Sweet pea shrub, also known as milkwort, is scientifically referred to as Polygdala dalmatian and should not be confused with another flowering plant, the sweet pea, which belongs to the legumes family.
The sweet pea shrub is well-known to gardeners as a captivating shrub that makes a wonderful addition to any garden or landscape.
Native to South Africa, the name “dalmatian” reportedly originated from Dalmais, the name of a French gardener who first sowed the seeds of this shrub in 1839.
Due to its striking beauty as a flowering plant, it has been introduced to various regions and has gained popularity among horticulturists worldwide.
Physical Characteristics of Sweet Pea Shrub
Due to their compact size, sweet pea shrubs are favorites in smaller gardens and landscapes and look beautiful as border plants. They are a truly delightful sight on a fair morning, whether it’s sunny or cloudy.
1. Appearance
The first thing you’ll notice about sweet pea shrubs is that they are neat shrubs that aren’t too dense. Even without pruning them, they don’t dominate other plants in your garden.
2. Height and Spread
The height of the sweet pea shrub can go as high as five feet, depending on the variety and growing conditions.
Similar shrubs belonging to the same family can reach up to 12 feet, but with proper pruning and management, the height of the shrub should never be a cause for concern.
3. Leaves and Flowers
The shrub features lush, lance-shaped leaves that are deep green. They exhibit a narrow profile and grow in an alternating arrangement along the branches. These leaves possess a glossy texture and appearance.
As for the flowers, they tend to cluster along the stems and display distinctive keels and wings. These stunning blossoms come in a variety of vibrant and delicate hues, with white and purple being the most commonly observed colors.
Comparison With Other Similar Plants
Sweet pea shrubs shouldn’t be confused with other plants like the common sweet pea (Lathyrus odoratus) and the pea shrub (Caragana arborescens). Although the flowers may bear some similarities to the sweet pea, the flowers of the sweet pea shrub have no fragrance.
Compared to similar plants in the garden, the sweet pea shrub stands out in its sweet way. It doesn’t outgrow other plants, and it maintains its tidy appearance. It’s on the list of ornamentals that have received the Award of Garden Merit (AGM) from the Royal Horticultural Society.
Growing and Cultivation
Even though sweet pea shrubs don’t require too much looking after, you still need to consider these factors when taking care of these precious shrubs. Here’s what you need to know about growing and cultivating sweet pea shrubs:
1. Ideal Growing Conditions for Sweet Pea Shrub
Sweet pea shrubs are hardy enough to grow in USDA zone 9-11. They love to thrive in places with a Mediterranean or temperate climate.
They prefer full sun exposure but can also tolerate partial shade. However, if you want your sweet pea shrub to have plenty of flowers, it’s recommended to choose a spot where the shrub can receive 6-8 hours of sunlight.
2. Soil Requirements and pH Levels
Sweet pea shrubs love to grow in well-drained soil that’s rich in organic matter. The pH level can range from slightly acidic to neutral, between 6.0 to 7.0.
In addition, it’s necessary to include a mixture of compost or well-rotted manure in the soil to improve the growth and fertility of these shrubs.
3. Watering and Fertilization Needs
Sweet pea shrubs need to be watered every day, especially during the hot summer months from June to August. However, make sure the soil is not overly saturated with water, as this can lead to root rot.
Additionally, the shrubs will benefit from fertilization twice during the growing season using slow-release fertilizers. It’s important to follow the instructions properly, as excessive fertilization can lead to overgrowth of foliage at the expense of flowers.
4. Common Pests and Diseases and How to Prevent Them
Sweet pea shrubs don’t have major issues when it comes to annoying bugs, but the common pests usually found on these shrubs are aphids and whiteflies.
Aphids
These small, wingless insects are found on almost every plant in your garden. They cluster all over the plants, where they feed on their saps and grow in large numbers, which can lead to severe infestation of your plant.
How to prevent them:
- Inspect your shrub regularly for early signs of infestation.
- You can manually remove them by handpicking or scraping them off the branches.
- Use reflective mulch around the base of the shrub, as this confuses them and makes it difficult for them to find their host plant.
- Plant other bug-deterring plants with strong scents that aphids hate, like nasturtiums, garlic, or mint.
- Encourage beneficial insects like ladybugs, lacewings, and hoverflies by planting nectar-rich flowering plants.
- Use insecticidal soap or oil for severe infestations.
- Avoid overfertilizing the shrub, as aphids are attracted to nitrogen-rich plants.
Whiteflies
These insects resemble winged aphids and are usually found on the undersides of leaves. They don’t cluster like aphids, but they multiply quickly and feed on plant saps as well.
How to prevent them:
- Remove infested leaves or parts to prevent them from spreading to other parts.
- These insects thrive in moist environments, so avoid overwatering your shrub.
- Use yellow sticky traps, as they are attracted to bright colors.
- Place reflective mulch around the base of the shrub that can disorient them.
- For severe infestations, you can use insecticidal soap and oil as well.
5. Pruning and Shaping Techniques
There are various methods you can use to prune and shape the sweet pea shrub to enhance its health, form, and aesthetic look. Here are the following pruning and shaping techniques:
5.1 Choosing an Ideal Time to Prune
The sweet pea shrub ideally be pruned in late winter or early spring, right before the start of new growth. This enables the plant to recoup and develop new growth during the growing seasons.
5.2 Removing Dead or Damaged Branches
Look for dead or broken branches that affect the overall appeal of your shrub. You can easily spot those branches due to their absence of leaves and signs of decay.
Use well-kept, sharp pruning shears and cut them close to the main branch or trunk. By getting rid of these branches, you can make the shrub look healthier and guard against diseases and pests.
5.3 Thinning
Select the branches crossing other branches
and remove them. This method is recommended to provide greater airflow and light penetration throughout the shrub.
5.4 Controlling Size and Shape
While pruning is a good way of controlling the shrub’s growth and shape if it’s gotten too big, trimming the brand tips promotes branching and encourages new growth.
However, be careful not to overdo pruning and trimming to avoid stressing the shrub. Don’t remove more than one-third of the shrub’s total growth in a single pruning or trimming session.
5.5 Training and Shaping
It’s crucial to start this method early and constantly trim and shape the sweet pea shrub if you want to train it into a certain shape such as a standard or topiary form. Here’s a list for proper training and shaping:
- Choose a main branch as a central form and start working on them over time.
- Continue to prune and shape the shrub as it grows to keep the desired shape and remove competing branches.
- Keep a close eye on the plant’s development and modify the pruning as necessary while respecting the shrub’s natural form.
Uses of Sweet Pea Shrub
Sweet pea shrubs surprisingly have numerous uses. They’re not only popular in gardening but may also be used for medicinal purposes, as well as traditional and cultural practices.
Ornamental Uses in Landscaping and Gardening
Here are the following ornamental uses of sweet pea shrubs in landscaping and gardening:
1. Garden Borders and Hedges
Sweet pea shrubs can be used as a lovely design for borders and hedges in your garden. They’re suitable for delineating walkways, dividing different areas in the garden, or providing structure to the general appearance due to their thick growth and evergreen leaves.
2. Flowering Displays
Sweet pea shrubs bear clusters of vividly colored pink or purple showy flowers. Your garden will benefit from the burst of color and the visually striking blooms of this shrub.
To create a spectacular floral display, think about planting them in groups or blending them with other flowering plants.
3. Container Gardening
Sweet pea shrubs can be planted in container pots, making them a great display in a small patch on your lawn, balconies, and patios. They can serve as a wonderful addition due to their compact size.
However, keep in mind that these shrubs prefer well-draining soil and need a good amount of sunlight. Make sure not to overwater them but retain the right amount of moisture in the soil and place them in a location where they can benefit from ample sunlight.
4. Rock Gardens
Sweet pea shrubs are a great plant to include in your rock garden due to their modest growth and tolerance to hot places.
To create a stunning and low-maintenance landscape, plant them among rocks, landscaping stones, or other draught-tolerant plants.
5. Mixed Border and Cottage Gardens
Sweet pea shrubs can offer a charming touch to mixed borders or cottage gardens. Their vibrant flowers, along with other perennial or annual plants, create a lovely environment and atmosphere.
For a more inviting picture of your cottage garden, you can plant them with Tropicanna canna, purple queen bougainvillea, and San Diego red hibiscus.
6. Attracting Pollinators
If you’re the type of person who loves to see your garden populated with pollinators such as bees and butterflies, sweet pea shrubs can attract these welcome insects thanks to their blossoms.
This is a great way to promote the biodiversity of your outdoor space and contribute to the well-being of local pollinator populations.
7. Erosion Control
Sweet pea shrubs have a deep root system that can be used to prevent soil erosion from wind and water runoff.
Additionally, the shrub’s foliage can serve as a ground cover, shielding the soil’s surface from direct impact.
Medicinal Uses of Sweet Pea Shrub
There have been studies conducted on the Polygala family that suggest potential medicinal properties. However, there’s no published research specifically regarding the use of Polygala dalmatian in medicine.
Nevertheless, other similar plants in the family, such as bitter milkwort (Polygala amara) and Polygala tenuifolia, are used in traditional medicine.
The root of bitter milkwort is used to treat airway problems, including cough and bronchitis. On the other hand, the root of Polygala tenuifolia is used in other countries, particularly in China, to treat insomnia and memory dysfunction.
Other Traditional and Cultural Uses
In some parts of Africa where these shrubs are common, the shrub may have been used by Cape Malays around the 1800s for washing their dead before burial by scraping off the bark and mixing it with water until frothed. However, this practice is no longer observed nowadays.
Final Thoughts
The sweet pea shrub is an adaptable and beautiful shrub that has a lot to offer your garden. For both inexperienced and seasoned gardeners, it’s one of the popular choices due to its vibrant blooms, capacity to draw pollinators, and simplicity of maintenance.
The sweet pea bush requires quite minimal upkeep in terms of care. It enjoys soil with good drainage, plenty of sunlight, and routine, moderate watering. The shrub can be kept in shape and given a healthy growth boost by pruning it after it blooms.
Think about integrating your sweet pea bush into different garden ideas to get the most out of it. The sweet pea shrub may add a touch of grace and beauty to any environment, whether it’s used as a border or hedge, in a container, or even in a rock garden.