Prunella vulgaris is known by many names, including the popular self-heal, which gives us a clue about this plant’s many medicinal uses. It’s an herbaceous plant and member of the mint family grown widely all over the northern hemisphere, and in some parts, it has become invasive.
It has many phytochemicals, making it relatively immune to pests and diseases. But it is also an important plant for its medicinal value as an anti-inflammatory, immune-boosting properties, and aid in digestion and overall health. Its botanical name, Prunella, is derived from a German word for diphtheria, as it was used in the past to cure this throat disease.
Whether you want to grow self-heal just as a pretty pollinator plant or for its medicinal value, this hardy plant is well worth the effort. It is also easy to propagate and has few pests.
Prunella vulgaris ‘Self Heal’ Overview
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What is Self-Heal?
Common to temperature climates, Prunella vulgaris is a garden plant but can also be found in woodlands, on roadsides, and in areas where nothing else much grows. It has a rich history of healing and has been used for centuries to soothe sore throats and treat other ailments.
Native Area
The plant’s native area covers all corners of the northern hemisphere. In the 1800s, it was introduced into other countries, like Australia and New Zealand, where it became invasive. It’s a common herb that can be controlled in a garden setting.
Characteristics
This herb has square stems and a creeping habit. The lanceolate shape and toothed edges form opposite each other on the stems. It looks similar to other herbs in the mint family and will grow to an average of 12” tall but sometimes up to two feet. Self-heal is self-seeding and can spread via runners to form a carpet, making it a good ground cover plant. Because of this ability to form a mat, it is often used to stabilize banks.
The flowers form on long stems and are delicate and tubular-shaped. They range in color from deep purple to shades of lavender. The flowers are pretty and sit in whorls clustered on the top of stems. Flowering time is usually summer, but that will also depend on the climate.
Planting
Sow seed directly into prepared beds in spring or late autumn. Cover the seeds lightly and water well to allow them to germinate. If you already have some in the garden, you can allow them to self-seed, but remember that they can become invasive and, in some cases, are classified as weeds. To ensure that the growth does not get out of control, they can be trimmed before they start going to seed.
Transplanting
Self-heal can also be transplanted into a new area if they have been dug up with enough of a root system. Move to a new area and water well to establish the transplants in a new clump. In this way, plants can be increased around the garden or moved into a more desirable position to flourish.
How to Grow
A few vital elements need consideration to get the best out of this interesting herb. Once you have these down, they are considered hardy herbs. Let’s discuss what they need to thrive:
Light
In temperate climates, it grows in full sun and will do okay in partial shade. However, in very hot climates, it’s best to give it some afternoon shade. For it to flower well, it’s best to situate it with at least four to six hours of sunlight daily.
Water
Self-heal prefers moist soil, but it must be well-draining. Waterlogged soil will cause issues with the roots, and root rot may be a factor. While the plants are being established, they need more water than once established, and then they are fairly drought-tolerant.
A layer of mulch two to three inches thick will help conserve water until they are established.
Soil
Although not too particular about soil type, they prefer well-draining soil that holds moisture and provides some nutrients. This means that loamy, friable soil is best. Drainage is the most important element so the soil does not become waterlogged. This herb prefers a slightly alkaline soil with a pH between 6.0 and 7.5. Add organic matter to any soil to increase the pH levels.
Temperature
As a temperate herb, it prefers mild summers and cool winters. The ideal temperature range for self-heal is 41-95°F (5-35°C). The USDA hardiness area for growing self-heal includes zones 4-9. If growing in the hotter zones, more shade is advisable to keep the herbs cooler.
Fertilizer
Self-heal is not too fussy about soil, but it’s always better to enrich the soil with added compost when planting most plants. It is not necessary to fertilize these plants, but if they look scraggly, they could use a boost. Feed them with a balanced organic slow-release fertilizer in spring. Look out for any yellowing leaves, which may indicate that they need a feeding injection.
Maintenance
Maintaining a good shape and not letting the herbs become invasive and take over other nearby plants is important. Trim back and shape after they have finished flowering. This will prevent them from going to seed and encourage more flowers. Prune again in late fall and early spring to shape.
If you don’t want the plant to self-seed, deadhead the flowers continuously. Also, remove any dead or damaged foliage on an ongoing basis.
Propagation
There are three ways to propagate these plants: sowing seed, dividing the underground rhizomes, and transplanting. We have discussed transplanting in this article, but we can expand on seed sowing and dividing:
Seed
Collect seeds from growing plants in the fall and winter when the seed heads have matured and are dry. Keep in the fridge before sowing.
Sow the seed directly into prepared beds in early spring or the fall. Prepare the soil with extra compost and rake to provide an even surface if needed. Sow the seed four to six inches deep and space (or thin out) six to nine inches apart. Cover with a thin layer of soil and water well. Keep the soil moist until the seeds have germinated in a few weeks, and then continue watering until they are well-established plants.
Division
Divide from established self-heals in early spring or in the fall when the plant shows signs of new growth or is completely dormant.
Dig up a clump carefully, trying to preserve the root system as much as possible. This can be done easily with two garden forks on opposite ends. Divide the clumps into sections with a good section of the roots attached.
Replant the divisions in new soil, spacing them six to nine inches apart so they can grow with good airflow and water well until they are established.
Common Problems
It has been discussed previously that due to the chemical compounds in this herb, they are avoided by many pests and diseases, which is a major bonus in any garden. Generally, the only thing that can go wrong is planting this herb in soil that does not drain well, and that can become waterlogged, resulting in root problems. To be complete, we have mentioned some pests and diseases to look out for here.
Pests
The common sap-sucking aphid may attack many plants, including self-heal. This pest is destructive in the garden but can be controlled using techniques like a fast stream of water, or resort to neem oil or insecticidal soap.
Diseases
Not much will harm self-heal, but be on the lookout for powdery mildew, a fungal disease that shows up as a white powder on the leaves. This is often found in areas with high humidity and overcrowding. Control by making sure there is enough space between plants and good airflow. Avoid irrigating plants overhead, and use drip irrigation or apply a product like neem oil. For herbs already infested, cut off any infected plants and destroy them. Do not add to compost heaps.
Root rot may occur if the plants are overwatered and become waterlogged. The roots will suffocate and become infected. The plants should be dug up, and the roots should be inspected for major infections. If they are too far gone, destroy or cut off the infected areas and replant them, ensuring they are in an area with good drainage. Adjust the watering schedule.
Frequently Asked Questions
Teas are made with leaves and stems and are used as anti-inflammatories for the stomach and intestines and for sore throats, among many other conditions. However, please consult a doctor before relying on any herbal medication.
In some regions, self-heal has been introduced and has become invasive. If the plant becomes invasive in a garden, it’s easy enough to control by pruning regularly and making sure the flowers don’t form seed. It will self-seed if allowed.
Yes, all the parts of the plant are edible and can be used in salads, soups, and stews. However, the tannins in the leaves can make them bitter.