by Ken Lain, the mountain gardener
This Arizona plum is the ideal small purple tree between evergreens. Blooms in a profusion of pink flowers that precede the deep purple foliage. Large enough to use as a front yard tree and behaved enough to use as a street tree. Plant pairs flanking gateways, driveways, or in an orchard-like row to screen a view of neighbors.
The purple leaf plum tree, Prunus cerasifera, is popular in landscape design for it’s deer and javelina-proof ornament quality. It goes by many names, Purple Twist Plum, KV plum, Thundercloud, and Newport plum, to name a few. All are small decorative trees with a vase-shaped habit. It produces fragrant, five-petaled pale pink to white flowers in spring roughly 1″ inch across that sometimes forms a small edible fruit. The leaves range in color from pure purple, with some displaying a green ting. This tree has a moderate growth rate and gains about 1-2′ feet per year. It’s best planted in the early spring and autumn.
Botanical Name Prunus cerasifera
Common Names Purple leaf plum, cherry plum
Plant Type Flowering Deciduous Tree
Mature Size 20′ feet tall x 15′ feet wide
Sun Exposure 6+ hours of mountain sun
Soil Type Well-drained
Soil pH 6-8
Bloom Time Spring
Flower Color Light pink, white
Hardiness Zones 5–8
Native Area Europe, Asia
Purple Leaf Plum Care
Purple leaf plum is a relatively short-lived tree, lasting around 20 years, and it requires a bit of maintenance. Yet growers still love it for its beautiful spring flowers and rich leaf color.
In terms of its care, plan to water your tree throughout the growing season, April through October, without sufficient rainfall. This tree also benefits from regular feeding and pruning. It can be a messy tree if fruit forms in spring. It’s best to plant this tree away from walkways and other sites in your yard that get a lot of foot traffic, so you are not walking on the fruit.
All Plum prefers soil that is rich in organic matter. The soil can be neutral to slightly alkaline. Good drainage is essential; Plums do poorly in soggy, wet soil.
1. Dig hole 2-3 times the width of the container but the same depth.
2. Score the root ball sides and bottom with a utility knife or pruners and place them in the planting hole.
3. Blend Watters Premium Mulch into the native soil at 1 part mulch with two parts soil dug from the hole and pack firmly around the roots.
4. Sprinkle 7-4-4 All Purpose Plant Food around the planting area.
5. Prevent ‘Transplant Shock’ by adding Watters “Root & Grow” to your water at 2-week cycles for the first 2 months.
6. Use the remaining Watters Mulch inside the tree well as a top dressing. This will keep weeds down, insulate roots from heat and cold, and keep the roots moist.
Purple leaf plum tolerates mountain wind, even on the highest ridgelines. She does best in at least 6 hours of sun; the more, the better. It can tolerate partial shade, but it comes at the cost of reduced bloom.
Water newly planted trees regularly with a garden hose for at least one month (2 months in Summer). Automatic irrigation systems may not be sufficient initially. Water frequency will vary according to season, exposure, and plant size.
April – Oct Plum should be irrigated 2 x weekly
Nov – Mar Plum should be irrigated 2 x monthly
Feed 4x Times per Year with either 7-4-4 All Purpose Plant Food, Soil Sulfur, or Humic. Here is the recommendation by season:
Spring = 7-4-4 All Purpose Food + Soil Sulfur
Summer = 7-4-4 All Purpose Food + Humic
September = 7-4-4 All Purpose Food
December = 7-4-4 All Purpose Food
Temperature and Humidity
The purple leaf plum is fairly tolerant both to cold and to heat. It’s hardy down to 0 degrees Fahrenheit. It can handle the high summer temperatures within its growing zones as long as it’s adequately watered. Humidity also is typically not an issue for the tree.
This tree doesn’t need an excessive amount of pruning each year. Simply prune to maintain your desired shape for the tree, and remove any dead, damaged, or diseased branches.
Purple Leaf Plum Varieties
There are several varieties of Prunus cerasifera, Purple Leaf Plum:
- Newport – The leaves on this tree are a bronze-purple in the spring, deep purple in the summer, and reddish-purple in the fall.
- Nigra – This tree has bronze leaves in the spring, very dark purple leaves in the summer, and orange-red leaves in the fall.
- Krauter Vesuvius – This variety looks similar to ‘Thundercloud’ but has even darker spring foliage and grows slightly smaller.
- Purple Pony – This is a dwarf variety that only reaches around 10 to 12 feet in height and spread.
- Thundercloud – This variety features deep reddish-purple leaves.
Is the Purple Leaf Plum Toxic?
The stems, leaves, and seeds of this tree are toxic when ingested both by animals and people due to their cyanide. Wilted parts of the plant contain a higher level of the toxin. However, the mature fruits are not toxic at all. This is also why animals like deer, rabbits, javelina, even elk leave this plant alone.
Symptoms of toxicity both for animals and people include difficulty breathing, an increased heart rate, dilated pupils, drooling, and muscle tremors. This is not common as the plant has a very bitter taste. Some animals have been known to eat the foliage, especially livestock in pastures where grazing is sparse.
This tree is prone to several pests and diseases. Insects that might infest the tree include Japanese beetles, mealybugs, borers, tent caterpillars, and scales. Common diseases include leaf spot, gray mold, verticillium wilt, and cankers. Pests and disease symptoms include discolored, wilted, or otherwise damaged foliage, along with poor growth and flowering. Ensuring proper growing conditions and good airflow among the branches can help to prevent many problems.