

If your hydrangeas live in a cold climate, late fall weather is the perfect time for them to harden off, you can use this same time to prepare them to make it through the coming winter.

Exactly what you do depends on what kind of hydrangea you have and where it lives. But the good news is the only ones you really have to worry about are your hydrangeas that flower on old wood. Their flowers have been forming on the plants since August and those are the buds that you need to protect.

For the most part, climbing and oakleaf hydrangea flower buds are more winter hardy than those of bigleaf hydrangeas. In my zone 5 gardens, when my bigleaf hydrangeas have suffered winterkill, my oakleaf and climbing hydrangeas have flowered profusely with no protection.

What this all comes down to is the one kind of hydrangea that needs your intervention: bigleaf hydrangea (macrophylla). I call it the troublemaker.

Make an A-Frame for Hydrangea Protection

Snow can be a protective blanket in some cases or it can break and distort the stems when it is heavy and wet. In view of that, one thing to consider is an A-frame to shunt off the snow. It still allows the snow to build up at the base of the plant which can be a good insulator. You can build an A-Frame from a discarded pallet as shown in the photo or buy one. There are lots of DIY plans online.

You can protect your plant by erecting some kind of temporary windbreak. Hydrangea macrophylla buds are killed by icy winter winds which desiccate tender flower buds.

hydrangeas dieing back in winter

When the tag is not a descriptive label, it is difficult to know the exact variety and that usually helps answer the question. If you saw colored round blooms when you bought it then it is probably a Hydrangea macrophylla. In general, hydrangeas are deciduous so they loose the leaves in the winter months (although I have one oakleaf hydrangea that was not in the mood to do that this year). H. macrophylla develops invisible flower buds in July-August and these open in your Spring. However, they are usually hardy to Zone 6 only (a few to Zone 7). In colder zones like yours, the stems (where the flower buds are) dry out and die. The plants roots are usually ok though so they generate growth from the crown or base again. However, these new stems will not develop flower buds until July-August (unless this variety is one that reblooms but that is rare). To prevent loosing the stems and the flower buds, try winter protection. Do a search on the forum for the phrase ‘winter protection’ for additional information. The concept is to somehow protect the sides and top of the plant by filling the area with mulch or leaves in the Fall (when the plant goes dormant and before extremely cold temps will damage the invisible flower buds. A piece of cardboard on top with rocks makes sure that the mulch does not fly away and some chicken wire around the bush helps with that too.
It is probably too late to protect now. Wait to prune the dead looking sticks until sometime in May as they will leaf out late sometimes. If they do not leaf out by mid-May then assume there probably will not be flower buds and the stems died out. You can prune those at ground level.
A rebloomer variety of H. Macrophyllas -such as the Endless Summer Series, the Let’s Dance Series, the Forever Series- will suffer from dieback but the new stems will generate blooms (albeit later than normal, probably in June-July) since you have to let the stems grow a little so they generate flower buds and bloom.
Another alternative is to grow them in pots and bring them inside into a garage or shed when the plant goes dormant. Just do not forget to water it once every week or once every two weeks.
Yet anbother alternative would be to use hydrangea varieties that are more hardy. In Zone 5, you can try: oakleaf hydrangeas (the leaves look like oak leaves and the leaves also look very nice in the Fall), paniculatas (they have panicle shaped blooms) and arborescens (also called the smooth or wild hydrangea, arborescens is a hydrangea native to the US and is best known by the Annabelle Hydrangea and its newer “versions”).
I hope this helps,
Luis

Hydrangea Winter Care: How To Protect Hydrangeas From Winter Cold And Wind

Proper hydrangea winter care will determine the success and quantity of next summer’s blooms. The key to hydrangea winter protection is to protect your plant, whether in a pot or in the ground, prior to the first frost of winter through the last frost the following spring. Let’s look at what you need to do for your hydrangea in winter.

How to Cut Back Hydrangea Plants for the Winter

The first step in hydrangea winter care is to cut away the old wood at the base of the plant, and remove any dead or weak branches by cutting them off at their base. Be careful not to cut off healthy wood, as this wood will be where your hydrangea will bloom from next year.

In-ground Hydrangeas – Winter Protection

Protect your in-ground hydrangea in winter by making a frame around the plant by using stakes. Wrap chicken wire around the stakes to form a cage. Fill the cage with pine needles and/or leaves to fully insulate your plant.

Oak leaves work well because they do not settle as easily as other materials. Keep a bag of leaves from your fall leaf raking pile so that you can fill the cage throughout the winter as the insulation settles.

Be careful not to snap off the ends of the branches as you fill the cage or all will be for naught and you won’t have those gorgeous blooms next summer.

Potted Hydrangeas – Winter Protection

The best hydrangea winter protection for potted plants is to bring them inside prior to the first frost. If they are too cumbersome to move, they can remain outside and be protected by covering the entire pot and plant. One method is to use foam insulation to protect your potted plants.

Importance of Hydrangea Winter Care

How to protect hydrangeas from winter cold and wind can seem labor intensive. However, once you have your plant’s winter home in place, the remainder of the winter only will require a little housekeeping to maintain successful hydrangea winter protection.

Whether you’re deciding how to cut back hydrangea plants for the winter or how to protect hydrangeas from winter cold and wind, keep in mind that taking a little care of your hydrangea in winter will grace you with lush bushes and beautiful flowers next summer.

How to Winterize Hydrangeas

Hydrangeas need protection from harsh winter temperatures, freeze, thaw, and drying winds. Depending on your climate zone, you may need more or less protection to winterize hydrangeas. Some gardening experts say that H. macrophylla—the common mophead or lacecap hydrangeas in shades of blue and pink—are the only hydrangeas that really need winter protection. Annabelle and Pee Gee (paniculata) do not require this treatment.

Here is a simple blueprint. If winter temperatures do not go below five to 10 degrees Fahrenheit, or only dip into single digits for an hour or so, hydrangeas should be okay without winterizing. But if winter protection is required, the steps are simple and straightforward. Here’s what to do.

Step 1 – Assemble Materials

Gather all materials for winterizing when hydrangeas go into dormancy, which is after all the leaves have fallen off.

Step 2 – Lay Out Stakes and Surround with Chicken Wire

For the cage winterization method for hydrangeas, lay out the stakes and pound them into the ground around the plants. Stretch chicken wire around the outside of the stakes. Cut the material to fit and attach with garden clips, wire, or plastic ties.

You can also insulate by wrapping burlap around the stakes.

Step 3 – Tie Back Hydrangeas

Since the object of winterizing mophead and lacecap hydrangeas – which set blooms on old growth wood – is to protect the buds from temperature extremes, tie the branches loosely together inside the chicken wire cage or burlap enclosure.

Step 4 – Surround with Mulch

Next, add the insulating material inside the enclosure, working down to the base of the hydrangeas. Be careful not to damage the tips of the branches, which is where the buds will bloom come spring.

For additional protection, you can add insulation cloth inside the entire cage.

Step 5 – Cover with Styrofoam

This step may not be necessary, but in areas where there is heavy snowfall, it is probably a good precaution. Once the cage has been constructed and insulating material added, cut a one-inch thick piece of styrofoam the diameter of the cage. Place it inside the top of the cage, gently compressing the leaves in the process.

Other Winterizing Methods

For potted hydrangeas, simply cover them with sufficient protective material and keep them out of harsh winter winds. You can lay the pots on their sides on a waterproof tarp and fill with insulating material. Another method involves placing styrofoam cones over the top of the plants.

Alternatively, tape large pieces of one-inch thick foam padding into place around and over the top of the potted hydrangeas. Of course, you can also bring smaller potted hydrangeas inside to a basement or garage that only freezes lightly.

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