Lithodora is a charming evergreen perennial known for its vibrant blue flowers and lush green foliage. It’s commonly found in rock gardens and along woodland margins, where its spreading habit and low-growing nature make it an attractive groundcover.
Lithodora flowers grow to a height of about 6 to 10 inches, with a spread of 18 to 24 inches, creating a striking visual display.
There are many types of lithodora — such as Grace Ward, White Star, Blue Star, and Heavenly Blue.
In this article, I’ll tell you how you can successfully cultivate and maintain lithodora flowers throughout the seasons in your garden.
Quick Lithodora Details
- Scientific Name: Lithodora diffusa, formerly Lithospermum diffusum
- Native Countries: Southern and Western Europe
Lithodora is typically found in Mediterranean-type climates, where it thrives in well-drained, sandy soils.
The name lithodora comes from the Greek word lythos (meaning stone) and dorea (meaning gift).
They are deer-resistant and generally hardy in zones 6 to 8. However, they can also survive in zones 9 to 10 — although you’ll need to be careful since stems and leaves can be damaged from the cold.
It grows best in full sun to partial shade, so I highly recommend it for rock gardens, pathways, and woodland margins. That’s because lithodora prefers environments with consistent moisture without becoming waterlogged.
As such, it’s important to water it regularly, especially during dry periods. However, you should also avoid overwatering it.
The plant has a low-growing, spreading shape with dense, dark green leaves that form a beautiful carpet-like cover.
This shape contributes to its effectiveness as a groundcover, suppressing weeds and providing a lush backdrop for the vibrant blue, star-shaped flowers I love so much.
I have found that lithodora needs to get the right amount of sunlight and be in well-drained soil to let its vibrant blue flowers bloom.
Pruning in the early spring helps to maintain the plant’s shape and encourages new growth, keeping it healthy and vibrant.
How to Help Your Lithodora Thrive
Lithodora thrives best during cool summers, where it can enjoy the sun with some afternoon shade to protect it from the intense heat of hot summer climates.
It prefers well-drained, acidic soil. However, I found that it can survive in heavy clay soil as well, as long as organic matter is added to it.
You typically won’t have to worry about pests like aphids or spider mites. If they do appear, you can spray the plant with insecticidal soap.
The plant is versatile and can be grown in rock gardens, along retaining walls, and even in containers or window boxes.
Proper Soil and Potting Mix
Lithodoras are acid-loving plants that prefer moderately rich and well-drained soil. This type of soil provides the necessary nutrients and drainage to support their growth and prevents water from pooling around the roots, which can lead to root rot.
For the best results, I recommend using a large pot with drainage holes to give the roots plenty of room to grow. Unglazed clay pots work great because they let extra moisture evaporate instead of keeping it in — which may be unhealthy for the plant.
Fill the pot with the required potting mix. Then, slowly water the soil until it is evenly moist. Like other container plants, your lithodora needs to be watered regularly to keep its soil moist and ensure that the roots can get the nutrients the plant needs to grow.
To keep the lithodora healthy, you can transfer it to a larger pot once the roots start growing out of the drainage holes or if it becomes root-bound.
I also like to divide and replant a section into fresh soil so it doesn’t get too crowded in a single pot.
Mulching and Fertilizer
I learned that lithodoras don’t always need fertilizer to bloom unless their leaves turn pale green-yellow. These colors indicate a nutrient deficiency or an alkaline soil pH, which needs to be addressed to prevent the flowers from dying out.
You can apply mulch and fertilizer formulated for acid-loving plants like rhododendron and azalea.
I advise against using granular fertilizers near the plant crown and foliage since they tend to burn the plant. Instead, use a diluted slow-release fertilizer to nourish the plant.
Lithodora Watering Schedule
You can water newly planted lithodora at least once a week to help its new roots grow into the soil and ensure that it doesn’t dry out quickly.
You can check if the soil is properly watered by sticking your finger into it. Ensure that about one inch below the surface remains damp.
Don’t let the soil become bone dry or soggy either. I’ve learned that overwatering could cause root rot, while insufficient watering can prevent proper root growth.
Preferred Climate and Temperatures
The lithodora is a low-maintenance plant, mostly at home in Mediterranean-type climates.
They can tolerate full sun in cool summer climates and more shade in scorching areas but may suffer in hot, humid conditions.
Sun Exposure
While lithodora thrives in full sun, it can also grow in part shade.
In hot climates, I recommend giving the plant afternoon shade to protect it from direct sunlight and extreme winds until it becomes established. This ensures that the dark green foliage and blue flowers remain healthy and vibrant.
Best Places to Plant Lithodora
It’s best to grow lithodora in sunny to partly sunny locations with humusy, moist, fertile, well-draining soils with an acidic pH — similar to the environment in the Deep South.
They can also be planted in a rock garden or small slopes as groundcover, adding bright royal blue flowers from late spring to late summer.
Other Guides from Planet Natural:
How to Plant, Grow and Care for Crocosmia Aurea Flowers – Full Guide
How to Plant, Grow and Care for Dianthus Flowers – Full Guide
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