Clematis is a heavy feeder with rather complex fertilizing patterns.
It’s not unusual for the plant to show signs of stress due to faulty fertilizers or not switching to the right NPK fertilizer at the right time. So what kind of fertilizer does clematis need?
What is the best fertilizer for clematis? No matter what fertilizer brand you use, you should feed your clematis with a 5-10-10 fertilizer (low nitrogen content) in the spring. Once the buds are about 2 inches long, alternate between low-nitrogen fertilizer and a balanced fertilizer with a 10-10-10 label. Apply once every four to six weeks.
Luckily the market is packed with many fertilizers that you can use to feed your clematis, keep it growing, and prolong the flowering season.
Here’s the lowdown of the best fertilizers for clematis and other tips to keep the vine blooming longer.
Best Fertilizer for Clematis
The best fertilizer for clematis is one that provides the right NPK ratio. As I mentioned, the perennial vine needs two types of fertilizer each year.
The first is a low-nitrogen fertilizer with a 5-10-10 ratio or similar. The second is a balanced fertilizer, such as 10-10-10.
The first encourages more flower bud growth while the second promotes more foliage growth and disease resistance.
Dubbed the blossom booster, Jack’s Classic is a low-nitrogen fertilizer with a higher concentration of phosphorus. It follows the classical ratio of 10-30-20, which is suitable for flowering plants.
You can use this fertilizer in the early spring and alternate it with a balanced fertilizer once the buds have grown. You can apply it to the soil before watering or use it as a foliar spray.
Epsoma Flower-tone is another fertilizer you can use with your clematis plants. Like Jack’s Classic, it too is low in nitrogen with a standard ratio of 3-4-5.
This means you cannot alternate it with Jack’s Classic, and you’ll also need a balanced fertilizer to provide your clematis with the perfect fertilizing schedule.
To apply it, spread it around the base of the plant without touching the vine or leaves. Water after application.
This fertilizer is ideal for spring application right before the flower buds of the clematis have appeared. Its NPK ratio is 4-8-4 with a focus on phosphorus.
It contains fish bone meal, kelp meal, and alfalfa meal among other ingredients. Apply 1.5 cups per vine in the spring, mix well with the soil, and then water vigorously.
This is a non-GMO fertilizer with an NPK ratio of 4-6-2. The low content of both nitrogen and potassium makes it a good fertilizer with which to start the spring application.
Apply it the same way you’d with other granular fertilizers. Make sure it doesn’t touch the vine or the leaves, and water the clematis thoroughly after each application.
This is the first fertilizer on the list with high nitrogen content. With an NPK ratio of 12-4-8, this fertilizer works best once the clematis flower buds have reached 2 inches long.
Alternate it with any one of the above low-nitrogen fertilizers once every 4 to 6 weeks. Apply 3/4 cup around the base of the heavy-feeding vine, and water immediately.
Osmocote is a balanced fertilizer with an NPK ratio of 14-14-14. That means it’s an ideal candidate to alternate with any of the above low-nitrogen fertilizers.
The granules are coated with resin to make the nutrients in the shell easier to absorb even in cold soil.
Apply 3 tablespoons for every 2 gallons of water. Alternate with a high-phosphorus, low-nitrogen fertilizer every 4 to 6 weeks.
Fertilizing Clematis: Quick Guide
To fertilize clematis, you’ll need two types of fertilizers. The first is a low-nitrogen, high-phosphorus fertilizer with an NPK ratio averaging 5-10-10 or something similar.
The second fertilizer is a balanced one with an NPK ratio such as 10-10-10.
How To Fertilize Clematis
You will need to start feeding clematis as soon as the weather warms up in the spring and before the first buds appear.
Use the low-nitrogen fertilizer once every 4 weeks. Follow the instructions on the package, and use the right dosage so as not to burn the vine.
Make sure the fertilizer doesn’t touch the vine or the leaves.
Once the buds have reached 2 inches long, you can alternate with a balanced fertilizer. Apply it every 4 to 6 weeks.
The nitrogen in the balanced fertilizer will improve the growth of the root ball, stems, and leaves. The phosphorus will give you plenty of blooms with brighter colors and long vase life.
When To Fertilize Clematis
The best time to start fertilizing clematis is before the first signs of flower buds. Apply a high-phosphorus fertilizer every 4 weeks.
When the buds are 2 inches long you can start using a balanced fertilizer along with the high-phosphorus, low-nitrogen fertilizer.
Apply this new schedule once every 4 to 6 weeks until the flowering season is over.
How To Make Clematis Bloom All Summer
Some clematis varieties tend to have a longer bloom season than others.
That, combined with proper care from pruning to feeding and watering, can ensure the clematis will bloom from the spring all the way to the fall.
Some hybrids like the new Sugar Sweet hybrids and the Montana cultivars are known for their long blooming season.
What’s a Good Homemade Fertilizer for Clematis?
The heavy-feeding clematis loves some alkaline fertilizer every now and then to improve its blooms.
Mix a quarter cup of ammonia into one gallon of water, and feed the vine before and during the bloom season.
This homemade fertilizer is no substitute for the other fertilizers I covered in the previous sections. It’s merely a supplement to give you brighter and bigger blooms.
Compost tea or worm casting tea are also good options to try.
Are Coffee Grounds Good for Clematis?
You can use coffee grounds as fertilizer for clematis. However, coffee grounds will increase the acidity of the soil. So don’t use it too much, especially if the soil is already too acidic.
Wrapping It Up
When fertilizing clematis, use a low-nitrogen 5-10-10 fertilizer from the early spring until the flower buds are 2 inches long.
Then alternate with a balanced 10-10-10 fertilizer for the rest of the growing season. Apply the fertilizer once every 4 to 6 weeks, and water immediately after each application.