Semi-cascade Chinese elm: the angle that decides the style

Semi-cascade sits in the narrow band between a slanting tree and a full cascade, and the difference comes down to about 15 degrees of trunk angle. On this elm the whole design was settled by one decision made in 2021 about how far the trunk should tip.

From nursery whip to angled trunk in two seasons

This tree was bought in 2021 as a 3 cm nursery elm with a straight 45 cm trunk and almost no lower branching. In May 2021 the trunk was wired with 2.5 mm aluminium and bent to 55 degrees from vertical over three weeks, in four passes. The 55 degree figure was chosen specifically because it puts the lowest foliage at roughly the height of the pot base — 5 degrees less and it reads as a slanting tree, 10 degrees more and the foliage drops below the pot and the planting becomes a full cascade.

Building a cascade branch from a straight shoot

The descending branch is the design, and it began as a single upright shoot in June 2021. It was wired downward in stages of about 20 degrees every three weeks until it ran below the pot rim, then left to lignify for a full season. In 2023 it was thinned to a framework of three secondary branches, and by 2025 the ramification reached four levels. Total descent from the trunk fork to the lowest foliage tip is 34 cm.

Growth control on a fast species

Chinese elm will produce 60 cm of extension in a season if allowed to, which on a cascade destroys the line in a single summer. Shoots on the descending branch are cut back to two leaves every three weeks from May to September — about seven sessions a year. Shoots on the top of the descending branch are removed entirely as soon as they appear, because they grow upward against the direction of the design. The result is a tree that needs almost no fertiliser: half strength every three weeks from April to August, and nothing over winter.

Watering a cylinder in winter

The 13 cm cylinder holds little more soil than the tree's root mass, and in summer it needs water twice a day. In winter the opposite problem appears: the semi-evergreen canopy keeps transpiring while the roots are nearly dormant, and a cylinder that stays wet in a cold frame will rot the lower roots. From December to February the tree is watered about every fifth day, only when the top 2 cm of soil is dry, and it is kept at 2 to 6 C in a light but frost-free position.