Why Does My Periwinkle Not Flower?


Blooming mixed colored periwinkles

Caring for plant life is enjoyable for many, and undoubtedly supporting flourishing greenery affords many benefits for the environment’s overall health as well as making any indoor or outdoor environment look better. But, promoting each plant’s health can be perplexing considering so many influential aspects and traits of various plant species. Take the periwinkle as an example. Many people encounter problems when growing periwinkle and find it difficult to get the plant to bloom. Why will a periwinkle not flower?

The most likely cause for periwinkles not flowering is insufficient nutrients in the soil and/or a lack of water getting to the roots. Inadequate sun and too much shade exposure, as well as unsuitable weather conditions, can also affect the blooming of a periwinkle. A less common cause for poor blooms or no flowers can be resource deprivation when a periwinkle is placed too close to neighboring plants.

While encouraging flowers’ production in a periwinkle can be perplexing, most solutions are easy and straightforward relying only on overall good care and routines. Join us as we discuss why your periwinkles may not be flowering and what you can do about it as I outline how you can go about forming a thorough care plan to encourage blooming.

Why your periwinkle isn’t flowering

The periwinkle, formally known as the Catharanthus or Vinca Minor, belongs to the dogbane family and is a versatile plant since it can grow in various areas and zones. Periwinkles are relatively robust flowering plants that can easily grow outdoors in containers or directly in the garden soil. They also make beautiful potted indoor plants.

Periwinkles form broadleaf foliage and colorful flowers when their health is maintained. This plant grows so steadily that it’s commonly used as ground cover. The flowers of a periwinkle can range from a soft pink to a the stunning pastel purple and lavender blue that lends its name to the color.

Although the plant species is relatively tough, periwinkles are not immune to problems. A periwinkle that is experiencing difficulties may not produce any flowers at all, or it may produce flowers in low quantities and with poor coloring. In other cases you can be easily fooled that there is any problem with the plant as the irs health can seem fairly adequate because it continues to produce bright, green, and shiny foliage even though there is a lack of bloom.

However, factors such as the health of the vines and leaves on closer inspection will usually give insight into the potential reasons for the plant’s inability to bloom. Let’s take a look at some of those reasons now and their solutions.

Insufficient soil nutrient content

As I already stated periwinkles are pretty hardy plants so poor soil nutrition will not kill it. The periwinkle can survive in poorly nourished soil but will likely hold back on blooming too preserve the limited resources it has access to.

The roots’ nutrition supply plays a significant role in the plant’s functions as a lack of nutrition will affect the overall health of the plant and stop flowering.

Periwinkle plants generally skip on blooming and reserve their energy to maintain vital components such as roots, stems, and foliage when there isn’t enough nutrition to go around.

Although poor nutrient content on the soil is the most likely cause, compacted soil can also be to blame. Compacted soil can prevent water from reaching the roots and the lack of water can mean a lack of nutrients reaching the outer parts of the plant.

Inadequate watering routines

Watering is essential for producing flowers since plants will become stressed if they do not have sufficient water access.

A periwinkle plant must be watered sufficiently that the water reaches the roots to promote optimum health (like any plant). Obviously the most likely cause is a poor watering routine but it is not the only cause.

Again, you may be watering your plant adequately but the water is not getting through to the roots due to compacted soil.

Quick inspection of the soil surrounding your plant should show you if the soil is compacted. Compacted soil is something that many indoor plant owners do not even consider even though they are more likely to suffer from this if their soil has not been changed for some time. A buildup of old roots and new roots can soon make the soil so compacted that it is difficult to even get a garden fork through the top layers.

To check your soil for compacting, including potted periwinkles, take a handheld garden fork and gently lift the soil. Be careful not to dig too deep as you don;t want to cause any damage to the roots. If you find it relatively easy to turn the soil then your soil is fine but if you have to dig with real effort and find it difficult to lift the soil without it coming out in large clumps then your soil is compacted and will need aerated to allow water to penetrate to deeper levels where it will reach the roots which will carry hydration and nutrients to all areas of the plant.

Improper exposure to sunlight

All plants need the appropriate amount of exposure to sunlight to produce healthy flowers. Although periwinkles grow well as ground cover in semi-shade they are not a shade plant and will grow best when they have a healthy amount of access to sunlight. In fact they can even be grown in areas that get full sun (though this is not really ideal).

Periwinkles may not bloom at all if they are grown in areas that are too shady or too cool. Problems with a lack of bloom on periwinkles is particularly common in colder climates and in areas that do not get sunny weather but are constantly overcast.

Since this plant species is a climber, periwinkles may even begin climbing to higher points to access sunlight if placed in too much shade.

Check out your climate zone here if you are unsure if periwinkle is the best choice for your area.

Spacing and neighboring plants

The spacing of plants and nutrition deprivation is mostly an outdoor problem that occur with garden plants – but not always. If you place multiple plants in the same container or a raised bed then you can encounter this problem.

If the periwinkle is planted within the root zone of neighboring plant life or trees, the water supply may be consumed by the surrounding greenery. This may result in dehydrated roots and dry surrounding soil, which will cause the plant to feel stressed.

It can also result in nutrient deprivation as the other plants use up the available resources before the periwinkle can feed. For example, if your periwinkle is planted within the root zone of cedars or conifers, the soil may contain fewer nutrients as they feed heavily.

How do you get periwinkles to bloom?

Ok so we know the potential problems. What are the solutions?

Most gardeners and enthusiasts can agree that when plants bloom and produce flowers, it’s an indication that they are happy and comfortable.

While the periwinkle plant can survive in most areas, and even go without sufficient water and nutrients for a time, it will start to show the signs of water, nutrient or sunlight deprivation by first refusing to flower.

How the periwinkle grows will differ depending on various factors. It is not difficult to care for, but there are a few specific things you need to ensure you do so you encourage your periwinkles to bloom.

Soil requirements

The soil requirements for periwinkle plants involve sandy, clay, or normal sand with a pH level classified as acidic, alkaline, or neutral.

These hardy, colorful plans can be grown in pots or directly in the ground, but the soil needs to be drained well for the plant to maintain optimum health and rid itself of waste effectively.

Periwinkles may not bloom if they receive less ter than they need but too much water around the roots will drown the plant or cayuse root rot leading to plant dehydration and nutrient deficiency.

Watering requirements

Periwinkles can withstand drier seasons when mature and healthy, but young periwinkles may suffer repercussions with insufficient water.

The soil should be kept moist but not saturated.  Moist soil allows the periwinkle to grow and produce lush green foliage and vibrant richly colored flowers, and so you need to ensure that your plants receive deep watering, which targets the roots’ water supply.

Aim to water your periwinkle when the top layer of soil starts to dry out. This may mean different watering routine for different people. Periwinkle planted in semi-shade in a cooler climate zone will require less watering than one that is placed in full sun in a warmer climatic zone. Likewise, an indoor potted plant will require more watering when indoor temperatures are kept high and water evaporation is more likely.

Use your own judgment. If the soil is starting to dry out give you periwinkle a nice long drink of water and ensure the soil remains moist but not soaked.

Sunlight exposure

Although periwinkles can survive in various lighting conditions such as deep shade, dry shade, you replacement of the plant may have multiple effects on how they grow over time.

Although it is possible to grow periwinkle in full sun, constant exposure to direct sunlight is not beneficial for this plant, and you may find that the foliage gets burnt. Apart from being aesthetically unpleasing this will also cause the plant stress.

It’s best to ensure periwinkle receive enough sunlight to promote the blooming process but not so much that it stresses the plant. This plant grows and blooms best in partial shade with indirect access to sunlight.

Ideal spacing and neighboring plants

The spacing of periwinkles will play a role in how they can grow over time. It is important to give the plant space.

Periwinkle plants should be spaced approximately one foot apart to fill the allocated area and be comfortable within the space. Even if this seems too far apart remember than when the plants bloom they will easily cover the whole area.

Although periwinkles can handle fairly close proximity each others they should not be planted too close to other plants since this may affect the soil’s nutrient and moisture content. And bear in mind that some plants are more heavily water and nutrient dependant than others. I always advise gardeners to check the feeding and watering requirements of plants that they plan to plant together to avoid future problems with water and nutrient deprivation.

Temperature and humidity requirements

Certain climatic factors can pose problems and cause stress for the periwinkle plant. Planting in a poor climate zone may cause a periwinkle to hold back on the production of flowers.

Despite how tough this plant species is, it can suffer within humid or overly wet climates. Too much humidity and heat will run the risk of the plant developing diseases and poses hazards for its overall health.

Likewise, just as the periwinkle doesn’t like too much heat, it also hates the cold. Periwinkles cannot withstand freezing temperatures below 50°F, and they will need to be sheltered in such conditions (see our guide to winter gardening).

The periwinkle plant grows well in warmer climates, around 65°F.

How do you fertilize periwinkles to ensure good blooms?

Although this plant can grow in poorly nourished soil, its growth and capacities for colorful flower blooms will be stunted.

Providing your periwinkle with fertilizer will give its overall health a massive boost, enabling it to spend more energy and resources for all plant growth including vibrant colorful blooms – not just the essential functions that it must concentrate on when it is deprived of nutrients.

Feeding your periwinkle will encourage the plant to produce brighter, stronger, shinier, and greener foliage while promoting the blooming process for healthy vibrant flowers.

What fertilizer for periwinkle plants is best?

Periwinkle plants will benefit from a fertilizer that is well balanced. Going for a fertilizer that contains phosphorus, potassium, and nitrogen in equal parts will have the greatest positive impact on the health and blooms of the periwinkle.

A good quality 10-10-10 fertilizer, like this one, is an excellent option for periwinkle plants, particularly for those plants that are are in soil without the organic matter sufficiently rich in nourishment. This is the best choice for indoor potted periwinkles.

How often should periwinkles be fertilized?

For the most beneficial outcomes, you should fertilize your periwinkles with suitable fertilizer once a month during the spring and also in blooming season. This will ensure that the plant benefits from the immediate added nutrition while also maintain nutrient levels for future use thus encouraging flower production in following blooming seasons.

Although it can be distressing and discouraging to witness your cherished plants struggle to produce flowers, as you have seen the causes are fairly common causes and relatively simple to resolve. If your periwinkles is not blooming when you expect it to so not ignore the situation. A lack of flowering on a periwinkle is more often than not the first sign that the plant is experiencing problems and taking action quickly can avoid more serious problems developing later.

Take action in time and you may even encourage new blooms pretty quickly without having to wait until the next blooming cycle.

To prevent future problems, always ensure that your periwinkle is growing in areas that have suitable weather conditions or that you offer the pant protection against possible adverse weather conditions while also ensuring the plant gets sufficient nutrition and water, and is exposed to a balance between sun and shade. Do this and you will enjoy vibrant colorful periwinkle blooms year on year.

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