Field maple

Fertilizing

Apply liquid fertilizer every two weeks from April through September during the growing season, or use Osmocote fertilizer cones once in April for a slow-release option throughout the season. For optimal growth, maintain consistent feeding during active growth periods. A balanced fertilizer works well for field maples, as they don't require special nutrient ratios.

The timing and frequency of fertilization is crucial for field maples - start feeding when new leaves emerge in spring and continue until late summer. Avoid fertilizing during dormancy or when the tree shows signs of stress.

Placement

Field maple bonsai thrive in full sun to partial shade locations, preferring airy spots without intense summer heat. These remarkably hardy trees can withstand temperatures down to -40°C, making them suitable for year-round outdoor growing. However, smaller specimens benefit from winter protection, particularly when temperatures drop below -10°C.

While naturally frost-hardy, potted bonsai are more vulnerable to root freezing due to the limited soil volume. Consider protecting older trees in the garden during winter, ideally under deciduous trees. For young field maple bonsai, provide frost-free, bright winter quarters as a precaution.

Pruning

The field maple's robust pruning tolerance allows for aggressive cutting back, particularly during spring or summer. Branch cutting should be done from January to February or during summer months, while leaf cutting and tweezing begins in July. This species grows quickly and coarsely, with long internodes that require constant pruning to maintain tight growth patterns.

For structural development, hard cutbacks are beneficial as the tree responds well to aggressive pruning. You can defoliate in mid-summer to reduce leaf size and encourage finer growth. The growth habit tends to be straight, making it suitable for informal upright and broom styles. When wiring, apply in May but remove within 6 weeks to prevent wire marks in the bark.

Repotting

Field maple bonsai demonstrate exceptional tolerance for root pruning, though the timing is crucial. Repot in late winter or early spring when buds begin swelling but before leaves open. Young trees need annual repotting, while mature specimens can go 2-3 years between repotting sessions.

Use a well-draining soil mix with a pH between 5-6, combining akadama, potting soil, and perlite or lava granules. When repotting, avoid aggressive root reduction and ensure the soil mix supports proper drainage while maintaining adequate moisture retention.

Watering

Water consistently throughout the growing season, with increased frequency during hot summer days - potentially multiple times daily. While field maples can tolerate drier conditions, they prefer regular watering. During winter, maintain moisture but reduce watering frequency.

The species can handle both tap water and rainwater, though it prefers the latter. Be careful not to overwater, as this can lead to root problems. Monitor soil moisture daily, watering when the top layer begins to dry but before the soil becomes completely dry.

References

Hobby Gardeners - Field Maple Bonsai Instructions Miyagi Bonsai - Field Maple Care Guide All Things Bonsai - Field Maple Care