Can You Plant Violas In Ericaceous Compost?

Can You Plant Violas In Ericaceous Compost

Reading Time: 5 minutes 🍃

Violas are a popular plant for planting outside in the garden or in containers for patios or to liven up the interior of your home. Can violas thrive in ericaceous compost, or is a standard compost or potting mix a better choice for these plants?

Ericaceous compost is not a requirement for growing violas, but the lower pH of the compost can benefit the viola plant, reducing the risk of fungal black root rot. The pH of the soil after adding ericaceous compost should be between 5.5 and 6.0 to provide ideal growing conditions for violas.

We will explore the benefits and considerations of planting violas in ericaceous compost and whether this should be an option you should consider when growing these plants.

Can Violas Grow In Ericaceous Compost?

Ericaceous compost is intended to acidify the soil in very specific gardening situations, enabling acid-loving plants to grow well.

Determining whether violas fall into this category and will grow with ericaceous compost in their growing medium requires understanding a little about the viola and what constitutes an ideal growing environment.

Soil pH is only part of the equation to give a plant everything it needs to grow strong and healthy and produce the floral display you expect.

Getting To Know Violas Before Planting In Ericaceous Compost

Violas are flowering plants that are part of the Violaceae family, known for their delicate, cheerful blooms and vibrant colors ranging from purple, pink, and yellow to white. 

Violas are hardy, versatile plants that can be grown as perennials or annuals, depending on the variety. They have many uses, from brightening garden beds and borders to adding color to patio pots and window boxes.

There are several varieties of violas to choose from, including the common garden viola or Viola x wittrockiana, sometimes called a pansy, a hybrid plant that produces larger blooms and is commonly grown as an annual. 

Other popular varieties include the Viola tricolor var. hortensis, a larger, more robust plant with bigger blooms, and the horned violet (Viola cornuta), a hardy perennial that produces smaller, dainty flowers.

Violas are relatively easy to grow and care for, requiring well-draining soil, regular watering, and moderate sunlight. 

They are also quite tolerant of cooler temperatures, making them a great choice for spring or fall flowering plants for gardeners in regions with mild climates. Violas are a beautiful addition to any garden with their bright, cheerful blooms and low maintenance requirements.

Check out: Ericaceous Compost for Pansies

What Soil pH Is Best For Growing Violas?

Violas prefer slightly acidic soil with a pH range of 5.5 to 6.0. They can tolerate a slightly higher pH of up to 6.5, but soil with a higher pH risks a fungal root infection called black root rot that can kill the plant.

Besides the susceptibility to fungal infection, the soil is too alkaline at higher pH levels, which can cause yellowing of the leaves, poor growth, and other symptoms of nutrient deficiencies.

The pH of the soil or growing medium affects the availability of soil nutrients to the plant roots. Soil with a pH level that is too high or too low can lead to nutrient deficiencies or toxicities. Therefore, ensuring the soil pH is within the ideal range for growing violas is important.

If you plan to plant violas in ericaceous compost, it is important to note that this soil type is specifically formulated for acid-loving plants. 

Violas require slightly acidic soil, which means that planting them in ericaceous compost can provide a slightly acidic environment in which they will thrive, but it also means that you can make the soil too acidic.

Risks Of Planting Violas In Ericaceous Compost

Ericaceous compost provides a slightly acidic environment where violas can thrive, leading to improved growth, stronger root development, and abundant flowering.

However, there are risks involved with planting these plants in ericaceous compost.

  • Making the soil too acidic. If you add too much ericaceous compost, the soil pH could be lowered too much, negatively affecting the plant’s ability to draw nutrients from the soil or burn the plant’s roots.
  • Not using enough ericaceous compost. If you use too little ericaceous compost, the effect on the soil pH will be negligible, and you will simply be wasting an expensive resource.
  • Using old ericaceous compost. Don’t use ericaceous compost that has been sitting around for a long time in your garden shed. Ericaceous compost loses its acidity over time and eventually has the same pH as standard compost, negating its pH amendment ability.

It is never a good idea to guesstimate pH levels when using ericaceous compost. It is very easy to miss-calculate quantities and over or under-adjust the soil pH.

Always use a good quality soil pH meter to accurately establish the soil pH to get the best results working with ericaceous compost.

How To Plant Violas In Ericaceous Compost

When planting violas in ericaceous compost, there are several steps you should follow to ensure their success.

It is best to prepare the growing medium well in advance to give it time to settle and allow you to monitor the final pH to ensure it is within the ideal tolerance range for the violas.

Mix the growing medium separately before planting, whether to grow the violas in the ground or in a container. You can use the mixture in the hole you dig to plant the flowers or fill the container with the growing medium before planting.

To create the growing medium, mix a premium potting mix with ericaceous compost in the ratio of 60% standard potting mix, 20% perlite, 10% ericaceous compost, and 10% sand. Mix the ingredients thoroughly and add water to dampen the mixture. 

Let the grow medium stand for 24 to 48 hours and test the pH with a suitable soil pH tester to check the levels. To lower the pH further, add another t2o handfuls of ericaceous compost and repeat the process to test the pH.

When the pH is correct, you are ready to plant the violas in their container or in the ground, using your mixture as the growing medium.

The following steps can be followed to complete the planting process.

  • Choose a suitable container. Violas can be planted directly in the ground or in containers, such as pots or hanging baskets. If planting in containers, ensure they have adequate drainage holes to prevent waterlogging.
  • Fill the container with your growing medium. Fill the container with fresh ericaceous adjusted compost, leaving a few centimeters of space at the top.
  • Plant the violas. Dig a small hole in the center of the container and gently remove the viola from its pot. Place the viola plant in the hole and backfill it with your compost mix, firming the soil around the base of the plant.
  • Water thoroughly. Water the viola thoroughly, ensuring that the soil is evenly moist. Avoid over-watering, as violas do not like wet or waterlogged soil.
  • Position the container. Position the container in a location that receives partial sunlight or light shade. Violas prefer cooler temperatures and do not like direct sunlight or hot, dry conditions.
  • Maintain the plants. Once planted, ensure the violas receive regular watering and occasional feeding with a balanced fertilizer. Deadhead spent blooms on the viola regularly to encourage new growth and prolong the flowering period.

You should periodically check the pH level in the container or around the plant in the ground to determine whether the soil pH is still within the optimal range or whether more ericaceous compost should be added to lower the pH.


Violas can be planted in ericaceous compost, but it is not essential. While violas prefer slightly acidic soil, they are less acid-loving than plants like azaleas or heather, which require ericaceous compost. However, planting violas in ericaceous compost can provide several benefits, such as improved growth, stronger root development, and abundant flowering.

When planting violas in ericaceous compost, it is important to ensure that the final pH of the growing medium is within the pH tolerance range of violas, which is 5.5 to 6.0.


Was this article helpful?

Team Leafy

Hi! Thanks for reading our article, we hope you enjoyed it and helps make your garden grow greener. If you found this article helpful, please share it with a friend and spread the joy. Plant small. Grow big!

Recent Posts