Usually used as a groundcover in landscaping, the native Chinese and Himalayan Cotoneaster, or Cotoneaster apiculatis, is a wonderful bonsai specimen. It is extremely tolerant of human error, which makes it a pleasure to work with for bonsai enthusiasts of all levels.
This arching deciduous shrub is easy to grow and hardy with lovely small dark green leaves emerging from a grey trunk and branches. The Rock Cotoneaster is a beautiful spring interest plant blossoming with delicate white flowers in the spring that turn into vibrant red berries as mature fruit. In the fall you can expect red to purplish color before the leaves drop if keeping outdoors.
The Cotoneaster can be evergreen or deciduous depending on the climate it is grown in. This ensures that it can adapt to indoor or outdoor growing habits as long as provided with ample winter protection. In zones with extreme cold, it is best to bring this bonsai indoors over the winter, foregoing its dormant period.
This bonsai will thrive in a Sunny location with some shade provided in the intensity of afternoon sun.
Your Rock cotoneaster will need to be watered often in the summer months and less in winter, taking care to never allow it to dry out completely. Providing this bonsai with a humidity tray filled with stones will ensure proper root humidity without risking the root rot that is common when allowed to sit in water.
Fertilize with a water soluble food every two weeks during the growing season, and cease when flowering or fruiting.
Pruning / Training:
Cut back old growth in early spring before the appearance of new growth. You can encourage trunk thickening by cutting back suckers at the base. This plant will tolerate severe pruning. If desired, you can wire stems carefully in early spring before the buds appear. A Cotoneaster bonsai can be trained in most styles, although the cascade, curved trunk, and root over rock are desirable. Heavy pruning is tolerated well; scissor tip pruning is best.
Insects / Pests:
This bonsai is susceptible to aphids and scale, especially when kept indoors. To deal with aphids, a simple mixture of 1 tsp dish soap to 1 quart warm water sprayed over the entire plant until desired runoff is achieved is very effective at removing this pest. Be sure to rinse the solution well with tepid water and repeat as needed. Scale can be removed manually with a sharp knife or dabbed with a swab or ball of cotton dipped in isopropyl (rubbing) alcohol. Do not use other alcohols, such as ethanol or methanol, because they penetrate the plant tissues rapidly and will cause considerable damage to soft tissues!
After treatment, be sure to remove all scales by hand, large and small; allow the plant to dry and re-examine it for residual scale bodies. Repeat the alcohol wipe to remove all traces of the insects paying particular attention to the midrib, other veins, and leaf edge areas. Keep in mind that scale eggs are hidden under the waxy covering of the dead female, so if these are not thoroughly removed, the remaining eggs will hatch and continue the infestation cycle. Be sure to repeat treatment every 1-2 weeks until scale has been completely eradicated. Please be aware that a potentially rare problem that can occur with alcohol treatment is chilling of the plant tissues that can occur with the rapid evaporation of alcohol. This chilling is can cause over-cooling of the plant tissues, creating zones of dead cells that may become necrotic from bacteria or fungi. On warm or breezy days consider wiping any residual alcohol with a tissue instead of permitting it to evaporate off the plant.
This delightful little bonsai is best grown from soft cuttings placed in moist, well drained soil. Keep the cuttings in shade until adequate root growth has been established.
Repot your Cotoneaster every year or two in the spring. Be sure to prune up to 1/3 of the root growth before repotting in well drained bonsai soil.
Keeping the leaves free from dust with a weekly full body rinse will ensure proper cell growth, and is your best insurance against insects and disease.
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