The Carissa Boxwood Plant – A Comprehensive Guide to Growing
The Carissa boxwood, known by its scientific name Carissa macrocarpa, is one of the most popular plants to be used for landscaping by many homeowners and landscapers out there. What makes the Carissa boxwood shrub even more attractive is the fact that it requires little water, grows dense, and it’s also quite ornamental. This little green bush is increasingly becoming common in many landscapes across the world, and not just because it suits the minimalist style but also because it can be used for multiple purposes when it comes to landscape architecture. In this guide, we’ll take you through what you need to know about the Carissa boxwood plant and what makes it a great addition to your landscape.
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Origin and Characteristics of the Carissa Boxwood Plant
The Carissa boxwood is from south Africa where it is native to coastal areas and subtropical regions. It is part of the Apocinaceae family, which includes many other decorative plants. The most interesting feature of the shrub is the ability to adapt to different types of climates and different types of soils, making it a favourite of gardeners.
Appearance and Growth Habit
Carissa boxwood plants are evergreen shrubs to 3 or 4 ft tall x approximately 6 ft wide. The dark green, glossy oval to circular leaves up to an inch long are close to the size and appearance of true boxwood foliage, hence the common name. Not only are they attractive leaves, but they provide a nice contrasting background for the plant’s flowers and fruit.
As if its glossy foliage was not enough, the Carissa boxwood produces its flowers continuously – if you live in a warm climate – with its long-lasting fragrant, five-petalled white blossoms followed by their small, ovate, red or purple fruit. The fruit is edible, mildly sweet – although it is for decorative purposes often left on the plant.
Hardiness and Climate Preferences
One hardiness trait worth noting is that the Carissa boxwood plant grows best in USDA hardiness zones 9 through 11, making it a great choice for gardeners with warmer climates. The bush grows best in full sun to partly shaded areas and is adaptable to a large variety of soil types from sandy and rocky soils. It thrives in well-drained soil with slightly acidic to neutral pH.
The Carissa boxwood is also highly drought tolerant once established and can go long periods without water, making it a good, low-maintenance plant for arid or water-restricted areas. Rich in mineral nutrients, it also tolerates salty aerosol from salt-water spray, making the Carissa boxwood a great plant for coastal gardens.
How to Plant and Grow Carissa Boxwood
Planting a Carissa boxwood shrub properly is key to being able to help these plants thrive as you see fit. Whether this is your first time planting a Carissa boxwood in your garden or you are extending your existing landscape, getting it planted the right way is essential.
Site Selection and Preparation
Before planting your Carissa boxwood, make sure it will get plenty of full sunlight: while it will tolerate some light shade, it will produce more flowers and receive a denser covering of leaves when planted in a place that gets at least six hours of full sun per day, and in a site with a well-drained soil – waterlogged locations, allowing roots to sit in water, are prone to root rot.
And then dig the hole, tossing the topsoil aside in a pile. It should be twice the diameter of the root ball (or pot, if you’re planting a nursery bare-root) and slightly deeper than the height of the root is heavy (such as clay soil), mix it with some compost or other organic matter to loosen it.
Planting Process
Once your site is prepared, follow these steps to plant your Carissa boxwood:
- Take the plant out of the pot: Grab the edge of the pot and slowly squeeze the middle of it to loosen up the root ball. Gently tease the roots if they are intertwined.
- Flip the plant into the hole: Turn the plant to face the right way if it is upside down. Make sure the top of the root ball or root spread is level with where you dug the hole – do not plant too deeply or you will suffocate your plant.
- Backfill the hole: Scoop out the hole and reuse the excavated soil to fill it back in, compacting it lightly as you go to get rid of air pockets. Tread carefully, and don’t overdo the tamping – it’s important not to compact the soil too firmly because roots don’t like it when they have to force their way out.
- Now give a good deep watering, to firm up the soil and help the roots. Keep the Carissa boxwood well watered for the first few weeks, until it is well established.
- Mulch around the base: Create a circle of mulch around the plant’s base, 2 or 3 inches deep, to retain moisture and suppress weeds. Just make sure you leave a bit of space around the trunk so you don’t have any rot.
Ongoing Care and Maintenance
Once established, carissa boxwood plants are pretty low-maintenance, but they benefit from regular care to look their best.
Watering
The Carissa boxwood is notably drought-tolerant, although after planting regular watering for the first year is important to help the plant establish good roots. After the first season, reduce watering to once every two weeks during dry periods. Don’t overwater the plant: it does not tolerate soggy roots.
Fertilizing
Feed a balanced, slow-release fertiliser in early spring to maintain vigorous growth and flowering. A 10-10-10 or 14-14-14 fertiliser is preferable. Don’t fertilise heavily, as this will often result in green growth at the expense of flowers.
Pruning
While the Carissa boxwood doesn’t need to be pruned, it can be – once properly shaped – to keep its growth compact. The plant could be pruned back to maintain the shape, but once every couple of years should be more than sufficient. The Carissa box is pruned in late winter or early spring (the main planting season in California). You can prune back stems that have outgrown the shape you desire, as well as dead, damaged or crossing branches to encourage better airflow. You can also give some light trim back throughout the year, which encourages a fuller, denser shape.
Pests and Diseases
The Carissa is pretty resistant to pests, but do keep an eye out for the occasional infestation of scale insects or spider mites, which are easy to eliminate using a spray of insecticidal soap or horticultural oil. Keeping the plant well-watered and fed can also prevent a pest free-for-all.
Disease is also a possibility, but root rot is the most common (usually caused by poor drainage or overwatering), so be sure that your soil drains well and allow the top inch of soil to dry out before watering again.
Landscaping Uses for Carissa Boxwood
With its dense foliage, attractive flowers and decorative fruit, to beautiful red or orange or bronze leaves, the Carissa boxwood can serve you truly well and bring year-round interest to most any landscape, from the garden or meadow to the courtyard or veranda.
Hedges and Borders
Another very popular use of the Carissa boxwood is as a topiary or hedge plant. Its dense growth habit and tiny, glossy leaves make this shrub ideal for tight, formal hedges. Planting the Carissa boxwood in a line at the edge of your yard to create a defined boundary line or along a walkway or garden bed makes it the perfect shrub for creating a crisp, bold outline in your landscape.
Foundation Plantings
Carissa boxwood can also be used as a foundation planting on either side of a house or building, connecting the ground and the structure – although it will work best at a moderate size, to avoid dominating a space. In mixed planters, Carissa boxwood can add a bit of pop, while putting the focus on the rest of the garden. When planted in large groups, the Carissa boxwood can help create depth and a halo of greenery for plants or features in the foreground.
Container Gardening
Carissa boxwood is a great choice if you want to add greenery on a patio, balcony, or small garden. Given its small stature, never reaching more than a few feet in height and width, and its ability to tolerate a wide range of growing conditions, Carissa boxwood seems like tailor-made for container gardening. A fast-draining potting mix partnered with a container with drainage holes is key and could help make container-grown Carissa thrive in even the most urban environments.
Coastal Gardens
Salt spray may kill other plants, but the Carissa boxwood tolerates it, when combined with a little sand thrown around their roots The wind likewise causes problems for other plants. The boxwood’s healthy, dense-looking foliage is well-suited to coastal gardens, which require something to form windbreaks, or even to stabilise dunes or dress up beach houses. The Carissa boxwood also tolerates aridity: it’s one of the drought-resistant plants used to make coastal California landscaping more sustainable by other means.