It may not have the most attractive name, but leadwort (Ceratostigma plumbaginoides) is definitely an attractive perennial flower. Also known as plumbago, this plant is a low-growing, mat-forming ground cover. Its erect stems bear oval, glossy, medium green leaves that stretch around 1 to 3 inches long. The foliage turns a blazing reddish-bronze in the fall, and new leaves emerge in a burgundy hue. Clusters of five-petal, star-shaped, bright blue flowers that stretch less than an inch across emerge in the mid-summer raised above the foliage. The blooms can persist into autumn up until the first frost.
Leadwort is known for its hardiness, and it can tolerate a variety of growing conditions. But it makes for such a fantastic garden plant thanks to the fact that it's fast-growing but not overly invasive. It is best planted in the spring after the threat of frost has passed. Don't delay planting, as leadwort needs a full growing season to get its roots properly established in the garden, or it might not survive the winter months.
|Botanical Name||Ceratostigma plumbaginoides|
|Common Names||Leadwort, hardy blue-flowered leadwort, plumbago, dwarf plumbago, hardy plumbago, blue ceratostigma|
|Plant Type||Herbaceous, perennial|
|Mature Size||9–12 in. tall, 12–18 in. wide|
|Sun Exposure||Full, partial|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Summer, fall|
|Hardiness Zones||5–9 (USDA)|
Leadwort plants are often used as a low-maintenance ground cover under shrubs or small trees, as long as enough light will hit their planting site. Because they are slow to emerge in the springtime, many gardeners will interplant them with bulbs that bloom in the spring, such as crocuses, sunflowers, hyacinths, and daffodils. That way, the leadwort foliage will emerge and mask the depreciating bulb foliage.
However, avoid combining leadwort plants with other perennials, primarily because they can outcompete other plants under optimal conditions. But this also means they are great at helping to choke out weeds. When given the proper growing conditions, leadwort doesn't require much care. Simply water if the soil is getting too dry, and fertilize in the spring and summer.
Leadwort plants can grow either in full sun or partial shade. The best flowering will occur in full sun, though the plants do benefit from afternoon shade in hot climates, particularly during the summertime.
These plants are tolerant to most soil types, including sandy, loamy, and clay soils, as long as their planting site has sharp drainage. They like a slightly acidic soil pH but can handle neutral and slightly alkaline soils as well.
Leadwort has moderate moisture needs. Water during prolonged periods of drought to prevent the soil from fully drying out. But make sure your plants don’t become waterlogged, as they can easily rot in such conditions.
Temperature and Humidity
These plants prefer fairly mild conditions. They will wilt in very hot weather but will typically bounce back once the temperature cools. They also benefit from a light layer of mulch for winter protection, especially in the colder parts of their growing zones where they might not be fully hardy. Be sure to remove the mulch come spring once new growth is beginning. Humidity typically is not an issue as long as their soil moisture needs are being met.
Leadwort likes a somewhat fertile soil. Apply a balanced, slow-release fertilizer in the early spring as new growth is picking up. Fertilize again in the early summer to help the plant fill out. Do not fertilize in the late summer, as this will promote tender new growth that will be vulnerable and could weaken the plant as the fall temperatures cool.
Besides Ceratostigma plumbaginoides, there are several other types of leadwort, including:
- Plumbago auriculata: Also known as cape leadwort, this plant features deep or pale blue, cup-shaped flowers.
- Plumbago europaea: Known as common leadwort, this plant sports dusty pink to lilac flowers.
- Plumbago indica: Also called Indian leadwort or scarlet leadwort, this plant has bright red or deep pink flowers.
Because these plants are slow to leaf out in the spring, many gardeners opt to leave the old stems in place to mark where a plant is. That way, they don’t accidentally disturb it by trying to plant something else in the area. Cut back the old stems in the spring as soon as new growth starts to appear.
While leadwort plants can self-seed and spread via rhizomes (underground stems) in the garden, they also can be propagated through stem cuttings. Trim roughly a 3- to 6-inch piece of stem during the early summer, and remove the leaves on the lower half. Apply a rooting hormone to the cut end, and plant the cutting in a soilless potting medium. Keep the medium evenly moist but not soggy. Once you feel resistance when you lightly tug the stem, you’ll know roots have developed. Then, you can plant your cutting in the garden.