I know, watching those massive hydrangea blossoms fade away as fall comes is a bit sad… But you we must be thankful for their amazing floral displays, and the lush foliage as well, which has kept us fresh over summer. But don’t worry; the new season is coming soon and these generous flowering shrubs will come back vigorous and lush again in spring. That is, only if you give them some tender loving care now, because winter is knocking at the door, with its cold temperatures and biting winds.
Taking care of hydrangeas in fall is key to their health, and, the good news is, you don’t have to do too much, however… It is easy to make mistakes, because not all hydrangeas are the same, and we gardeners need to give them what they really need.
Let’s find out what your hydrangeas are asking for now, in fall, so they can get through winter safe and sound, and fill your garden with colors and joy next year!
1: Put Your Hydrangeas “on a Diet” in Fall
I know, your hydrangeas have given you so much that the temptation to fertilize them in fall is hard to resist! But you need to be cruel to be kind in this season with them – you must “put them on a diet”! No, they don’t need to slim down, but fertilizing them at this stage is counterproductive.
Why? Put simply, if you fertilize your hydrangeas in fall, you will trick them into thinking that spring has come! If the weather is still mild, they will grow new buds and shoots just before winter comes, with its frost and… Well, you can see where we are going, they will waste energy, get damaged, and suffer a lot.
This is especially true if you use fast-release liquid fertilizers. So, feed your hydrangeas for the last time in Late August or early September, with a slow-release and balanced fertilizer. Compost is perfect, or a product with NPK 10-10-10 or 4-8-12, you don’t want to promote growth at this stage, so, in case, boost their roots with some potassium.
And after food…
2: Reduce or Stop Watering Hydrangeas in Fall
During summer, hydrangeas drink a lot; they need to keep all those leaves and flowers fresh and they do suffer from heat and drought. But fall is another story altogether… Rains start and your flowering shrubs are starting to slow down their metabolism, getting ready for winter dormancy.
So, adapt to rainfalls; if the season is wet, you can stop watering hydrangeas altogether, or in case it is dry or you have dry spells, only water your hydrangeas with 1 to 2 inches of water (2.5 to 5.0 cm) if necessary. Check that the top 2 or even 3 inches of soil (5.0 to 7.5 cm) are dry, then irrigate.
However, keep a closer eye on your potted hydrangeas, they may need more watering than those in your garden. But on the whole, less is more in fall!
3: Deadhead Your Hydrangeas in Fall
Is it really necessary to deadhead hydrangeas in fall? Some gardeners would say no, but I beg to disagree. It is true that the blossoms can survive on the branches through winter, but it is dangerous for two reasons
- They may rot or get very wet and attract infections and molds if the weather is humid.
- The blossoms are so massive and so abundant that they can prevent good ventilation, which hydrangeas need to keep healthy in winter.
So, deadhead them, and use them as dried flowers! You can let them dry on the branches and then remove them, anyway, but do it as soon as possible.
However, you shouldn’t try to snap off hydrangea blossoms with your fingers, as you do with many other flowers. The stems are far too tough and you risk damaging them. Use a sharp and sterile blade instead, and sterilize it before you move to the next plant.
Cut the stem just before the first healthy set of leaves. And the job is done!
4: Keep Checking for Pests and Diseases
Even if days are getting shorter and colder in fall, this usually humid season can still have a good climate for pests, infections and particularly fungi and molds. So, do keep checking for them.
On the other hand, as the foliage falls from your hydrangeas, it will be easier to look deep inside, while before it was hard, with all those leaves and flowers… Now it may be the time to spray some neem oil on the branches, to keep pests and molds a way, or treat any branches that may be infected (and they may not show it yet).
Just put a teaspoon of neem oil per liter of water and some liquid soap in a spray bottle and spray away abundantly all over your hydrangeas. You can repeat this every fortnight if you want, especially if you live in a warm and humid climate zone, or if you notice that other plants in your garden (or nearby, they don’t respect gates…) are affected.
5: Remove all Fallen Foliage from under Your Hydrangeas
When the leaves of your hydrangeas fall, don’t leave them there. Dead foliage in wet climates can be the breeding ground for fungi, but also pests and other infections. So, remove it and use it for your compost heap.
6: Improve Drainage for Your Hydrangeas in Fall
Now I am asking you to remove all the mulch from the base of your hydrangeas, and scatter 1 or 2 inches (2.5 to 5.0 cm) of coarse gardening sand to improve drainage. If your soil is very clayish, add some gypsum too. Just leave it on top; the rains will push it underground.
Good drainage is essential for hydrangeas in winter. To start with, it will most likely have worsened from spring, and these shrubs produce lots of organic matter. And if their roots don’t have enough aeration when it rains a lot, they may suffer and in serious cases even rot.
Then, if there is stagnant water and temperatures drop a lot, it may freeze, and this can seriously damage your hydrangeas’ roots.
Do you really need to remove all the mulch to add sand? No! It will filter through anyway, but I wanted to bring your attention to my next point…
7: Mulch Your Hydrangeas in Fall
If you have not mulched your hydrangeas yet, you must definitely do it in fall. On the other hand, if you had done it already, it is time to check it and replenish it, making sure there are at least 2 inches to protect them in winter.
Mulch has amazing effects; it keeps the soil warmer (in winter, and cooler in summer!), it preserves nutrients and drainage in the soil, it suppresses weeds and it also feeds your hydrangeas slowly as it decomposes.
Next…
8: Protect Your Potted Hydrangeas in Late Fall
Pay extra attention to your potted hydrangeas; they are more vulnerable that those you grow in your garden. They are usually small, but there’s an extra problem: cold gets to their roots much faster and more severely through the containers. So, here are a few things to do:
- Move your potted hydrangeas to a sheltered place.
- In cold regions (USDA zones 5 or 6 and below), wrap up the pot in some burlap and then wrap them again in plastic (so it doesn’t get wet).
- In USDA zones 4 to 3, you should also wrap the hydrangea in burlap or similar material, or use a rose cone.
- Wherever you are, remove the saucers! You don’t want them to collect water in fall and winter, which becomes stagnant.
This is, of course on top of what you do with hydrangeas grown in the garden.
9: In Cold Climates, Also Protect Your Garden Hydrangeas for Winter
Hydrangeas are really cold hardy, to USDA zone 3, but in USDA zones 3 to 4, it’s a good idea to protect them for winter, in case you have unexpectedly low temperatures. YI would do this in USDA zone 5 as well, if they are exposed to string winds.
How can you do it?
- You can wrap your hydrangea in burlap, or any similar breathable material.
- You can put a layer of straw at the base, it will produce heat (but don’t touch the trunk – straw can get wet and preserve humidity for long!)
- You could also use a plastic sheet instead of burlap, but make sure you place many holes in it, so your hydrangea can breathe. However, these usually look ugly in decorative gardens. You could use a rose cone for small plants, but they are expensive!
Finally, we move to a very important, but more complex point…
10: Pruning Hydrangeas in Fall: Is It a Good Idea?
Should you prune your hydrangeas in fall? Yes and no! It depends on what type of hydrangea you have! Let’s sort this out…
Hydrangeas fall in two categories, old wood and new wood varieties.
Old wood species will grow new flower buds on old branches, and they start producing them soon after the old blossoms are spent.
You must not prune old wood hydrangea varieties in fall! This is because you will literally cut off the newly born flower buds.
Of course, make an exception for dead, dying, dry or sick branches. But how do you know if your hydrangea is an old wood variety? Here they are!
- Bigleaf hydrangea (Hydrangea macrophylla)
- Climbing hydrangea (Hydrangea anomala subsp. petiolaris)
- Mountain hydrangea (Hydrangea serrata).
- Oakleaf hydrangea (Hydrangea quercifolia)
So, you must prune old wood hydrangeas as soon as they have finished flowering; take a couple of weeks’ time and get on with it – or it will be too late!
On the contrary, new wood hydrangeas will produce the new flower buds on the stems they will grow next year, so you can prune them in fall. And there are two species in this category:
- Panicle hydrangea (Hydrangea paniculata)
- Smooth hydrangea (Hydrangea arborescens).
Then, there’s a strange case, reblooming hydrangeas…They are a variety of Hydrangea macrophylla, and they bloom on both old and new branches. With them, you can give them a light trim in fall; you will lose some flowers in the first wave, but you will still get a good second show. But be very, very light, or they will become “late blooming hydrangeas”!
How can you prune new wood hydrangeas?
11: Prune New Wood Hydrangeas Correctly in Fall
Even if you are looking at a new wood hydrangea and you prune it incorrectly, you will cause damage and… Don’t expect much of a performance next year. So, let’s see how you can do this right.
First of all, the idea is simply to shape your hydrangea shrub for next year, keep it in size and of course, protect its health. And here are some simple rules for you to follow:
- Wait till the foliage has (almost) fully fallen, so you can see the branches clearly.
- Use sharp and sterile pruners, and remember to sterilize them after ach plant! Otherwise you will spread diseases!
- Prune all dry, dead and sick wood; however, only cut branches that are seriously sick, and try to save as much as you can.
- Decide which shape and size you want your hydrangea to have next year. But keep in mind that it won’t be smaller than this year.
- Prune competing branches; if they are too close together, or crossing heavily, they will become messy and prevent ventilation.
- Never prune more than 30% of your hydrangea.
Finally, keep in mind that while pruning for health is always a good idea, it is not really necessary to do it to keep it in size or shape; it depends on how you want your garden to look like after the winter season, when your hydrangeas wake up from their long slumber like sleeping beauties…
Some Simple Tender Loving Care in Fall – Thee Secret for Healthy and Bountiful Hydrangeas Next Year!
As I said, it’s not too hard to look after hydrangeas in fall. The most tricky part is distinguishing between new and old wood varieties, so, be careful. On the other hand, they are easy to tell apart… The rest is simple, and in some cases, it means no or less work than in summer, and now you know everything, like a professional. Treat your hydrangeas well in fall, and you will reap the benefits next year, with massive blooms and lots of healthy leaves!
Written By
Amber Noyes
Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.