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You have some leftover coffee grounds in your kitchen and are wondering where you can make use of them. You’ve heard that some plants like coffee grounds but aren’t sure if they’ll suit your hydrangea bushes. So, are coffee grounds good for hydrangeas?
Hydrangeas thrive at a pH level of 5.0 to 6.5 and can benefit from being fertilized with coffee grounds, especially in neutral or alkaline soil. Lowering the pH of a hydrangea’s surrounding soil can also produce beautiful blue blossoms, but soil acidity must still be closely monitored.
Keep reading to learn more about how to fertilize hydrangeas with coffee grounds, the best time of year to do so, and how using coffee grounds on your hydrangeas can impact shrub health and beauty.
Do Hydrangeas Benefit from Coffee Grounds?
Hydrangeas thrive in moderately acidic soil and respond well to coffee grounds. They can tolerate a lower pH level than many other plant varieties and enjoy the nutritional benefits of coffee grounds, as well as the benefits to local soil.
This is especially true if your soil’s pH level is naturally 6.5 or above. Suppose your soil is more alkaline, clay-rich, or calcium-heavy. In that case, it may be difficult, if not impossible, to grow a hydrangea without treating the soil with acidic components like coffee grounds or growing your hydrangea in a raised bed.
Hydrangeas respond well to coffee grounds as a direct fertilizer or as part of the compost. Coffee grounds are also great for soil in general and can add several key nutrients and benefits to any garden.
What Do Coffee Grounds Add to Soil?
Coffee grounds are naturally acidic, and this acidity, when added to soil, makes it easier for plants to absorb nutrients and helps them grow bigger and faster. This is especially true if coffee grounds are added to soil at the beginning of the growing season.
Coffee grounds also break down in soil fairly quickly, don’t add much bulk to the earth, and are loved by earthworms as a food source and a digestive aid. Worms will often use coffee beans in very much the same way that some birds use pebbles in their crop to help them break down or digest food.
Happy, well-fed worms will add vital nitrogen to the soil through their castings, and the tunnels that worms create as they move through the soil can help naturally fill the earth and make it more hospitable for domesticated plant life.
So now that you know all of the benefits that coffee grounds can add to your soil and your growing hydrangea, where can you get some coffee grounds quickly?
How Can I Get Ahold of Coffee Grounds?
If you’re an avid coffee drinker, you already have a lot of coffee in your kitchen, and you’ve probably been tossing used coffee grounds for years. This can become a valuable food source for your garden, so stop throwing used grounds in the trash!
Your coffee grounds can come from any number of devices or machines, such as;
- A drip coffee maker
- A pour-over system
- Keurig single-serve pods
- A French press
- A coffee siphoner system
All of these methods will yield used coffee grounds that can be saved and used on your hydrangea bushes later. We recommend storing your used coffee grounds in an easy-to-wash stainless steel bucket with a tightly fitting lid. This will help reduce odor and keep your grounds fresher.
Be sure to use these grounds within two days to avoid mold growth and to avoid attracting gnats or fruit flies to your kitchen.
Another great way to get even more coffee grounds is to hit up your local cafe, whether a national chain or a local coffee shop. Ask if you could have some of their used coffee grounds and arrange a time and a date to pick these up. If they agree, consider leaving a small tip to show appreciation, and bring your bucket to help collect the grounds.
So now that you’ve got plenty of coffee grounds, what benefits can these gritty little dregs add to your hydrangeas?
How Do Coffee Grounds Affect Hydrangea Blooms?
Some gardeners have found that adding coffee grounds to hydrangea bushes can turn their blooms from purple to blue. A soil pH level of 5.0 to 5.5 generally results in hydrangea blooms that are a beautiful powdery blue.
A soil pH of 6.0 or above will yield more pink and purple blooms. This is because a more acidic soil allows the hydrangea bush to absorb higher levels of beneficial metals like aluminum, which can encourage blue blossoms.
Adding coffee grounds to hydrangea bushes may cause some, most, or all blossoms to turn from purple or pink to blue. It depends upon how your hydrangea bush absorbs aluminum and how it responds to more acidic soil.
Coffee grounds added to soil that is 6.0 or greater in pH throughout the growing and blossoming season will gradually lower the pH of the soil. You’ll have to test your soil’s pH levels weekly to ensure they are not becoming too acidic.
This blue color is the envy of many gardeners, and using coffee grounds is a natural and simple way to achieve this. So how should you apply coffee grounds to your hydrangea bush?
How Can I Fertilize Hydrangeas With Coffee Grounds?
A simple way to fertilize your hydrangea bush with coffee grounds is to sprinkle them on top of the soil around the base of your hydrangea and then water the grounds into the soil. Microbes and earthworms will also do a great job of pulling those coffee grounds into the earth and closer to the root system.
Raw, fresh coffee grounds will be much more acidic than brewed coffee, but both can be used. 1 – 2 cups per treatment are appropriate. Fresh, ground coffee should be sprinkled every other week, and the soil’s pH level should be tested weekly.
Used coffee grounds can be applied every week, as their acidity is a bit less intense and will not lower the pH level as steeply. Still, you should check your soil’s acidity weekly.
Another great way to use coffee grounds to fertilize hydrangeas is to allow used coffee grounds to seep in water overnight. Use 1 cup of used coffee grounds per 1 gallon of water. Make sure you water with a watering can whose perforations are large enough for the grounds to get through. Shake the watering can vigorously, and then water, ideally in the early morning.
This process can be repeated weekly and can do wonders to help encourage healthy, beautiful blue hydrangea blossoms. So, when is the best time to treat hydrangeas with coffee grounds? Can you do this year-round?
When Should I Add Coffee Grounds to Hydrangeas?
Hydrangeas generally begin blooming in the later summer and early autumn. They’ll sprout leaves in the Spring months, but the blooms likely won’t appear until July. So the best time to begin treating your hydrangeas with coffee grounds is in early summer before blooms appear.
This will allow your hydrangea plants to absorb ample amounts of aluminum before blooming. Treat the soil weekly with used coffee grounds and bi-weekly with raw coffee grounds, checking the soil pH level often.
Once your hydrangea begins to bloom, continue fertilizing bi-weekly for the best chance of healthy, blue blossoms. If the soil’s pH falls below 5.3, skip a couple of weeks’ worth of treatment, as overly acidic soil can harm a hydrangea.
Cease fertilizing your hydrangea by early autumn to allow your hydrangea to prepare for winter hibernation. Late August is generally a good time to ease off coffee treatments, though this will largely depend on your growing season. Your hydrangea may bloom a bit beyond this point, but it’s essential to allow the soil to become a bit more neutral at this juncture, as an excess of coffee grounds can harm the shrub.
An Excess of Coffee Grounds Can Harm Hydrangeas
Hydrangeas do great in acidic soil, but too much acid can harm the shrub. If your soil’s pH falls below 5.0, you may notice smaller leaves, smaller blossoms, and even yellowing leaves. Too much acid will
- Harm a hydrangea’s ability to absorb nutrition
- Can harm a hydrangea’s cellular health
- Make the environment too acidic for beneficial earthworms and microbes
- Cause the surrounding ground to acquire a sour or strong odor
Keeping your soil at 5.0 or above will be important to ensure that your hydrangea is growing at its best, and looking lovely, so keep an eye on pH levels weekly.
It’s also important to allow the soil to become a bit more neutral as autumn approaches, as an excess in acidity could cause the hydrangea to bloom out of season and harm the plant. For this reason, ceasing coffee treatments in late August is ideal. Allowing your hydrangea to hibernate and wind down for the winter will keep it healthier year-round.
Besides soil concerns and coffee treatments, how else can you care for your hydrangea shrub?
How Else Can I Care for My Hydrangea?
Hydrangeas are relatively hearty and tough shrubs and don’t require much supervision to thrive well. However, they do love sunshine, so make sure they’re planted in a sunny, open area where they’ll get full sun for at least half the day.
Hydrangeas also love water. They’ll appreciate a healthy, prolonged watering once a week, especially in the early morning. They’ll also do well with mulch to lock moisture into the ground and allow the shrub to take full advantage of all rain or garden hose water.
Removing faded blooms will help your hydrangea redirect energy to grow leaves and flowers. You can also lightly prune your hydrangea before the growing season to give the plant a more rounded, healthy shape and remove dead branches or twigs.
Failure to prune your hydrangea will result in your shrub resembling more of a tree, with smaller and more scattered blossoms and a less beautiful appearance. Keeping it a bit lower in height will also help you manage the shrub easily and keep blossoms at a visually enjoyable eye level.
They also need well-drained soil, and coffee grounds can help break up the soil a bit and improve drainage. These same coffee grounds are also great for composting and can help enrich soil all over your property.
Coffee Grounds Can Be Composted
One of the best things about coffee grounds is that they make fantastic compost. Add them to your compost heap for a healthy, rich mix that can benefit not only hydrangeas in the early growing season but also crops and flowers.
Coffee grounds are a “green” composting material, despite their dark brown or black color. This is because coffee grounds add nitrogen to the soil and break down quickly. Other examples of “green” composting materials include fruit and vegetable peels, grass clippings, and eggshells.
“Brown” compost, on the other hand, tends to break down slower and adds carbon to the soil. Brown composting items include wood chips, bark, sawdust, dry or dead leaves, and hay.
A healthy compost pile has about a 50/50 ratio of both and is well-mixed to help items decompose and nourish soil quickly. This compost can help feed your entire garden and is excellent for vegetables, flowers, shrubs, and fruit trees.
Apart from its use as a fantastic composting agent, are there other ways to use coffee grounds around the home and garden?
Check out: Plants That Don’t Like Coffee Grounds
Are There Other Uses for Coffee Grounds?
Coffee grounds have a variety of other uses around the home and garden. For example, use them to make inexpensive fuel for your wood-burning stove or fireplace. This can greatly help in winter, or if gas prices surge, alternative heat sources would benefit you more.
Raw, ground coffee can also be used to absorb odors and moisture in a fridge, small pantry, or musty spaces. Use it to help reduce odors in a car or van, as well as to freshen up the air in a restroom.
Burning dried coffee grounds can also be a great way to help repel insects during the hot summer months. These grounds can also be sprinkled on a small fire for a similar effect. It’ll smell great and can help naturally repel mosquitos and gnats.
Hydrangea bushes thrive at a pH level of between 5.0 and 6.0 and can greatly benefit from coffee grounds. Sprinkle raw grounds near the base of your hydrangea shrub and water them into the soil bi-weekly through spring and summer, or water with coffee grounds-infused water weekly.
While coffee grounds can help encourage healthy, blue blossoms in hydrangea bushes, cease coffee ground treatments if the soil pH level drops below 5.3 or if you notice the hydrangea struggling. It is also important to cease treatments beyond late August, as your hydrangea will need time to wind down for the winter hibernation season.
You can also use compost infused with coffee grounds on your hydrangea early in the growing season and throughout your garden. Coffee grounds are also excellent as makeshift fuel, a natural insect repellent when burnt outdoors, and as an odor and moisture-absorbent material around the home.