Whenever we go for fertilizer, we tend, most of the time, to buy the one that will provide as much nitrogen to our crops as possible. This is primarily because nitrogen is vital for the development of these crops and is the main constituent of chlorophyll, maintaining a balance in the process of photosynthesis.
One surprising product that is high in nitrogen and could function as a substitute in that respect is coffee grounds. Their primary available nutrient is nitrogen, necessary for healthy roses. The nitrogen is required in large amounts for stimulating the growth and development of new leaves, stem and cane growth. This article focuses on the relationship between coffee grounds and roses.
Do Roses Like Coffee Grounds?
Very much! There are several reasons why roses love coffee grounds and are listed below:
1. Providing Nitrogen
The primary available nutrient in coffee grounds is nitrogen, and along with phosphate and potash, nitrogen is the most important nutrient for healthy roses in the growing season and is required in large amounts as it stimulates new leaf, stem and cane growth.
As it so happens, coffee grounds are a welcome and much need hit of nitrogen when applied in the spring for new growth at the start of the growing season and to ensure a more healthy, disease resistance rose.
2. Providing Other Crucial Nutrients
Whilst coffee grounds are primarily valued by rose growers for their higher nitrogen content, they also contain other essential minerals such as phosphorus, potassium and copper, all of which will improve the health of the soil and are valuable nutrients for roses
3. Balancing the Soil’s pH
Roses also love the dose of coffee grounds as it ensures the right soil acidity. Roses grow best when the soil acidity is in the range of 6 to 6.8 on the pH scale, with a pH of 6.5 being optimal.
Used coffee grounds do differ in acidity depending on the variety of bean used, however, they are generally pH neutral to slightly acidic once decomposed which is perfect for fertilizing roses. However, it is crucial to test the pH of your soil first before adding coffee grounds for this purpose, to ensure your results are optimal for roses.
Coffee grounds are also beneficial for adding to your compost heap as it decomposes quickly and it can add valuable fertile material to be used as mulch for your roses and other plants in your garden during the growing season. An organic mulch such as coffee grounds is great at absorbing water so the roots of your rose can draw upon the stored moisture when the need to.
5. The Activities of Worms
Coffee grounds happen to be a favorite food of your local worm population. This will benefit the roses as worms effectively aerate compact soil which improves the soil structure and drainage.
The Department of Primary Industries in New South Wales, Australia, argues that soil with a high amount of worm activity will drain 10 times faster than an area with no worms. Worms feed on the coffee grounds and the resulting worm casts, concentrate the valuable nutrients and minerals which increases nutrient availability to the roots of your rose from the surrounding soil.
The tunnels and casts that the worms leave behind also allow the roots of your roses to penetrate deeper into the soil so that the plant has greater stability, and has access to moisture and nutrients for a healthier and more drought-resistant rose
6. Warding off annoying pests and pets
Coffee grounds, even leftover grinds can also be used for gardening as they help keep the unwanted pests out of the garden. The grounds, therefore, serve as an alternative to pesticides or insecticides which are full of chemicals.
A study by Nature, the journal which studies the natural world, found slugs and snails died after being sprayed with caffeine, although the amount of caffeine has to be a bit high. In addition to warding off pests, coffee grounds can also keep the cats away from your garden and away from your roses.
Cats can become destructive and messy by digging up your plants while scavenging for food. Adding strong-smelling substances, such as orange, pepper, eucalyptus and even coffee grounds can your feline friends off from visiting your crops.
How Do You Use Coffee Grounds on Roses?
The main point to remember here is moderation. In as much as coffee grounds are a viable source of nitrogen to roses, they should be used in moderation and not too much.
Coffee grounds contain a particularly high concentration of nitrogen and too much of the nitrogen can actually burn the roots of roses and other plants. Regardless, there are several effective ways to help your roses benefit from coffee grounds:
1. Distribute around each rose plant
Distribute half a pound of coffee grounds around each mature rose plant and water in with 2 gallons of water or a whole watering can. You will be sprinkling 2 cups or 500g around the surrounding soil of rose plants, thereby increasing the soil’s nitrogen content without harming the roots.
There is no need to dig the grounds into the soil as this could disturb the roots and surrounding soil structure which is why it is better to water in. Additionally, since worms love coffee grounds they will do all the hard work for you by pulling it down and working it into the earth.
As they digest the coffee grounds they will produce worm casts which are in a form that will be more readily available to the plant to uptake. You only need to do this once at the start of the growing season. If you fertilize your soil too late then this will encourage your rose plant to put on new delicate leaf growth late in the season which will be destroyed in the first frost of winter.
2. Mixing the coffee grounds in the water
You can also mix half a pound of coffee grounds in a 2 gallon (9 liters) water can. You will then water the surrounding soil of each of your roses, ensuring an even distribution of nutrients to the soil and also saving you the job of watering again.
Place the coffee grounds into the watering can first and then pour in the water to have it evenly mixed. Like in the method above, it is important to do this at the start of the growing season and not towards the end of summer as the hit of nutrients could encourage late season growth which will get immediately damaged in the first frost of winter.
Also do not exceed half a pound of coffee grounds diluted into your 2 gallons (9 liters) around each plant, to avoid suffering the side effects of an excessive concentration of nitrogen.
3. Composting the coffee grounds first
Adding coffee grounds to your compost will ensure that there is an appropriate mix of nitrogen and carbon in your mulch. Apply a layer of compost around roses, to suppress weed growth, improve the structure of the soil and increase drainage.
What’s more, is that an organic mulch such as coffee grounds is great at absorbing water so the roots of your rose can draw upon the stored moisture when they need to. Compost mulch is best applied around your roses at the start of spring as this is the peak time that weeds will attempt to grow and compete for resources with roses.
There is no need to dig the mulch into the soil as this could damage the roots and interfere with the established soil ecology and structure. Instead, distribute the mulch around the roses around 1-2 inches deep and let the worms and rain work the nutrients into the soil. Finally, avoid piling mulch around the stem of the rose as it could cause the stem to rot; an inch deep radius around the stem is enough to have the roses thriving.
How Often Should You Put Coffee Grounds on Roses?
You only need to do this once, at the beginning of the growing season. Regardless of the method you choose, you only need to do it once, during the spring. If you do this towards the end of the summer, the nutrients will likely encourage the late growth of the roses, meaning they will definitely be destroyed by the first frost of winter.
If you apply any nitrogen-based fertilizer after the middle of August, the new growth will likely turn black and die in the first frost. The start of the spring is also when most weeds will attempt to grow and compete for resources with roses. If you apply the coffee grounds through the composting method, not only will the compost provide the adequate nutrients required by the roses, but it will also kill the weeds and make your roses thrive.
What Nutrients Will Coffee Grounds Give to Your Roses?
As repeatedly mentioned, coffee grounds are valuable to roses among other plants because they offer quite high levels of nitrogen. To roses, nitrogen is very vital since it aids the plant during its growing season, as well as stimulating the development of new leaves, stems and cane growth. They can therefore serve as an abundant fertilizer, because of their ample nitrogen content.
However, coffee grounds should be used in moderation as if used in excess, they could burn the roots of your roses because of the particularly high nitrogen content. They should also be applied at the right time, to avoid stimulating new growth of the roses at the wrong time, like during the onset of winter, meaning the roses will be killed in that first frost.
Whilst coffee grounds are primarily valued by rose growers for their higher nitrogen content, they also contain other essential minerals. These minerals include phosphorus, potassium and copper, among other micronutrients.
All these nutrients are vital for roses as they improve soil health in addition to being valuable nutrients for roses. The quantity and proportions of these nutrients vary, but coffee grounds can be used as a slow-release fertilizer.
Which Plants Like Used Coffee Grounds?
While used coffee grounds are only slightly acidic, fresh and unbrewed coffee grounds have more acid. Most plants do not like the strongly acidic fresh coffee grounds, although the same cannot be said about acid-loving plants like hydrangeas, rhododendrons, azaleas, lily of the valley, blueberries, carrots, and radishes.
The plants that love used coffee grounds include hibiscus, iris, calla, marigold, sedge, bugbane, lily of the valley and crinum, among others.
On the flip side, some plants do not like coffee grounds at all and they include tomatoes, orchids, snake plant, yucca, lavender, century plant, rosemary, black-eyed Susan, succulents and cactus, among others.