What Kind of Pot Should I Use to Replant My Japanese Lace-leaf Maple Plant?

Containers

• A Japanese lace-leaf maple’s container can be any size or shape, according to the book "Japanese Maples: The Complete Guide to Selection and Cultivation." What matters is the pot’s material. Natural materials such as stone, terracotta, clay or wood are best for maples. Plastic containers are light and easy to move, but they stop air circulation around roots. They also get too hot in summer, need frost protection in winter and blow over in wind. The pot should be large enough to accommodate the maple’s roots, with a few inches to spare at the bottom. Avoid globe-shaped pots with small necks. When it’s time to move up a size, you’ll need to break the container to remove the tree. Wide-mouthed, deep bowls or traditional flowerpot shapes are ideal.

Planting

• Japanese lace-leaf maples prefer slightly acidic soil, such as potting mixes for the ericaceous (heather) family, rhododendrons or roses. The best potting medium combines three parts ericaceous soil with one part sharp sand. Scrub the pot with a brush and mild disinfectant and rinse completely before planting. Place a 2-inch layer of broken clay pot fragments in the bottom for drainage. Add 1 inch of stone chips. Lay 4 inches of compost over the chips. Set the maple upright in the pot, loosening outer roots to improve air circulation. Fill the pot with soil mix up to 2 inches below the rim. Lightly firm the soil as you add it, leaving the mix porous enough to allow air and water to flow. Place half of an inch of granite chips on the soil’s surface to protect the tree from slugs, snails and foraging small mammals. Soak the tree immediately.

Container Placement

• Hot sun will singe Japanese maple leaves. The Arbor Day Foundation recommends keeping a potted Japanese maple in a spot with morning sun and afternoon shade. Do not place the container next to white buildings, which reflect light and heat. However, too much shade will cause the maple’s trademark purple leaves to turn green, say plant scientists at Clemson University. Also, protect Japanese maples from drying winds and from late spring frosts. Set the container on bricks or wood slats to keep it off of the ground. Space underneath the pot boosts air circulation and drainage and keeps insects away.

General Care

• Check your potted maple daily. Container plants dry out or succumb to pest infestations quickly. Japanese lace-leaf maples need regular water, but constantly soggy soil will kill them. Don’t allow soil to dry out during summer. Potting restricts tree growth, so regular pruning is unnecessary. Remove dead inner twigs to prevent insect problems. Also, cut off branches that rub against each other, because chafing removes bark and encourages beetle infestation. Hold off on pruning until winter, when the maple goes dormant and sap stops flowing.

Pests and Problems

• Japanese maples are vulnerable to harmful insects including aphids, scales and borers. Control aphids with insecticidal soap. Scales respond to horticultural-oil sprays. Remove dead wood and protect bark to prevent borer infestations. Japanese maples also develop scorch, or dead spots between leaf veins, from too little water. Plus, maple leaves turn yellow when soil lacks nutrients. Tree scientists at the University of Florida recommend inserting manganese capsules in a maple’s trunk if it develops nutrient related leaf-yellowing.