With their showstopping appearance, Ranunculus asiaticus is a favorite for weddings and bouquets. This rose-like flower sometimes goes by the name Persian Buttercup, which reflects its native home in the Mediterranean. These intricate flowers are characterized by paper-thin petals that grow in tight clusters. A single flower can have between 100 to 130 petals!
Ranunculus are a popular cut flower as they are not just beautiful but long-lasting too. They can also be successfully grown in outdoor gardens in the right environment. A common issue that faces many aspiring Ranunculus gardeners is yellow leaves. Even if the flowers seem healthy, yellow leaves can signify deeper issues with your plant.
If your Ranunculus leaves are turning yellow, it is usually due to a lack of sunlight, overwatering, or a lack of nitrogen.
Let’s take a closer look at the problems that cause yellow leaves and how to remedy them!
Why Are Ranunculus Leaves Turning Yellow?
Sometimes leaves turning yellow can be a natural part of the growing process. But sometimes, they can indicate an issue with your plant. Look at the three most common reasons why Ranunculus leaves turn yellow.
Lack of Sunlight
Ranunculus flowers are native to the Mediterranean and thrive with lots of sunlight. If you’re trying to grow Ranunculus in a cooler climate, the lack of sun can cause issues.
Ranunculus needs a minimum of 6 hours of full sunlight a day. Make sure you plant bulbs in a sunny patch of your garden or leave potted plants on a south-facing patio. Although Ranunculus loves light, it’s important to ensure the temperature doesn’t rise above 60°F (15°C), or the leaves will curl from excessive heat.
Why does a lack of sun cause yellow leaves? Light is required for photosynthesis, and photosynthesis produces chlorophyll, which causes the green color of leaves. Lack of adequate sun will cause yellow or pale colored leaves and even prevent the Ranunculus from blooming.
Ranunculus prefer to grow in sandy, loamy soil that mimics their native Mediterranean environment. They can handle short periods of drought but prefer moist soil.
Issues can arise when your Ranunculus is housed in heavy soil or is watered too often. The soil can become waterlogged, which can cause the roots to rot. With rotten roots, the plant won’t be able to absorb essential nutrients, and the leaves turn yellow and wilt in response.
Lack of Nitrogen
Nitrogen is one of the three primary macronutrients plants need to live, the other two being phosphorus and potassium. Nitrogen helps plants repeatedly regenerate by making DNA, protein, and amino acids.
When plants experience a lack of nitrogen, they will begin to conserve as much as possible. This often means drawing energy and resources away from older leaves to conserve new leaves. This can lead to leaves turning yellow or white.
The first sign of a nitrogen deficiency is yellow tips on your plant’s leaves. If you see this, you should fertilize your Ranunculus with a diluted NPK fertilizer. This will also help your plants produce more blooms during the spring growing season.
How Hot is Too Hot for Ranunculus?
Although this plant likes sunshine, it cannot tolerate long periods of heat. At temperatures above 70°F (21°C), Ranunculus will go dormant and stop producing flowers.
If you live in a region with a hot climate, protect your Ranunculus by providing adequate shade throughout the day. A shade cloth can be a big help if you have outdoor garden beds with little shade. Remember that Ranunculus are annuals, so it’s natural for them to die off in the middle of summer once temperatures go above 80°F (26°C). If you notice wilting and yellow leaves at this time, this is all a natural part of its life cycle.
How Often Should I Water Ranunculus?
How often you need to water Ranunculus depends on how it’s being planted. Ranunculus planted in containers tend to need more water than those planted in gardens. This is because the pot can hold less water than a garden bed.
During the growing season, Ranunculus will need more water as it uses more energy to grow. Generally, water new young plants every 10-14 days. Once the plant grows flowers, you can switch to watering it once a week.
Should You Prune Ranunculus?
Ranunculus has a habit of growing tall and leggy if allowed. The best way to avoid this is to deadhead the plant to encourage more flowers to bloom.
Deadheading is the practice of trimming away dead or dying flowers. This makes way for fresh flowers and helps redirect the plant’s energy to produce new growth. The best way to deadhead Ranunculus is to cut the stem below the dying flower. You can do this as often as you need throughout the growing season to keep your plant healthy.
What To Do When Ranunculus Die?
Once the leaves have wilted completely at the end of the plant’s life cycle, you can save and reuse the Ranunculus corms for next spring.
Wait for the leaves to die, then dig up the plant’s corm. Make sure you clean the soil off and allow it to dry in the sun. Once the corms are completely free of moisture, you can place them in a plastic bag or a box and replant them next year. Sometimes, the Ranunculus corms will produce babies that you can use to grow even more plants!
Do Ranunculus Bloom More Than Once?
Ranunculus has a relatively short blooming season. It generally produces flowers starting anywhere from January to May. Once it blooms, it will produce blooms for about a month before dying back.
Although it’s a shame that such a beautiful flower has such a short blooming period, there are ways to extend it. As mentioned earlier, deadheading will help keep the plant’s energy focused on producing flowers. Since Ranunculus are a cool weather flowering plant, anything to ward off the heat will keep them happy. A room or area of your garden that has good airflow will help create a cooling effect.
A high-quality fertilizer will also help your Ranunculus produce more flowers for longer. You can fertilize your plant once a week during the growing season. Use a fertilizer with a high amount of phosphorus. Phosphorus helps a plant photosynthesize and produce energy to feed off of.
Common Ranunculus Problems
Although Ranunculus is quite a hardy plant, certain issues are typical for this species. Here are some other issues besides yellow leaves that you should look out for.
Powdery mildew is a common fungal infection that affects plants. It thrives on dry plants, which is why it tends to be attracted to the sun-loving Ranunculus. The first signs of powdery mildew are usually small white spots on the leaves. It grows quickly and can eventually cover the entire leaf. This prevents the sun from reaching the foliage, which can slow down the plant’s growth.
Mildew tends to grow faster in humid environments. So, the best way to avoid powdery mildew is to ensure your plant is housed in an area with good airflow.
Another issue to watch out for, especially with outdoor Ranunculus, is aphids. These tiny green bugs love to eat the sap that comes from Ranunculus stems. They are considered a pest because of their ability to spread disease while they feast.
The best solution to ward off aphids is to spray your Ranunculus with water and dish soap. The taste is enough to ward them off, but regular treatments may be needed throughout the spring to keep them at bay.
Ranunculus is an excellent choice of flower to plant in your spring garden. Their relatively short blooming season will give you plenty of beautiful flowers. To enjoy the full beauty of Ranunculus, you want to ensure the foliage stays just as healthy as the flower. As a sun-loving flower, Ranunculus leaves turn yellow when they get too much shade.
If your Ranunculus leaves are turning yellow, it is usually due to a lack of sunlight, overwatering, or a lack of nitrogen. Root rot from overwatering will also cause the leaves to lack the nutrients they need to produce color. If you’re not fertilizing your Ranunculus enough, yellow leaves may also indicate a lack of nitrogen.
Yellow leaves indicate stress, so always be on the lookout for this symptom to avoid long-term issues with your Ranunculus!