Microbiota Decussata: Shrubby, Low-Growing Ground Cover
Microbiota decussata, the Siberian cypress, makes a fantastic low-growing shrub or ground cover plant. Our guide tells you how to grow it!
Looking for an alternative ground cover that’s reminiscent of juniper? Siberian cypress, botanically known as Microbiota decussata, is great. This evergreen, low-growing shrub has a wealth of garden uses.
Unlike junipers, it’s a bit more shade-tolerant. Its bright green leaves turn a coppery bronze in the fall, adding to its appeal. Spreading with ease, it will gradually fill in an area with lush color.
Though it was found in 1923, the world didn’t discover the plant until nearly fifty years later. Since then, it’s become beloved for its feathery foliage and good looks. You’ll love it, too!
So let’s settle in and discuss this short little shrub and how best to incorporate it into your garden.
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Quick Care Guide
|Common Name(s)||Siberian cypress, Russian cypress, Russian arborvitae, Celtic pride|
|Scientific Name||Microbiota decussata|
|Family||Cupressaceae, the cypress family|
|Height & Spread||8″-12″ tall, with a spread ranging from 6′-12′|
|Light||Full sun, partial shade, or light shade preferred.|
|Soil||Moist but well drained soils, tolerates poor soils, but not poorly drained soils|
|Water||1x weekly, more frequently in hot weather|
|Pests & Diseases||Root rot may be an issue in improper conditions. No common pests.|
All About Microbiota Decussata
In the spring, the Celtic pride plant’s foliage is bright, vivid green. As the seasons shift, this member of the cypress family becomes dark green in summer, then gradually turns to a bronze hue for the fall. It remains this color until the spring returns, and then undergoes a dramatic shift back to green.
Mountainous portions of southeastern Siberia are where its native range lies. Because of political secrecy, the USSR did not share it with the rest of the world… at least for a while. Nearly fifty years after it was first named, it was revealed to the world at large as a medium maintenance planting.
Its foliage has a feathery shape. Each of the fan like sprays is comprised of many overlapping scale-like bits, giving it texture. These join together at the stem to create a fan or feather-like spray. Where juniper tips tend to curve up towards the sun, these branch tips gracefully bend downward.
While it does flower (especially in its native range), its flowers are ornamentally insignificant. From the spent flowers it forms its fruit. These are tiny spherical cones, each one covered in woody scales. They look like a brown berry from a distance, but the layering of woody scales on these berry like cones is visible up close.
It’s considered an evergreen conifer, as it does not shed bright green leaves in the fall. As it grows, newer growth appears over the older stems, overlapping old growth. Usually, it stays at a height of 8″-12″, but can spread anywhere from 6′-12′ in diameter. This makes is great for rock gardens.
Often, this plant is used in foundation plantings on hillsides for erosion control. It makes an excellent lawn replacement in mass plantings. When combined with other evergreen plants, it can be quite striking. This is especially true in its fall coloration, as its dark bronze stands out from greener plants.
This lovely shade tolerant plant is easy to grow, and won the Royal Horticultural Society Award of Garden Merit, too!
Siberian Cypress Plant Care
Conifers like Celtic pride tend to be pretty self-reliant, needing medium maintenance from humans. The Russian arborvitae is no different in this regard! Let’s talk about setting up your Siberian cypress for success. With the right start, it will provide living color for you for years to come.
Light and Temperature
While creeping juniper prefers full sun conditions in its native range, your Siberian cypress enjoys partial shade, and is fairly shade tolerant. In fact, that’s where it grows best. While it can tolerate full sun conditions in cool summer climates, it’s easiest to plan for some cover. It can grow in full shade, but performs best if it gets at least a little sunlight.
Zones 3-7 are where it grows best, and this is where it will thrive in full sun. It’s been known to survive in limited plantings in zones 8 and 9, but must be fully-shaded. It’s very cold-hardy, making it perfect in areas with chilly winters.
However, the opposite is not true of Microbiota decussata. Hot summers are a no-go, and the plant will die if exposed to heat or full sun in these areas for too long.
Water and Humidity
Your plant with its fan like sprays will enjoy consistent moisture, but it doesn’t like standing water. Keep the soil evenly damp, but not soggy to avoid problems, like root rot. Once established, the Russian arborvitae is very drought-tolerant. Its roots can pull moisture from deep down.
I prefer a slow, gradual irrigation method for the Celtic pride plant. Knowing how to use a soaker hose, and placing one beneath your plants when they’re young is best. This allows the moisture to ooze into the soil and thoroughly permeate. Water only when the soil is dry at the surface, but do a long, slow watering to soak the soil to 6″ down.
If your climate has humid summers, be sure that your plant has some shade during the hottest parts of the day. The combination of humidity and heat in humid summers can slow down its growth. Night humidity isn’t a concern.
Moist and well-drained soils provide the best growth for your Russian cypress. These plants can tolerate poor soils, as well as dry and thin ones, but they will grow quickly in loams. Rock gardens are perfect spots for your M. decussata.
When possible, provide a rapidly-decomposing mulch like mulched dry leaves around new plantings. This helps to keep the soil moist and protects it from erosion. Once the plant has established itself and expanded in size, it will act as a living mulch.
In winter, a wood chip mulch will protect the Celtic pride plant’s roots from cold damage. Poorly drained soils will cause problems for Russian cypress, so avoid planting in poorly drained soils.
Fertilizing Microbiota Decussata
If you plan on fertilizing Celtic pride, it’s best done in the early spring before new bright green growth appears. Use a balanced, slow-release fertilizer, preferably a granular form. These are easy to spread around the base of your plants.
Don’t feel as if it’s a necessity, though. Your Russian arborvitae is quite tolerant of poor soil nutrition. It’ll survive even without fertilization. If your soil’s fairly rich, you can skip it with no problem.
Microbiota Decussata Propagation
Propagation for the Celtic pride plant is mostly done via stem cuttings. To take a cutting, select a healthy stem and cut it with sterilized pruning shears. Rooting hormone can help speed root development. Keep the cutting in moistened potting soil until it develops roots. Humidity around the young cutting can help keep it vigorous.
Seeds also form in the plant’s berry like cones, but these are slightly less reliable. When the tiny berry like cones begin to open, you can shake the seeds free into a paper bag. Plant seeds shallowly and keep the soil moist until a young plant has developed. A greenhouse cover and a seedling heat mat and thermostat are useful for germination.
Pruning Microbiota Decussata
Prune in the early spring, focusing on the tips of branches. Be sure to prune before the plant begins to green up again. This annual pruning encourages bushier growth habits.
You may also prune your Celtic pride to ensure it remains in its intended growing area at any time. When pruning, be sure to use clean pruning shears to make a clean cut. Don’t use a weed whacker or edger, as this can cause potential damage to the rest of the stem.
You might be surprised at just how care-free growing Microbiota decussata will be. It handles most of its own needs, with only minimal care from you.
But what of problems you might encounter? Let’s talk about those.
Overwatering is likely the riskiest situation for your plant. It just can’t tolerate standing water, which is why it thrives in rock gardens. The plant’s roots will suffer if you overwater, and it can cause major problems. The same goes if you don’t plant it in well drained soils.
Hot climates, and those with humid summers can be very, very tricky for Microbiota decussata. While it is possible to grow it in hardiness zone 8 or 9, it really needs to be in full shade rather than full sun. The heat of direct sunlight in those warmer regions can be deadly to the plant. Generally, it prefers cool summer climates.
Don’t panic when your plant starts to turn bronze in the winter! It’s a normal progression. It will green right back up in the spring again. Mulch around the plant’s base with wood chips to keep the roots insulated from cold.
Unlike many other groundcover junipers, Siberian cypress is essentially pest-free. At most, deer may nibble on exposed foliage for food during a snowy winter. It’s not their preferred food, and they’ll choose alternatives whenever possible.
While pests don’t attack the plant, it can house pests. Mice may be discovered living in burrows under this and other ground cover plants. Some spiders find it to be a good home, too.
Like pests, diseases don’t typically strike your microbiota plant. It’s immune to many types of plant disease.
Damaged roots may rarely be susceptible to bacterial or fungal root rots. Similarly, damage to the base of the plant may leave it open to bacterial infection. But it’s pretty unlikely as a whole.
Frequently Asked Questions
Q: Are there different varieties of Siberian cypress that can be grown?
A: To date, there aren’t cultivars in development, just the main species. This ground cover plant is fantastic on its own!
Q: I live in an area with cold winters and strong winds. Is it okay to grow Russian cypress here?
A: Russian cypress can survive colder weather as well as strong windy conditions. It overwinters well under a blanket of snow.
Q: Is microbiota decussata safe around my pets?
A: The ASPCA does not currently list this plant as a hazardous plant. If your animal eats a large quantity of the foliage, you may want to check with your vet. Your pet may be suffering from some gastric upset and may be trying to induce vomiting. Most dogs and cats will have little interest in it, though!
Q: How much light does microbiota Decussata need?
A: In a cool hardiness zone, full sun is needed. In a warm hardiness zone, full shade is best.
Q: What is the use of microbiota Decussata?
A: It’s great for rock gardens, hillsides, and groundcover plantings.
Q: What color is microbiota Decussata in winter?
A: The fronds turn a light purple bronze color in winter.
Q: Do deer eat Russian cypress?
A: Deer avoid this plant. That makes it good for border plantings where you’d like to keep deer away.
Q: What is the best feed for cypress trees?
A: You don’t need any fertilizer for this plant. If you’d like to, add a balanced, slow-release fertilizer, preferably a granular form. These are easy to spread around the base of your plants in early spring.