Read a commented slot maple profile here with information about growth, leaf decoration and beautiful varieties of the Acer palmatum Dissectum group. Lots of tips about planting and slot maple care.
What are the special features of the slotted maple?
Slotted maple (Acer palmatum Dissectum) is characterized by fan-shaped, deeply slotted leaves, intense autumn color and an umbrella-like growth. The plant prefers sunny to partially shaded locations and is hardy, sensitive to cutting and easy to care for.
Profile
- Scientific name: Acer palmatum Dissectum group
- Ornamental varieties of the species: Japanese maple (Acer palmatum)
- Family: Sapindaceae
- Origin: East Asia
- Growth type: shrub
- Growth height: 100 cm to 300 cm
- Leaf: lobed, pinnately cut
- Flower: Grape
- Fruit: winged
- Roots: shallow roots
- Winter hardiness: hardy
- Use: Solitaire, potted plant
Growth
Asian Japanese maple (Acer palmatum) is the ancestor of noble ornamental varieties that are known to creative hobby gardeners as the Dissectum group. The high appreciation in this country is based on a remarkable combination of representative growth habit and colorful, slit leaves with furious autumn color. The following key growth data explain the reputation of slotted maple as a defining design component for beds and balconies:
- Growth type: deciduous, small to medium-sized shrub with deeply slitted leaves, intense autumn color, pretty flower clusters and winged fruits.
- Growth habit: umbrella-shaped, overhanging.
- Growth height: 100 cm to 300 cm
- Growth width: 150 cm to 250 cm
- Growth rate: 5 cm to 15 cm growth per year.
- Gardenically interesting properties: sensitive to cutting, otherwise easy to care for, hardy, long-lasting.
Over the years, each slot maple tree develops an unmistakable silhouette and becomes a unique floral specimen. The leading branches on the tree steadily thicken and form bizarrely intertwined shapes, predominantly in a lateral orientation.
Leaf
The slot maple's most beautiful decoration is its foliage. The following overview attempts an objective summary of the botanical facts:
- Leaf shape: palm-sized, deeply cut, 5-7-lobed, pinnate secondary lobes.
- Leaf color: fresh green, red, violet-red, dark red to black-red.
- leaf edge: serrated
- Autumn coloring: golden yellow to orange and apricot colored, fire red to scarlet.
- Arrangement: opposite
Ornamental varieties
The Dissectum group contains a variety of ornamental varieties with individual leaf colors in summer and autumn. The following table presents the top 3 of the most beautiful slot maple varieties in more detail:
| Top varieties | Red maple ‘Dissectum Garnet’ | Green Slotted Maple | Dark red maple 'Dissectum Atropurpureum' |
|---|---|---|---|
| Botanical name | Acer palmatum dissectum garnet | Acer palmatum dissectum | Acer palmatum dissectum atropurpureum |
| Leaf Color | dark purple to black-red | freshgreen | brown-red to bronze-green |
| Autumn Coloring | bright red | golden yellow to orange | fire red |
| Growth height | 100 cm to 200 cm | 100 cm to 200 cm | 300 cm to 500 cm |
| Growth width | 100 cm to 400 cm | 150 cm to 250 cm | 250 cm to 450 cm |
Bloom
As an ornamental addition to the leaf decoration, distinctive flowers appear on the maple tree in spring with these characteristics:
- flower shape: grape-like
- Flower color: reddish to purple, later brownish
- Flowering time: May and June
Pollinated Japanese maple flowers transform into winged fruits, which act as 'helicopters' in the family garden and make children's eyes light up.
Winter hardiness
In contrast to native maple species, Asian maple trees have to gradually develop their winter hardiness. An older tree in the bed is reliably hardy down to -23.7° Celsius. Young sloth maple depends on winter protection. The care instructions below explain simple and effective precautions.
Excursus
Indian Summer in balcony format
Thanks to the slotted maple, the balcony and terrace also shine in the autumnal fireworks of colors. The compact, slow growth allows the ornamental varieties of the Dissectum group to be cultivated in large containers. The correct starting size is a pot volume of 40 liters, which is adjusted over the years. The following video provides a useful summary of proper care:
Planting slot maple
The best time to plant slot maple is in spring. In this way, the shallow-rooted plant can grow well until the first frost. Careful choice of location protects the tree from risky transplanting. Good soil preparation is important before planting. Where and how to plant slot maple correctly, read here:
Location, soil, substrate
At this location a slot maple tree develops its decorative optimum:
- Sunny to semi-shady location.
- Ideally in a wind-protected, humid place near the pond.
- Normal garden soil with permeable, fresh, moist, slightly acidic soil.
- Exclusion criteria: waterlogging, compacted clay soil, drafty place with a drying wind.
In pot cultivation, please use high-quality potting soil (€12.00 on Amazon) without peat. Mix in coconut fiber to replace peat, as well as expanded clay and sand for good permeability. You can create the beneficial, slightly acidic pH value of 5.5 to 6.0 by adding a third of rhododendron soil.
Planting – tips for beds and pots
Place the potted tree in a bucket of rainwater. While the moisture soaks the root ball, devote time to preparing the bed and container planting. The best planting tips for slot maple:
- Dig up bed soil two spades deep, remove roots, stones and weeds.
- Cover the bottom of the spacious planting pit with sand or lava granules to protect against waterlogging.
- Add mature compost and horn shavings to the excavation as starting fertilizer.
- Do not plant slot maple deeper than before in the purchase container.
- The planting distance is half of the expected growth width (average 250 cm).
- Mulch the tree disc or plant with ground cover that tolerates shade and root pressure.
- Fill the pot substrate over a drainage made of pottery shards, taking into account a pouring rim.
Water the freshly planted slotted maple generously. In the following weeks, regular watering every two to three days will support rooting.
Maintaining slot maple trees
Slotted maple care is easy. Even beginners master water and nutrient supply with flying colors. A pruning is rare. Transplanting in the bed is possible at the beginning, but carries a high risk of failure later. As a container plant, the weakly growing tree needs to be repotted occasionally. Winter protection is mandatory under certain conditions. Tried-and-tested care tips for speed readers:
Pouring
- Water the garden soil and potting substrate promptly if there is noticeable dryness (finger test).
- Normal tap water, skimmed pond water or collected rainwater are suitable as irrigation water.
- Mulch the tree disc with lava mulch, compost, bark mulch or pine bark.
Fertilize
- Fertilize slot maple in the bed either in spring or autumn with compost and horn shavings.
- As an exception, do not rake in organic fertilizer, but rather sprinkle it with rain to protect the shallow roots.
- Extra tip: a potassium-focused fertilizer in August/September strengthens winter hardiness.
- Provide container plants with liquid fertilizer once a month from April to September.
Cutting
Slotted maple grows very slowly and has difficulty sprouting from old wood. These two aspects make the tree sensitive to cutting. If individual branches protrude from the crown or if dead wood accumulates, these are valid reasons for pruning. The right time is just as important as a planned cut. How to properly cut an Acer palmatum dissectum:
- Prune slotted maple in the leafless period and only when necessary.
- Sharpen and disinfect the pruning shears in advance.
- Cut off dead wood at the base, thin out inward-facing shoots.
- Restrict pruning of excessively long branches to last year's growth.
- Place the scissor blades a few millimeters above a bud or a sleeping eye.
Transplanting, repotting
In the first five years you can change the location of your maple tree. As a container plant, you should repot the tree every three years. The best time is in spring, well before budding. You can read compact instructions for the correct procedure here:
- Pick off the root ball with a spade, at least to the diameter of the crown.
- Lift the tree out of the ground, put a jute bag over the bale, plant it in the new location and slurry it in.
- Compensate for lost root mass by pruning.
- Unpot the potted plant, shake off the exhausted substrate, clean the drainage.
- Plant and water either in the existing, cleaned pot or in a new bucket.
Because no root mass is lost when repotting, pruning is unnecessary.
Wintering
In the garden soil, the shallow roots run the risk of freezing to death in winter. Simple winter protection protects the tree from frost damage, especially in the first few years. As a container plant, even an older maple tree is not completely hardy. It's worth taking a look at these winter tips:
- In the bed: Cover the root slice with plenty of autumn leaves and spruce branches.
- Overwinter the potted plant outside: cover it with several layers of fleece, jute or bubble wrap, place it on wood in a place protected from the wind in front of the house wall.
- Overwinter the potted plant indoors: before the onset of winter, move it to a frost-free winter quarters.
Popular varieties
Beyond the top varieties in our profile table, these attractive slot maple varieties can be discovered in stores:
- Sangokaku: Rarity with coral-colored bark, green leaves and golden yellow to apricot-colored autumn colors.
- Tamuke yama: 2, 50 m small slot maple with scarlet autumn color, beautiful in the pot and Japanese front garden.
- Crimson Queen: red slot maple boasts 10 cm large, dark purple-red summer leaves and bright red foliage in autumn.
- Beni-maiko: Japanese slot maple impresses with green-pink leaves in summer and scarlet to fire-red autumn leaves, compact with a height and width of 250 cm.
FAQ
My slotted maple tree in the pot has wilted leaves in the middle of summer. Why is that?
Various causes cause the leaves of a container plant to wilt in the middle of the season. Waterlogging is often responsible for the problem. Excess irrigation water cannot drain away. Root rot spreads in the permanently wet soil. The foliage is no longer cared for and wilts. A hot, sunny location with a drying wind is also a common trigger. The slot maple comes under drought stress and pulls in its leaves.
My Acer palmatum 'Dissectum' loses all its leaves at the end of October. Is this normal?
Slotted maple is a deciduous tree. Following a magnificent autumn color, the plant sheds its leaves. This is no cause for alarm. Rather, it is a natural process. Next spring your Acer palmatum 'Dissectum' will sprout again.
Can a slot maple tree overwinter outside as a container plant?
With appropriate winter protection there is nothing wrong with it. Place the bucket in front of the house wall or in a wall niche protected from the wind. A wooden base protects against frost from below. Cover the container thickly with winter fleece, jute ribbons or a potato sack. The root disc receives a mulching layer of leaves, bark mulch or straw. Do not allow the substrate to dry out. From October to March you stop supplying nutrients.
