Growing Tips
Location: A subtropical species, the Chinese elm adapts perfectly to our temperate climates. Accepting temperatures ranging from -5°C to +30°C, it should be grown outdoors in light. During the summer, however, the Chinese elm prefers a semi-shaded location especially when the sun becomes bright and scorching, the ideal would be to find it preferably in an eastern exposure, in order to give it the morning sun and protect it in the afternoon.
In winter, maple needs and will withstand the cold, especially keep it outside! As a precaution, you can protect the roots (the pot) when temperatures are below zero (especially during heavy frosts), for example by using a winter fleece, glass wool, etc.
Watering: Chinese elm needs a substrate that is always moist. Water it regularly while allowing the root ball to dry out slightly between waterings to avoid excess water. In spring/summer, watering will be done regularly, when it's hot, it's every day ! On the other hand, in winter, water according to the supervision of the soil. Thanks to the rain and cold, you won't necessarily need to water regularly since the substrate will remain moist.
Important: Don't hesitate to water the whole root ball up to the roots, the water will drain through the holes under the pot or bathe it in water (drenching) for a few minutes, to make sure you water it well. We do not recommend putting a cup/container under the pot as the water will stagnate and can cause root rot. (Too much water = asphyxiation).
Repotting and substrate: Repotting is done in spring (March), when the buds turn green, just before bud break. Cut off the longest roots around the edge of the root ball but don't reduce it by more than a third, many bonsai trees react noticeably when repotted at the wrong time or too drastically. The youngest ones are repotted about every 2/3 years and the older ones can stay in their pot for 4 to 6 years, with good maintenance.
The Chinese elm likes cool soils with a good share of organic matter to maintain their good moisture, inthe nursery, we use potting soil which is composed of black peat blond peat, eco aged, topsoil, horse manure, pozzolana..
> Everything you need to know about repotting a bonsai - Pépinière Bonsai Galinou
Pruning : The Chinese elm grows quickly and from March to September, it develops long stems. The shoots gradually change from green to brown, they become lignified and turn into wood. Prune the lignified part and cut back 2 or 4 pairs of leaves. You can also cut off misplaced shoots by following the shape of the tree's flat trays.
Fertilization: In the nursery, we use blue tomato/flower fertilizer NPK 12 12 17. You can use some and put a handful (small or large depending on the size of the pot) on the substrate from May to October, every 2 months alternating chemical/organic.
» Complete Guide to Caring for a Chinese Elm in Bonsai