Used coffee grounds can be repurposed as fertilizer for roses, but when, how much and how you apply this home-made fertilizer can be the difference between a thriving rose and one that you may accidentally damage.
Coffee grounds are a good fertilizer for roses. They provides essential nutrients that fortify the plant’s growth and improve the quality of the soil.
If you’re an avid coffee drinker looking to reuse coffee grounds, read my quick summary below on why coffee grounds are beneficial to roses, when and how to use coffee grounds, and what are some caveats you should know about.
Coffee Grounds Benefits on Roses
Coffee grounds added to the soil of roses have the following benefits:
- Contain nitrogen that’s essential for rose cane, stem and leaf growth
- Contain trace amounts of phosphorus, potassium and copper, all beneficial to plant growth
- Improve soil drainage and organic matter content
- Improve the soil ecosystem via worms that can feed on it and help aerate the soil and improve soil structure
- Ensure optimal soil acidity
Therefore, coffee grounds can act as a cheap, readily available fertilizer for your roses that will set off a ripple effect of other beneficial effects that can be seen in changes to the quality of the soil.
But just because coffee grounds are good, it doesn’t mean you should apply them liberally to the soil. You also need to understand when and how to apply coffee grounds to avoid any detrimental effects and maximize benefits.
When to Fertilize Roses with Coffee Grounds?
The main nutrient that coffee grounds provide to roses is nitrogen. As an essential nutrient for leaf growth and stem development, feeding nitrogen to your rose will promote soft leaf growth.
The season in which your rose may require a surplus of nitrogen is at the beginning of the growing season, which is set off by the months of April or May as soon as the plant comes out of its winter dormancy.
You can apply coffee grounds during spring through early fall. After mid-August, hold off on feeding your roses with coffee grounds to prevent new growths from dying at the first sign of frost. Frost-damaged growths should be pruned.
How to Use Coffee Grounds on Roses?
As with any commercially available fertilizer, coffee grounds should also be used in moderation to prevent any adverse effects.
If you’re curious about the harmful effects of coffee grounds on roses, you can read about them in the next section of this article.
In my experience coffee grounds are best used on roses (or even on houseplants and other garden plants) in a composted form rather than right after being brewed.
Composting coffee grounds will further reduce caffeine content, which isn’t ideal for plants and that may even stunt the growth of some plants and further reduce acidity levels.
If you’re using coffee grounds without composting, here are some good rules to follow to reduce any harmful effects:
- Sprinkle coffee grounds around the soil of the rose without putting the coffee grounds close to the stem. Distribute no more than 2 cups of coffee ground around the soil, then water in with 2 gallons of water.
- Alternatively mix in 2 cups of coffee grounds into 2 gallons of water in a watering can, and water around the soil
It’s important to use coffee grounds in moderation. It’s not necessary to work the grounds into the soil. Disturbing the soil around the rose may have unwanted consequences as disturbing the roots while digging the ground.
If you do this at the beginning of the growing season, your rose will have the needed nitrogen boost to grow new stems and leaves. You only need to do this once at the growing season.
While these methods are fine and the risks of overfertilizing aren’t big, I still encourage using coffee grounds in a composted version.
By adding coffee grounds to your compost heap, you’ll create a mulch that has just the right balance of nitrogen and carbon.
Use it to add a layer of compost around your roses, which will inhibit weed growth, improve drainage and help with the structure of the soil.
Can Too Much Coffee Ground Harm Roses?
The reason and repeatedly emphasized the need to use coffee grounds in moderation is because too much nitrogen will cause root burn in your roses.
This rule is the same for any other fertilizer you’re using. An abundance of nutrients will cause mineral build-up and lead to toxicity.
To minimize this risk, I simply compost coffee grounds first for that balanced combination of nitrogen and carbon that’s just better for my roses.
Do Coffee Grounds Help Get Rid of Ants on Roses?
I’ve heard people using coffee grounds to get rid of ants in their gardens. While ants are indeed deterred by coffee grounds, the effect is not permanent.
You’d need to reapply coffee grounds again and again to keep ants off your roses, especially that coffee grounds work best against ants when the grounds are still wet.
As we’ve established, adding too much coffee to your roses will cause root burn, so reapplying coffee grounds can lead to a surplus of nitrogen you don’t want.
But ants aren’t as harmful to your plants as you may think they are. In fact, they can have a beneficial effect on your garden. They can collect insects, aerate the soil, improve soil quality via their excrements, etc.
Coffee grounds can be put to good use in your garden, so next time you’re done with your coffee and you’re about to throw out the grounds, why not add it to your compost heap and use it on your roses?
Because nitrogen is the main nutrient in coffee grounds, be careful with the amount you’re adding to the soil if you’re using coffee grounds without composting first.
Apply only in the growing season (it’s best applied once in early spring) and remember that coffee grounds don’t provide complete nutrition to your roses and it doesn’t replace a normal fertilizing regimen.