How to Plant, Grow and Care For Plumbago Flowers
In this article, gardening expert Kaleigh Brillon talks about how to care for plumbago, a beautiful flowering shrub that thrives in tropical climates. This plant also makes a pretty houseplant if you don’t have the warm temperatures it prefers.
Are you looking for a versatile flowering shrub for your garden? Plumbago is a showy plant with beautiful flowers native to South Africa. In zones 9-11, it grows as an evergreen shrub with gorgeous blooms all year. It can work as a climbing annual or a beautiful potted plant in cooler climates.
This easy-going shrub requires little attention besides plenty of water and pruning. The plant can easily go wild, but if you have room to do so, it’s sure to be a statement piece in your landscape.
Let’s explore how to plant, grow, and care for plumbago.
Plumbago Plant Overview
Plant Type Shrub
Species Plumbago auriculata
Native Area Tropical regions
Hardiness Zones 9-11
Sun Exposure Full sun to partial shade
Height 6-15 feet
Watering Requirements Medium
Soil Type Neutral, sandy, well-draining
Pests & Diseases Cotton cushion scales, mites, thrips
Plumbago is a genus of large shrubs that grow hundreds of small white, blue, or pink flowers. Plumbago auriculata, also known as cape leadwort, is the most popular variety in the US, with clusters of delicate periwinkle flowers.
The pastel flowers stand out against the dark green leaves, bring in many pollinators, and develop small decorative fruits you shouldn’t eat.
Plumbago becomes a stately plant up to 15 feet tall in ideal conditions. If you’re in a cold climate, grow it as a small ornamental shrub in a container to bring indoors through winter.
Though pretty to the eyes, plumbago isn’t nice to the skin. It’s moderately poisonous and can cause redness, irritation, and even blisters when you handle it. Always wear gloves to protect yourself, and keep your plumbago away from children and pets.
Growing plumbago is pretty easy, and there are a few different ways to do it. If you think you can’t grow it in your region, try a different method!
Growing this plant outdoors is the best option if you want it to become large and bloom a lot. If you want it to reach its full size, give it plenty of room to grow. You can also prune it to maintain a smaller size. It is particularly attractive as a hedge or foundation plant.
It also works well as a vining plant. You can also train it to grow vertically by providing a fence or trellis for the plant to climb.
Plumbago will grow well in an outdoor container. It likely won’t be able to reach its maximum size, but supporting it with a trellis in the container will allow it to grow pretty large. If you live below zone 9, bring it indoors when the weather gets too cold so you can keep the plant in a warm environment.
You can grow plumbago indoors as a houseplant or in a greenhouse container. The plant will stay pretty small, though repotting it into larger containers as it grows will help it develop quite nicely.
Plumbago is most likely to flower only in the summer when your indoor location is warmest. If you can keep the temperature similar to what it would expect in its natural habitat, you might get it to bloom all year. You’ll likely need a sunroom or greenhouse to make this happen.
This genus consists of several species, all of which are native to tropical regions and flower year-round.
The Plumbago Genus
Plumbago auriculata is the most popular in the US. It’s native to South Africa and typically has blue flowers.
P. pulchella is native to central Mexico and is nicknamed cola de iguana, or iguana’s tail. It usually has thorny stems and light purple flowers.
Plumbago europaea is native to the Middle East and Mediterranean. The flowers range from purple to pink and like beachy environments.
P. zeylanica has white flowers and an admittedly confusing background! Depending on which professionals you ask, it is native to either India or Florida. Regardless of its history, it grows well in the US in the right hardiness zones.
The Ceratostigma Genus
Some plants are colloquially called plumbago but belong to a different genus called Ceratostigma. Ceratostigma and plumbago plants are similar, though the former is much shorter, usually reaching up to four feet.
While they have similar growing requirements, this growing guide is for the Plumbago genus and may not be entirely accurate for Ceratostigma. Still, it’s worth mentioning since you may see this genus when hunting for plumbago plants.
Though they’re not actually plumbago shrubs, plants in the Ceratostigma genus make a great alternative in temperate zones since they’re significantly more cold-hardy. They can survive down to USDA zone 5, extending their growth potential into regions of Canada.
Chinese plumbago, or Ceratostigma willmottanium, is a popular option with bright blue flowers. It grows in most of the U.S.
Propagation and Planting
Plumbago is easy to transplant and propagate. Once you have one established plant, you’ll have an unlimited potential supply!
Getting plumbago seeds to grow successfully in your garden is super easy. Seeds are ready to harvest once the flowers dry up. You’ll see them hanging on the plant where the flower used to be. If you’re planting for the first time, you can find seeds online.
In late spring or early summer, use 4-inch seed-starting containers with a loose growing medium so the seedlings can easily root. Plant the seeds ¼ inch deep, with only one or two seeds in each container. Place the seeds in a sunny window or under a grow light.
Keep the soil moist but not soggy. The seedlings should sprout within four weeks. If multiple seeds sprout, thin them out so only one remains. Harden them off (expose them gradually to outdoor temperatures) before transplanting them outside.
You can also propagate plumbago via root cuttings. While slightly more difficult than taking stem cuttings, the success rate is usually higher.
Start with a 2 or 3-year-old plant to ensure it has mature roots. If the plant is too young, you risk injuring it and having unsuccessful cuttings.
Dig around the mother plant until you find a clump of roots that are ¼ to ½ inch in diameter, and remove them from the plant. Use sharp tools to remove the entire clump and not just the roots so you don’t damage the plant.
Cut the roots into 4 to 6-inch sections. Prepare a shallow tray or container of soil, lay the root sections on top, and then cover them with a half-inch of soil. Keep the soil moist and place the cutting in a sunny location; grow lights also work well.
New shoots should develop in two or three weeks. Wait four weeks before transferring the seedlings to their own containers. Once the plants have established themselves in their new containers, you can harden off the plants to prepare them for the outdoors.
Stem cuttings are much easier to obtain than root cuttings, but their success rate isn’t as high. Take several cuttings at a time in case some fail.
A major benefit of taking stem cuttings is you don’t need a mature plant to get started. Regardless of the plant’s age, choose new growth that’s still flexible. You can choose older growth, but ensure it’s not flowering, or it won’t take root.
Wait until late spring to take a cutting. Cut the stem to three or four inches long with two leaf nodes, cutting just above a pair of leaves to remove it from the plant.
Then, cut the stem below the bottom set of leaves and remove the leaves. You can leave the leaves on top—just make sure it’s only a node at the bottom.
Soak the node in water, and dip the cut end in a powdered rooting hormone after soaking for the best results. Choose a container at least as deep as the stem, and make a small hole with a pencil or stick. Bury the stem so that the leaves are sticking out from the soil.
Keep the soil moist and the plant in indirect sunlight. Direct sunlight will evaporate water too quickly and create too much heat for the plant. You can leave the cutting outside, but ensure it’s in full shade. A plastic bag over the top will help retain moisture, but remove the bag and wipe out condensation every so often to remove excess moisture.
Stem cuttings will take about one month to develop roots, and you should wait another two months to plant them outside. Plant them in the fall or overwinter them inside for spring planting.
Clump division will be stressful for the plant but easy for you. If you go this route, be extra careful when handling the plant. Wait for autumn when the temperatures cool down, and all the flowers finish flowering. Only divide clumps from a two or three-year-old plant so its mature roots will have a better chance of acclimating.
Water your plant deeply the night before you divide it so its roots are well-watered and easy to remove. When it’s time to divide, identify a root clump and how far the roots stretch. Clumps should have three to five stems. Try to pick new growth, as hardwood stems will likely not survive the transplant.
Use a sharp trowel or spade and try to keep three inches of soil around the clump to prevent damaging small roots. Place the plant in a hole the size of the root ball, backfill it with soil, and add an inch or two of mulch to protect it and keep it watered.
Don’t plant divided clumps closer than three feet from another plumbago plant, and keep the plant well-watered until it’s about a year old.
Layering, or marcotting, is preferred for laidback gardeners who want to work smarter and not harder. It has a high success rate, but you’ll have to have the new plant next to the old one or transfer it to a container before planting it elsewhere in your garden. This method involves taking a flexible branch, bending it to the ground, burying it, and waiting for it to take root and develop new growth.
Autumn is the best time for this method because the new plant won’t have to battle the hot sun while it establishes in your garden.
Start by clearing the ground and lightly tilling it, or prepare a container by filling it with soil. Pick a long new branch that can bend without snapping. It will work well if you can bend it into a U shape.
Make a small cut lengthwise on the branch, no more than an inch long. Leave enough room between the mother plant and the cut so the plant will have enough room to grow. Don’t make a deep cut; all you need to do is score it. Then, apply a rooting hormone to the cut you made.
Bury the cut stem about two inches deep in the soil, whether that’s in the ground or in a container. Stake up the part of the stem that isn’t attached to the mother plant so it will grow straight up. If you skip staking it, your plant may not grow where you wanted it.
Keep the plant moist but not wet for the following months. If the new plant has established roots in the spring, cut the stem attached to the mother plant. If you put your plant in a container, you can move it to wherever you’d like.
When planting it in the ground, ensure it’s well-established before doing so. Otherwise, you’ll risk stressing and potentially killing your young plant.
Hardening Off Young Plants
Hardening off is a crucial acclimation method for any young plant. You can use this method for plants you started from seed or by cuttings.
If you started your seeds in late spring or early summer, they should be big enough to harden off by mid-summer. Keep the plants outside in full shade. Exposure to sunlight from the start could damage and kill them by being too hot or drying them out too quickly.
Once fall approaches, you can give them some sunlight to see if they’re ready to plant outside. If so, they can be planted in early fall.
If you don’t want to risk your young plumbago getting damaged by cool winter weather, leave them inside until spring.
How to Grow
Plumbago is easy to care for in the right environment. But, if you’re growing below zone 9, you may find it to be a bit tricky. Let’s take a look at how to care for this tropical-loving plant.
Plumbago looks its best when it has access to full sunlight for at least six hours. It will prefer even more than that, so give it as much as possible. If grown indoors, keep them by a sunny window or give them a grow light.
When you’re hardening off new seedlings, they must be in full shade if they’re outdoors. Keep tender plants moist so the sun’s heat doesn’t dry them out or burn their leaves.
Keep your plumbago in moist soil, ensuring that water can never puddle and that there’s good drainage. One inch of water per week should suffice, but you may need to increase this during drought or excessive heat. This is especially important for young seedlings and plants you’re hardening off.
Established plants that have been in the garden for at least a year can tolerate slight drought conditions, but you should try to prevent that the best you can if you want the plant to thrive.
Indoor plants typically require less water. Container plants kept outside or in greenhouses often need to be watered more frequently since container soil dries out quickly.
Plumbago is pretty tolerant of most soils, though it thrives in sandy soil that drains well. Avoid heavy clay soils since they don’t drain well, or amend them with sand to create a loamy texture.
It prefers a neutral pH of 6.0-8.0 but tolerates mildly acidic or alkaline soils. However, a pH over 8.0 (alkaline soil) may cause a nutrient deficiency, resulting in yellow leaves.
These shrubs have a tolerance for salt since they come from tropical regions. They can tolerate salty, sandy soils if you live near the ocean.
Climate and Temperature
Plumbago is sure to be happy in USDA zones 9-11, though you may find some success in zone 8 if you can protect your plant from freezing temperatures. If winter dips below 20°F in your zone, you must keep your plant in a container and bring it inside during the cold months.
Plumbago is native to tropical regions that receive plenty of rain. If you can provide warm weather and moist soil, you can grow this plant with few problems. You can achieve this indoors with grow lights and heating mats or use a greenhouse.
Give your plant as much organic matter as possible. A fresh layer of compost mixed into the soil once or twice a month will help the plant stay healthy and continue flowering. If your plant doesn’t flower all year, you can limit compost refreshing to the growing season.
You can also give your plant a slow-release fertilizer in early spring. Choose a general all-purpose fertilizer or a product designed for shrubs. Granules only need to be applied once yearly unless specified otherwise on the packaging.
Plumbago will let you prune it any time of year with no problems, making it easy to care for. Every spring, trim back any branches damaged by frost. Throughout the year, prune excess and unruly growth as needed.
Pruning isn’t a requirement unless your shrub starts to take over. If desired, train it up fences and trellises to help keep it contained. Container plants will be much smaller than ones in the ground outside, so if you don’t have room for a giant shrub, consider growing it in a container.
Pests and Diseases
Plumbago doesn’t have any major disease problems, though there are a few pests that might bug them. Fortunately, you can prevent and treat them without hurting your shrub.
Cotton Cushion Scale
The cotton cushion scale (sometimes called cottony cushion scale) is named for its cotton-like appearance. The scales range from orange to brown, but the egg sac has a cotton appearance. If you see puffy white bumps all over your plumbago, you may have a big problem.
Scales eat the sap out of shrubs and trees. They can cause discoloration or deformation of stems and leaves, and large infestations could kill the plant.
Two predatory insects will help control your cotton problem: the Vedalia beetle and the parasitic fly. The vedalia beetle is a type of ladybug that lays its eggs on the scale. The ladybug larvae feast on the contents of the egg sac. The parasitic fly behaves similarly by laying eggs in scale larvae, which the fly larvae will eat their way out of. (Nature is pretty gross, isn’t it?)
If you have cotton cushion scale, you probably have an ant problem. Scales create honeydew, which ants love. Ants will turn your shrub into a scale farm and will keep them around so they can enjoy the sugary goodness. Keep ants away with cinnamon, wash them off with water, or revert to harsher means with chemical pesticides for ants.
Prevent the scale problem by ensuring your plant has plenty of airflow. They thrive in cool, moist conditions, so removing enough branches to let the sunlight in and letting your plants stay on the dry side helps clear them out.
For large pest problems, use pyrethrin sprays. However, avoid using pesticides if you see evidence of ladybugs or parasitic flies. Fighting these pests biologically should be enough because pesticides kill all bugs, whether good or bad.
Mites are another plant-sucking problem that will hurt your plumbago. The bad part of this pest is that you probably won’t see them until they’ve already damaged your plant. They’re so tiny that you’ll probably need a magnifying glass to see them.
You’ll notice spider mite damage when you see small brown dots on the leaves. The leaves will turn yellow or red and then drop off the plant. Lost leaves shouldn’t hurt the plant unless it’s young or loses many leaves at once.
Thorough watering is the best way to prevent mite damage since stress can make plants more susceptible.
Many insects eat spider mites, including predatory mites, predatory six-spotted thrips, lacewing larvae, and the spider mite destroyer lady beetle, a tiny solid black ladybug. If you see these insects in your garden, leave them be! They’re helping you out.
If predatory insects aren’t helping, wash mites off with water or spray them with neem oil or insecticidal soap as a natural means to eliminate them. They need the leaf sap to survive, so washing them off will help kill them. Neem oil and insecticidal soap will suffocate them and greatly harm their population.
Pesticides are also an option if natural means aren’t working. Look for options designed for mite control. Remember that these chemicals will harm other insects, including beneficial insects like predators and pollinators.
Thrips are small insects that can be yellow, black, or brown. They also suck sap from leaves that will result in spotted or curling leaves, eventually stunting plant growth. Thrips are easier to spot with mites, though you may not notice them until you have visible leaf damage.
Wash thrips off with water or use insecticidal soap or neem oil to get rid of them naturally, or you can let predatory mites eat them.
Chemical control usually comes in the form of an all-purpose pesticide for shrubs. This type of pesticide usually kills thrips, mites, and many other insects. It may harm beneficial bugs, though, so be careful when you apply them to your shrubs.
Plumbago is an easy plant to care for, and because of the many ways you can propagate them, they’re easy to plant all around your garden. They like warm, tropical weather but can also be content as houseplants. Keeping them in a container is ideal for cool climates so you can protect them from harsh winters.