Acer campestre/Field Maple

Bonsai Species Guides

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field maple spring leaves

Acer campestre Spring growth.

BONSAI CULTIVATION NOTES

POSITION
Full sun throughout the growing season. Field Maples have much stronger leaves than Acer palmatum. Weak-rooted specimens may suffer from leaf scorch in Summer and can be afforded some protection from the sun.

Very tolerant of frost but some frost protection is required when temperatures drop below -10°C or for trees in very small pots.

WATERING Though tolerant of quite dry soils, Field Maples prefer damp conditions in a well-drained soil for maximum health and vigour.

FEEDING
Feed every two weeks from bud-burst to leaf-fall. Trees in development can be heavily fed to increase growth rate and trunksize. Reduce or withhold feed until midsummer on developed bonsai to reduce the coarseness of new growth.

REPOTTING
Every one to two years as buds extend. Developed Field Maples are repotted much less frequently in an effort to reduce leaf-size and the coarseness of new growth.

field maple bonsai roots

The nebari, or surface roots, of a Field maple, by Harry Harrington.

Field Maples are very tolerant of heavy root pruning and easily form dense, fibrous root systems suitable for bonsai cultivation.

field maple bonsai

Superb Acer campestre / Field maple bonsai by Brian Wallin, seen at the Middlesex Bonsai Show 2015.

field maple bonsai

The greatly reduced leaf-size of Brian Wallins' Acer campestre / Field maple bonsai.

PRUNING Trim back new shoots to one or two pairs of leaves throughout the growing season unless branch extension is required. Remove all shoots with long internodes. Shoots normally regrow after only 2 or 3 weeks.

Prune large branches or trunk-chop either after leaf-fall to avoid excessive sap-bleeding in early Spring, or at midsummer to take advantage of very quick wound-healing times.

Twig denseness and ramification can be increased dramatically using defoliation techniques and by removing large leaves and coarse growth throughout the growing season.

For further pruning details please refer to the Advanced Acer palmatum article at Bonsai4me.com. The guidelines on Trumming, Defoliation,Branch Pruning, Pinching Back, Internode Distances, Use of Sapdrawers and Positioning as all as equally applicable to Acer campestre as they are to Acer palmatum.

REDUCING THE COARSENESS OF ACER CAMPESTRE GROWTH Field Maples have a reputation of being relatively easy to build thick trunks, thanks to their vigour. However, while trunk development can be relatively fast, branch development can be slow and frustrating, typically taking many years to accomplish due to the coarse vigorous growth of the species that does not lend itself to the fine ramification required of a high quality bonsai.

However, fine growth with short internodes is achieveable. Withdrawing fertilizer from bud-burst (early Spring) until midsummer, when the tree is defoliated, will greatly help reduce the coarseness of growth. After defoliation, Field maples can then be fed as required to encourage vigour.

Field Maples have a habit of producing many suckers and back-buds along their branches in Spring; while it is normal to remove such growth from most bonsai immediately, its retention on Field Maple through Spring will help to reduce the vigour, and coarseness, of new growth. Suckers and any other unwanted growth, used as "sapdrawers" can then be removed at midsummer during defoliation.

All new shoots in Spring (excepting sapdrawers) should be pinched-out leaving no more than 2 or 3 new leaf-pairs.

Healthy Field Maple can be completely defoliated every year at midsummer. Once the leaves return, around 4 weeks later, any over-sized leaves can be repeatedly removed as and when they are discovered, until near the end of the growing season in your climate.

Finally, keep a Field Maple fairly rootbound, the less space available for new rootgrowth, the shorter new branch growth will be.

WIRING As with all Acer species, the bark of A.campestre is very sensitive, marks easily but wiring marks also disappear relatively quickly. Field Maples also thicken relatively quickly and wire should be checked on a weekly basis to make sure it is not cutting in too hard.

Growth is surprisingly brittle; particularly that of new, green growth and care must be taken when bending branches.

PROPAGATION
Sow seed outside as soon as ripe in Autumn. Softwood cuttings in Summer, very easily air-layered in late-Spring; branches/trunks of 3-4" or more will root with ease.

PESTS AND DISEASES
Aphids, mites, scale insects, caterpillars and leaf scorch.

STYLING
The Informal broom form is closest to the species' natural habit, also suitable for all other forms except Literati. Medium to large sizes are preferable but can be grown in smaller sizes with leaf-reduction.

field maple bonsai

A massive collected Field Maple belong to Sean Stolp

Field Maple Bonsai Species Guide Page 1 2