Coffee grounds have long been used as a soil conditioner for plants with varying degrees of success. Some plants don’t like it, but hydrangeas benefit from this soil amendment. Coffee grounds contain nitrogen, and they can increase soil acidity. Both are of interest to hydrangea plants. Adding used coffee grounds to the soil of plants can also improve the quality of the soil. Below we will explain how to fertilize hydrangeas with coffee grounds, what benefits you can expect, how often you should add them, whether they are suitable for hydrangea potted plants, and how to change hydrangea flower color with coffee grounds.
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Fertilizing hydrangeas with coffee grounds: advantages
Hydrangeas like slightly acidic soil, and coffee grounds can help change the pH of the soil so that it is less alkaline and more acidic. You can use a pH meter or soil test kit to determine the pH of the soil and make the necessary changes depending on the results you want. If you fertilize your hydrangeas with coffee grounds, you can also expect the following benefits:
- Improved soil quality by adding organic matter to the soil.
- Better moisture retention, which is good for hydrangeas
- Coffee grounds are rich in nitrogen and promote the development of stems, leaves and roots.
- When composted, coffee grounds can also be used to improve soil drainage.
- Coffee grounds can be beneficial to earthworms, which in turn help improve soil quality.
- You can use coffee grounds after brewing, but you can also throw them on a compost pile and use them in composted form. This will allow you to maximize the benefits.
When to observe the effects for the plants
The way you brew your coffee grounds can also affect the acidity of the grounds. With most brewing methods, a significant amount of acidity is washed out, and the coffee grounds retain only a residual amount of acidity. However, it can still affect the acidity of the soil, but the effects are only seen with repeated applications over time.
How often should you use the fertilizer
When composting coffee grounds, simply use them whenever you would otherwise add compost to the soil of your hydrangeas. Add the compost in the spring, at the beginning of the growing season, and sometimes even in mid-summer. Usually, adding compost 2-3 times a year is enough to keep your hydrangea plants happy. If you use coffee grounds without composting them first, you can add a few cups per week depending on the size of the shrub. However, you don’t need to overdo it. Too much coffee grounds can lead to excess nitrogen in the soil, which can cause plant development problems and even attract pests and insects.
Adding too much coffee can also change the pH balance of the soil and have other undesirable effects, such as retaining too much moisture and adding too much residual caffeine to the soil, which young plants may not like. If you have a pH meter, you can check the soil pH regularly to see if you are overdoing it or not. Generally, hydrangeas prefer soil with a pH between 6 and 6.5. Much also depends on the size of the shrub. A mature plant will not be negatively affected by a few cups of coffee grounds that you may sprinkle over the soil each week. As mentioned earlier, don’t overdo it with the coffee on young plants.
Can you use coffee grounds for potted hydrangeas.
Try to refrain from using coffee grounds on potted plants. There are at least two reasons for this. First, it can stink, especially if it’s damp. And hydrangeas like moist soil. Second, moist coffee grounds can be a breeding ground for bacteria and fungi, which I’m sure you want to avoid. Still, you can use coffee grounds for potted hydrangeas if you keep a few things in mind. Composted coffee grounds are better for potted plants because they reduce many of the problems associated with regular coffee grounds, such as odor, residual caffeine, too much acidity and too much moisture. Mixing potting soil with coffee grounds improves soil aeration and drainage. However, if you sprinkle coffee grounds over your hydrangeas’ potting soil from time to time, you won’t notice any drawbacks. Watch how your plants respond.
How to change the color of hydrangeas with coffee grounds
Add coffee grounds to the soil around your hydrangeas in late fall. Sprinkle it around your plants, but be sure to work it into the soil to avoid an unpleasant odor. You don’t need to do this process often – two to three times a year should be enough. How long does it take for hydrangeas to turn blue? If you pour the coffee grounds left over in the morning onto the hydrangea soil, the plants will not bloom blue by the afternoon. It will take some time – especially if you have brand new baby hydrangeas that may not bloom for a few years. It’s best to start adding coffee grounds to the soil months before they start blooming, preferably in late fall. You can repeat the process with your usual fertilization schedule.
The first step on the road to blue hydrangea is to select a variety that can produce blue flowers. Oakleaf hydrangea (Hydrangea quercifolia), Annabelle hydrangea (Hydrangea arborescens) and Peegee (Hydrangea paniculata ‘Grandiflora’) all bloom white and do not change hue regardless of soil pH. However, if you have French hydrangeas or Lacecaps (Hydrangea macrophylla normalis), you may have success!