Hydrangeas are a beloved flowering shrub known for their lush, colorful blooms that signify the height of summer Their mophead and lacecap flowers come in stunning hues of blue, purple, pink and white that can brighten up any garden But did you know that adding coffee grounds to the soil can take your hydrangea’s beauty to the next level?
Coffee grounds offer a range of benefits for hydrangeas. They provide essential nutrients, help adjust soil pH for optimal bloom colors, and improve moisture retention and soil structure By understanding when to incorporate coffee grounds into your hydrangea’s care routine, you can promote more vigorous growth and maximize the vibrancy of its flowers.
How Do Coffee Grounds Benefit Hydrangeas?
Coffee grounds positively influence several factors that determine your hydrangea’s health and performance. Here are some of the key benefits:
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Essential Nutrients: Coffee grounds contain nitrogen, phosphorus, potassium and other trace elements that hydrangeas need to grow strong and flower abundantly. The nitrogen in particular stimulates lush foliage growth.
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Soil pH Adjustment: Hydrangeas prefer slightly acidic soil with a pH between 5.5-6.5. Coffee grounds help lower pH in alkaline soils, promoting vibrant blooms. This effect is especially useful for changing bigleaf hydrangea flower color.
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Moisture Retention: Coffee grounds boost the soil’s ability to hold water. This helps keep hydrangea roots consistently hydrated.
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Improved Soil Structure: Coffee grounds aerate the soil and create spaces for increased root development. Well-structured soil enables better nutrient absorption.
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Weed Suppression: Applying coffee grounds as mulch forms a protective barrier that prevents weed growth around your hydrangeas.
When Should You Add Coffee Grounds to Hydrangeas?
Timing is crucial when adding coffee grounds to hydrangeas. Targeting the right growth stages maximizes their benefits for your plants.
Spring
Early spring is prime time to incorporate used coffee grounds into the soil around your hydrangeas. This provides a nutritional boost of nitrogen right when the plants begin active growth after winter dormancy. It helps promote lush leaf development, strong stems and abundant blooming in the coming months.
Aim to mix 1-2 cups of fresh grounds into the top 2-3 inches of soil near each hydrangea in early spring. Distribute them evenly around the plant’s drip line or spread in a ring 6-12 inches away from the base.
Fall
As growth starts slowing down in fall, hydrangeas can again benefit from another application of coffee grounds. Fall is the ideal time to improve soil structure and moisture retention in preparation for winter dormancy and next year’s growth.
Follow the same technique as spring, working 1-2 cups of used grounds into the topsoil around each plant. This helps provide nutrients that hydrangeas can store for next season while enhancing the soil’s properties.
Additional Applications
While spring and fall feedings are optimal, you can provide an extra nutritional boost any time during the growing season if your hydrangeas show signs of nutrient deficiencies. Yellowing leaves, stunted growth, and lackluster blooms are indicators that your plants could use more nitrogen and minerals. Mix in a bit more used coffee grounds to give them what they need.
Just be careful not to overdo it, as excessive grounds can accumulate salts that damage hydrangea roots. Monitor your plants and soil to adjust coffee applications as needed.
How to Apply Coffee Grounds to Hydrangeas
Used coffee grounds are easy to incorporate into your hydrangea care routine. Here are some simple methods:
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Mix into soil: Blend grounds into the top few inches of soil around each plant. This directly supplies nutrients and lowers pH.
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Top dress: Spread grounds in a 1⁄2 to 1 inch layer around the base of plants as mulch to provide slow-release nutrition as they break down.
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Add to compost: Include used grounds as you build your compost pile. Later mix this nutrient-rich compost into your garden beds.
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Prepare fertilizer: Combine coffee grounds with other organic materials to create a balanced homemade fertilizer mix.
No matter which technique you choose, always follow recommended ratios for best results. And be sure to reapply as needed during the key seasons mentioned above. With the right schedule, you’ll enjoy a healthy, robust hydrangea with maximum flower power.
Coffee Ground Cautions for Hydrangeas
While coffee grounds offer multiple benefits, a few precautions are prudent:
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Test soil pH regularly and adjust coffee applications accordingly to avoid excessive acidity.
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Prevent fungal issues by keeping grounds from directly contacting stems or leaves.
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Monitor salt content if using high volumes of grounds over time.
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Scatter additional grounds around plants showing nutrient deficiencies.
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Pair with compost or organic matter so nutrition remains balanced.
Troubleshooting Hydrangeas with Coffee Grounds
Here are some tips if you encounter issues after using coffee grounds on your hydrangeas:
Yellow leaves: Add more grounds to provide a nitrogen boost. Or reduce quantities if excessive salts accumulate.
Poor flowering: Lower pH may be limiting nutrient uptake. Do a soil test and adjust acidity with lime if needed.
Slow growth: Check that soil still drains well and aerate if compacted. Coffee grounds can sometimes retain too much moisture.
Fungal problems: Remove any grounds touching stems to prevent rot. Improve airflow and water at the base only.
Weeds emerging: Top dress with a fresh layer of grounds to suppress new weed growth through the summer.
Achieve Optimal Hydrangea Health with Coffee Grounds
While hydrangas are relatively low maintenance shrubs, taking some extra steps to care for them properly can make all the difference in their performance. Used coffee grounds are a simple, natural way to provide essential nutrients, adjust soil conditions and give your plants the conditions they need to really thrive and showcase their best blooms.
Pay attention to timing and technique when applying coffee grounds to maximize their benefits. With the right balance of soil nutrients and acidity provided by spent grounds, you’ll be rewarded with vibrant, lush hydrangeas that add truly spectacular color to your garden year after year.
Can coffee grounds be used to change the color of hydrangeas?
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. However, its best to use aluminum sulfate, a proven method for changing flower color.
Hydrangeas MenuTypes, color, pruning and more
The color of a hydrangea can change dramatically, and sometimes they even exhibit multiple colors on the same shrub. Lets Dance Lovable® bigleaf hydrangea. Photo by: Proven Winners.
Flower color can be changed only on specific species of hydrangea, mainly those related to H. macrophylla or H. serrata. The common thought is that flower color is related to the pH of the soil. However, as Michael Dirr explains in his book Hydrangeas for American Gardens, the color is not determined by the pH, per se, but the amount of aluminum a plant can access in the soil — which is determined by pH and phosphorus levels.
A lower pH allows aluminum to be soluble and absorbed by plants (unless phosphorus is high), and the flowers tend to be blue. A higher pH locks up the aluminum and the flowers tend to be pink. Shades of cream to green can also be seen when blooms first open, and tones can change as flowers age.
Tip: Find out your soils pH by using a 3-in-1 soil tester.
Here’s how you can adjust your soil to affect the bloom color:
- Soil pH below 6.5 = Blue
- Soil pH above 7.5 = Pink/purple
- Soil pH 6.5 to 7.5 (neutral) = Purple, or both blue & pink
- To make sepals bluer, add aluminum sulfate to soil and maintain low levels of phosphorous, moderate levels of nitrogen, and high levels of potassium.
- To make sepals pinker, add garden lime to soil plus maintain high levels of nitrogen and low levels of phosphorous.
- This should be done well in advance of flowering, in autumn and again in early spring. It may take a couple of years to see the full effect. Soil amendments take effect on the developing buds, not flowers that have already formed and bloomed.
Hydrangeas & Coffee Grounds
FAQ
Do you put coffee grounds on plants wet or dry soil?
“Please be aware that you CANNOT just throw wet coffee grounds down anywhere. They must be thoroughly dried first or they will definitely mold and rot. Don’t throw wet ones down in your garden, and certainly do NOT just plop them into your houseplants, unless you’re conducting a mold-growing experiment.
How to turn hydrangeas blue naturally?
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Soil Acidity is Key:Hydrangea flower color is determined by the soil’s pH level. Acidic soil (pH below 5.5) promotes blue blooms, while alkaline soil (pH above 7) leads to pink or red flowers.
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Natural Methods:
- Coffee Grounds: Sprinkle used coffee grounds around the base of the hydrangea plant and work them into the soil. Coffee grounds naturally increase soil acidity.
- Citrus Peels: Similar to coffee grounds, citrus peels can also help to acidify the soil.
- Pine Needles/Bark: These organic mulches break down slowly, releasing acids into the soil, which can help lower the pH.
- Apple Cider Vinegar: Dilute apple cider vinegar with water and apply it to the soil around the hydrangeas. This will gradually lower the pH.
- Coffee Grounds: Sprinkle used coffee grounds around the base of the hydrangea plant and work them into the soil. Coffee grounds naturally increase soil acidity.
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Chemical Methods:
- Aluminum Sulfate: This is a common and effective way to lower soil pH quickly. Follow the instructions on the product label for application.
- Elemental Sulfur: Another option for acidifying the soil, but it takes longer to work than aluminum sulfate.
- Aluminum Sulfate: This is a common and effective way to lower soil pH quickly. Follow the instructions on the product label for application.
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Important Considerations:
- Timing: Apply soil acidifiers in the early spring or fall, before the plant starts to grow or before the growing season ends.
- Patience: Changing soil pH takes time, so don’t expect immediate results. It may take a few seasons to see a noticeable change in flower color.
- Test Your Soil: Before making any changes, it’s a good idea to test your soil’s pH to determine how much acidifier you need.
- Don’t Overdo It: Adding too much acidifier can harm your plants, so follow the instructions on the product label carefully.
- Timing: Apply soil acidifiers in the early spring or fall, before the plant starts to grow or before the growing season ends.
How often should I add coffee grounds to my plants?
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Frequency:
- General Rule: Add coffee grounds to your plants once a week, or once every 7-10 days.
- Diluted Coffee: You can also use a diluted coffee solution, watering your plants with it once a week.
- Composting: Adding coffee grounds to your compost pile is also a good option, and you can then use the composted material as a soil amendment.
- General Rule: Add coffee grounds to your plants once a week, or once every 7-10 days.
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Benefits:
- Nutrient Rich: Coffee grounds are a good source of nitrogen and other nutrients that plants need.
- Soil Improvement: They can improve soil structure and water retention.
- Acid-Loving Plants: They can help acidify the soil, which is beneficial for plants like azaleas, blueberries, and rhododendrons.
- Pest Deterrent: Coffee grounds can also deter certain pests like slugs and snails.
- Nutrient Rich: Coffee grounds are a good source of nitrogen and other nutrients that plants need.
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Potential Issues:
- Over-Acidification: Overuse of coffee grounds can lead to excessive soil acidity, which can harm plants.
- Moisture Barrier: Coffee grounds can compact and create a moisture barrier on the soil surface, so it’s best to mix them in or use them in moderation.
- Caffeine: While caffeine in coffee grounds is not directly harmful to plants, it can suppress the growth of certain plants, especially seedlings.
- Over-Acidification: Overuse of coffee grounds can lead to excessive soil acidity, which can harm plants.
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Best Practices:
- Mix with Soil: Instead of directly applying coffee grounds to the soil, it’s best to mix them in or add them to your compost pile.
- Monitor Your Plants: Pay close attention to your plants’ health and adjust the frequency of coffee ground application accordingly.
- Consider Soil pH: If you have plants that prefer alkaline soil, avoid using coffee grounds directly or rinse them before adding them to the soil.
- Mix with Soil: Instead of directly applying coffee grounds to the soil, it’s best to mix them in or add them to your compost pile.