How to Grow Japanese Maple
Japanese maples have thin bark easily damaged by impacts from lawn mower decks, string trimmers, or other objects. Mulching around the base will keep the lawnmower away and moderate soil moisture swings.
Fertilization is not typically needed. However, if desired, apply a slow-release blend designed for trees and shrubs in spring. Avoid fertilizing in the fall, as the new growth may not harden off in time for winter weather.
How to Prune Japanese Maple
Pruning for aesthetic reasons can be done at any time of year. However, late winter is the least intrusive for the plant. Remove crossed or twisted branches, dead or wounded stems, and gangly long branches.
Watering
In general, Japanese maples have shallow roots, so they appreciate a cool, evenly moist but well-draining site. Consistent moisture is key.
A light covering of mulch can help to conserve moisture, but keep the mulch away from the trunk. A newly planted Japanese maple should be watered thoroughly over the first few days to eliminate air pockets and settle the soil. Make sure that the area is well-draining so that the roots do not sit in water (the plants do not like wet “feet”). After that, they’ll need to be watered regularly.
Sandy or loamy soils may need water about every 2 to 4 days, while clay soils may require less frequency. Once trees become established, give the tree about 1.5 to 2.0 inches of water about every week or so, or when the soil becomes dry about 3 inches below the surface. During hot/dry spells, water slowly but deeply so that it reaches the top 12 inches of soil. When the leaves drop in fall, water once per month until the ground freezes.
How to Propagate Japanese Maples
Japanese maples can be grown from seed, although germination can be spotty. Collect seeds in autumn. Winter sow or cold stratify for 3 to 5 months. If the seeds were dry when gathered, soak them in warm water for 24 to 48 hours, then winter sow or cold stratify.
Gather cuttings when this year’s growth has changed from soft and fleshy to firm and dense. You’ll want to cut from new growth. Check about a month after your last frost date when the leaves are fully out. Some cultivars root more reliably than others.
If possible, take cuttings from young trees—they root much more reliably. If you must use stock from an older tree, stick more cuttings to compensate for the lower success rate. Keep cuttings in water until ready to stick—don’t allow them to dry out once cut.
- Take cuttings 6 to 8 inches long and cut just below a node. Ideally, there will be two to three nodes on the stem.
- Strip lower leaves and scrape the bottom 1–2 inches of the cutting with a knife’s edge.
- Dip the bottom a few inches in 1- to 2%-strength IBA powder or solution.
- Use a pencil to poke holes in the growing medium, stick the cuttings about 2 inches deep, and firm the soil around them. A mixture of equal parts coco coir and perlite works well.
- Japanese maple cuttings will need to be misted. If you don’t have a timed mist system (most of us don’t), you can imitate one with a humidity dome or a plastic bag and frequent misting with a spray bottle.
- Don’t let the plastic touch the leaves. Use sticks or pencils to prop up the sides. The goal is for the leaf surface to stay moist and not dry out.
- Supplemental lighting after rooting (6-8 weeks) can induce a growth flush.
- Leave rooted cuttings undisturbed through the following winter dormant period.
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