Known as hortensias in many European countries, hydrangeas are immensely popular flowering plants originating in Asia and are a common sight in gardens the world over. With more than 75 species within the genus to choose from and quite specific growing demands, a question I regularly get asked does deer eat hydrangea?
If you have a deer problem in your garden, then you are going to want to know that your plants are safe before investing time and money into growing them.
In this article, I’ll be delving into the relationship between deer and hydrangea, as well as other pests, and sharing my knowledge of how safe it is to grow these showy – albeit time-consuming – shrubs.
Do Deer Eat Hydrangea?
The most accurate answer to this question is offered by the New Jersey Agricultural Experiment Station which went to the trouble of testing thousands of plant species to see just how attracted deer are to them.
Out of five hydrangea species tested for deer resistance (macrophylla, anomala petiolaris, quercifolia, paniculata, aborescens), all five were reported to be occasionally severely damaged.
This means that deer definitely eat hydrangea if they find any, but it’s not their favorite food and they won’t actively seek it out.
This, however, sounds more doom-and-gloom than it really is – according to the scientists behind the data supporting this, no plant is truly deer resistant.
Just like humans and all other animals – starving deer will eat literally anything to survive. This includes cacti, which could be considered to be the most deer resistant out of all plants, and in more extreme cases – other animals (even though deer are herbivorous).
Is It Safe for Deer to Eat Hydrangea?
In most cases, hydrangea isn’t lethal to deer, but it isn’t completely safe either. It’s dangerous for all animals (humans included) to eat hydrangea as it contains cyanogenic glycoside.
This compound is stored in the vacuole, which is a part of a cell, but it’s released and activated by enzymes when the plant is attacked. Therefore, when a deer starts eating a hydrangea, the plant starts releasing cyanide (albeit in small amounts).
The primary purpose of this compound is to deter herbivores from plants.
Once the enzymes activate the glycoside of cyanide, all that’s left is hydrogen cyanide, which is the actual poisonous compound. It’s a well-documented fact that cyanide is extremely dangerous, but for deer, it is even more dangerous.
Ruminant animals (horses, cattle, deer, wildebeest, American bison, etc.) are in more danger from cyanide poisoning because of microorganisms in their digestive tract.
What’s important to point out is that a deer has to eat plenty of hydrangeas to become poisoned. But, it’s highly unlikely that a deer will drop dead after eating four hydrangea leaves. The amount of cyanide found in hydrangea also isn’t as high as the amount found in some other plants.
If a deer is hungry enough to eat a large number of hydrangeas, however, the clinical sign will appear seemingly out of nowhere. Cyanide poisoning can develop within 20 minutes after ingestion.
The pulse of the animal will become quick, and muscle tremors will start slowly but become more extreme with time. The breathing will become labored and after a while – the animal will collapse and soon die.
To reiterate, however, deer would be to ingest great amounts of hydrangea to die from cyanide poisoning. The definition of ‘great amounts’ will all depend on the species of animal and their size.
So, while hydrangeas normally aren’t that dangerous to deer, they certainly have the potential to kill them if they eat too much.
A completely separate set of symptoms, including (but not limited to) vomiting, diarrhea, and stomach cramps can also occur. This, however, doesn’t have to be connected to cyanide poisoning. Because of this, ASPCA classifies hydrangeas as toxic plants.
Will Hydrangea Regrow After Deer Eat Them?
You’ll be happy to hear that your hydrangea will most definitely regrow after a deer nibbled on them. Luckily, deer are only interested in the flowers, not the stem. On occasion, they might eat a few leaves, but they’re mostly there for the flowers.
Since hydrangeas are flowering plants, they would lose those flowers at some point either way (usually in the autumn). They certainly have the potential to grow new flowers, and they most definitely will if it’s not too late in the year.
Are There Deer Resistant Hydrangea?
Unfortunately, no – no hydrangea species is less attractive to deer than any other species according to studies. It’s possible that climbing hydrangeas are somewhat more resistant, but that’s not because of their physical properties, but because they can be more difficult to get.
Not even climbing plants are completely safe, though, as deer are agile animals that can stretch if they need to.
How to Keep Deer from Eating Hydrangea
There is, unfortunately, nothing you can do to keep deer away from your hydrangeas specifically. To keep them safe, you’ll have to keep deer out of your garden as a whole.
Some gardeners think about caging their hydrangeas. While this is certainly an option, it is an option that I would not personally recommend. Hydrangeas need free space to grow, and even more importantly, they have some of the most beautiful flowers – it’d be a shame to cover them.
Because of this, I highly recommend that you use one (or multiple) of the methods below to keep deer out of your garden completely.
One thing to remember, though, is that it’s much easier to prevent deer from invading your garden than it is to shoo them away once they’re used to being in your garden.
Keeping Deer Out of Your Garden
While at first glance it can seem difficult to keep deer out of the garden, it’s actually easier to deter them compared to rabbits, moles, wild boars, or squirrels (which are essentially impossible to keep at bay).
Despite their jumping abilities and agility – deer are, at the end of the day, large animals that scare easily, and because of this, you can shoo them away with mechanical obstacles, scare strategies, and repellents.
Before you commit to any of these methods, there are a few things to keep in mind. Firstly, these methods are more effective if they’re implemented before the growing season. It’s also important to keep your garden free from deer attractants.
This includes fruit – especially fruit that’s dropped to the ground – as well as salt and feed. Some people like to feed deer, and while that’s commendable, it will only attract deer to your garden (and they’ll start going after your plants once they’ve eaten all the feed).
Lastly, remember that deer are much more likely to invade your garden in the winter when food in the wild is more scarce. This is great news for hydrangea growers since it’s likely that flowers will be spent come deer-foraging time.
One mechanical obstacle would be setting a metal cage around your hydrangeas, but as I already said – that’s not recommended. Erecting a tall metal fence around your entire garden, though, is recommended.
In fact, it’s the most effective method of keeping deer away. The only problem is – deer can jump high…very high. According to a study published in the Journal of Wildlife Management, you’ll need a 2.4 meter-tall (7 feet and 10 inches) fence if you want a guaranteed defense against deer getting in your garden.
There are very few instances in which deer can actually jump over such tall obstacles. Those situations usually include deer with incredible athletic capabilities and proper motivation, such as being chased by a predator.
Installing a fence is simple enough, but it can be quite costly. A metal fence of that height isn’t cheap, and if you have a very large garden, it could be a cost that your budget can’t handle.
Because of the cheaper price point and effectiveness against deer, many gardeners opt instead for plastic mesh fencing. This fence is also very thin, making it almost invisible, so it won’t diminish your garden’s looks that much. It is manufactured to be strong enough to keep deer away, though.
The type of fence you’re buying depends not only on deer but on other animal pests in your area too. For example – deer usually can’t break through soft fences, but wild boar, on the other hand, are known to just smash into them until they create a hole.
Depending on whether you’re dealing with just the deer or other animals too, you might have to install a strong fence or even call the professionals to do it.
Another animal you have to take into consideration is the rabbit or the hare – they’re great diggers. If they can’t squeeze through your fence, they’ll simply dig below it, which is why you will need to sink any newly installed fence into the soil.
Deer are not confrontational animals – unlike wild cats, mountain lions, or even boars – deer will always run if they’re challenged. Because of this, scaring them away is immensely effective.
One of the simplest (and the cheapest) scare mechanisms is connecting a sprinkler to a motion detector. Once a deer activates the motion detector, it’ll get a blast of water and that will definitely scare them off.
You can also use a motion detector with a loudspeaker or a blinking light. These two, however, have a few downsides. First of all, the speaker playing the sudden noise will most definitely scare the deer, but it’ll wake up the neighborhood too.
The blinking light has mixed results – deer don’t see the same way people do and a simple orange rotational light might not scare them off – they could simply ignore it.
Lastly, a scare strategy that many people forget about is using your dog. If there’s one thing you can count on it’s the natural instinct for self-preservation. A deer won’t enter a garden that has a barking dog inside. In many instances, your dog doesn’t even have to be barking – the deer might smell it from afar and stay back.
All you have to do is ensure that the fence in your garden is short enough for deer to jump over, but not so short that your dog can jump over it.
After testing them extensively, the Agricultural Experiment Station in Connecticut came to the conclusion that repellents do help, but they’re not a definitive solution for deer invasions.
To be exact, they reduce deer damage as deer don’t like the smell and/or the taste of the repellents, but they don’t eliminate the damage altogether. Why? Because repellents aren’t damaging to deer – they taste and smell bad, but they can’t harm deer.
With time, deer get used to them and learn to ignore them.
Fences are mechanical obstacles that deer can’t cross, while sprinklers, noises, and dogs are (from the perspective of a deer) extremely dangerous threats that could kill them if they don’t run away instantly.
Repellents are a nuisance – nothing more than that. The good news is that repellents enhance the effectiveness of other methods of deer control! Using them with a dog or a fence is a guarantee that no deer will invade your garden.
I’ll go into making your own deer repellent later, but now, let’s take a look at the most common deer-repelling ingredients and how they work.
Firstly, soap in bars. Simply hanging soap bars on the outside perimeter of your property boundaries will help keep deer away to a certain degree.
Soap doesn’t smell nice to them, and it’s also disgusting to eat in case a deer decides to take a bite. The extreme bitterness of the soap will teach deer to stay away.
A similar principle works with human hair – deer know what humans smell like and they’ll stay away if you have small bags (mesh bags, not plastic) hanging near your boundary.
There are dozens of popular commercial repellents. Some are soap-based, egg-based, and even capsaicin-based repellents. The latter type of repellent uses the active ingredient in chili peppers (capsaicin), making them spicy.
Animals naturally despise spicy foods, and a deer will most likely smell the spiciness in the air before even trying to bite into the plant. If it does take a bite, the animal is in for a nasty surprise.
Egg-based repellents are extremely effective too. In fact, an egg is the most recommended base for a homemade deer repellent, but I’ll get into that later. All you need to know for now is that egg-based repellents can be up to 100% effective in practice!
Soap-based repellents often smell like ammonia, which is a natural deterrent for deer. There are also repellents based on predator odor, although they are known not to be very effective in deer control.
Despite the positive results of egg-based repellents, I’d like to once again reinforce the understanding of how repellents work and point out that deer will most likely become used to them at some point.
Because of this, consider repellents as a secondary tool, not a primary deterrent.
Deer Resistant Plants as Repellents
A method often recommended by experts is growing plant species that deer avoid. Although I already explained that no plant is truly deer resistant, deer will rather walk away from a plant they don’t like than eat it. They’ll return to it only if they’re starving.
Planting such plants around the edge of your garden is sending a clear sign to the deer that there’s nothing edible inside. This method isn’t 100% effective, as deer can still ignore the plants and simply walk in, but it has shown some success in the field.
Such plants are the honeysuckle, golden bells, heather, daffodils, lily of the valley (extremely toxic), spruce, and barberry. You can find the entire list of extremely resistant and extremely susceptible plants here.
Making Home-Made Deer Repellent
Spending money on deer repellents is quite senseless when you can make your own at home – often just as effective and cheaper than commercial deer repellents.
Here are the most effective ingredients.
Smells That Repel Deer
The most effective smell is that of putrid eggs. Deer hate it and it will absolutely drive them mad. It isn’t the only effective smell, though, as it’s fine to use liquid soap and tabasco, which are both natural deterrents.
Some plants, like rosemary, basil, mint, and thyme are also deterring deer.
How to Make Home-Made Deer Repellent
Making deer repellent is very simple and here’s how to do it.
All you need is water and any of the ingredients mentioned above. In this example, I’ll share with you a recipe using eggs, but feel free to add anything else that you have to hand.
Step 1 – Grind the Ingredients
If you’re using solid ingredients such as eggs or rosemary, you’ll need to grind them in a blender before adding water. Make sure they’re ground finely.
Step 2 – Mix with Water
Mix the ground ingredients with water and make sure it’s mixed well. After that, filter out the solid ingredients (otherwise they’ll clog the sprayer).
If you’re using tabasco or soap, you can immediately go to this step and skip step 1.
Step 3 – Apply on Plants
Simply spray the mix onto plants, but remember that it needs to be reapplied periodically and after every rain.
Verdict: Do Deer Eat Hydrangea
Deer do eat hydrangeas, but they’re not at the top of their list of favorite plants. In fact, hydrangeas can cause cyanide poisoning and kill the animal if they eat enough of it, so they’re potentially dangerous for them. Some hydrangeas are also naturally resistant to deer because of their scent.
If the animals are hungry, though, they’ll eat hydrangeas and you’ll have to keep them out of your garden. Do this by installing a fence, using repellents, and scaring them away. You may also like to read Do Deer Eat Azaleas.