‘Crimson King’ Norway Maple (Acer platanoides ‘Crimson King’)

Norway maple ‘Crimson King’ is a Norway maple cultivar, bred in Belgium in 1937 from a ‘Schwedleri’ seedling. Its distinct feature is that it keeps its maroon color throughout the season and turns reddish-orange in the autumn. The flowers are maroon yellow, and the fruit is purplish. Norway maple ‘Crimson King’ is considered the most vigorous red-leafed maple

I. Appearance and Characteristics

An intensely coloured seedling variety of the Norway maple, Acer platanoides Crimson King is a medium-sized to tall deciduous tree with deep purple-crimson, glossy, five-lobed leaves. Pinkish-orange flowers on the leafless branches in April turn to double-winged, sycamore-like fruit (samaras) in Autumn. A vigorous, fairly fast-growing tree with a symmetrical spreading shape, it is very hardy and wind-resistant, and a good choice for colder areas. It also tolerates city pollution.

II. How to Grow and Care

Sunlight

A ‘Crimson King’ Norway Maple can tolerate full to part shade but will perform best in full sun. You will notice the best colors and most foliage if the tree is located in an area with at least six hours of indirect sunlight daily. If placed in the part shade, there will not be any major health issues, but you will notice a definite fall off in vibrance and foliage.

Temperature and Humidity

The ‘Crimson King’ Norway Maple is a non-native that has naturalized throughout the Northeast and upper midwest of the United States. It thrives in the temperate climates found in those locales and does not do well in areas that get much warmer or cooler.

During winter, its relatively weak wood is prone to breakage under ice and wind stress. In the summer, high heat combined with harsh sun and high winds can lead to leaf scorch. Being so vulnerable to issues caused by temperature means that the Crimson King Norway maple should stay safely put within its recommended USDA habitable zone.

Watering

Once established, ‘Crimson King’ Norway Maple do not require supplemental irrigation and will do fine even in drought conditions. Getting the tree to that point will take some routine watering, but it is not a chore you need to be obsessive about like you would with many ornamental trees. Giving the ground around it one good soaking a week for the first season or two should be plenty to get it on its way to being a happy and healthy tree.

Soil

One of the things that makes the ‘Crimson King’ Norway Maple so problematic is how easily it spreads and thrives. That has a lot to do with the fact that it tolerates a wide range of soils. If the soil is fairly average, has medium moisture, and drains well, Acer platanoides ‘Crimson King’ will thrive. The only soil where it will have a tough time is poor draining soil.

Fertilizing

Elevate ‘Crimson King’ Norway Maple’ ‘s vigor with balanced nutrition fertilizers, ideally in spring. A high-nitrogen variant may encourage robust foliar displays. Annually, a modest quantity suffices. Fertilization promotes healthy growth and resilience. Adjust fertilization with growth stages and seasons. Over-feeding risks harm; follow label rates. Practical tip: apply when the soil is moist, not dry or waterlogged, for optimal uptake. Always integrate fertilizer evenly around the drip line, not at the trunk base.

Planting Instructions

The best time for planting or transplanting a norway maple ‘Crimson King’ is following defoliation in the fall. At this time, the leaves will have fallen off so there is little transpiration and water loss can be avoided. In addition, the root system will still be growing at this time, preparing for regrowth the following spring. Transplanting should be avoided on the coldest days because cold wind can kill some of the shoots and branches. During the winter, in areas that cannot be sheltered from the wind, it is recommended to cover the branches.

Pruning

Pruning a healthy Crimson King Norway maple is not necessary. If your tree is thriving, has a good form (single main leader), and has no damaged branches, it can be left alone. If the need should arise, the best time to prune a Crimson King Norway maple is winter or early spring when the tree is still dormant.

Propagation

There are a few quick and easy methods of propagating a Crimson King Norway maple. The easiest is to find a re-seeded seedling, transplant it into a pot, and allow it to develop a heartier root system until you are ready to transplant it at its permanent location. The second is almost as easy; it requires more time and effort. This method will have you collect the samaras (helicopters) and remove the wings to expose the seed.

Plant the seed in a pot of moist soil or starting medium, keep it moist for a few months, and wait. To ensure success, plant more than one, as you may not get 100% germination. Allow the seedlings to develop a healthy root system in the pot, and then transplant them to their final location, and you are all set.

Pests and Diseases

Besides their invasiveness, another reason why Norway maples are often avoided is their tendency to be bothered by disease. The various root rots are the most serious diseases and types that can cause the most damage to property and cause serious injury if not remedied. With root rot prevention is key, the Norway maple suffers from three varieties, Fomes root rot, Ganoderma root rot, and Laetiporus root rot, each having different symptoms.

With Fomes root rot, you will notice a structure that is shaped somewhat like a hoof, the color will be grey, and it will be roughly about six inches long or so, growing yearly. As the disease progresses, branches will start to decay and drop, which is where the danger exists.

Ganoderma root rot is a devastating disease that will first appear as shelf-like fungi that might appear as one or a cluster that will overlap. The fungi will be an ochre color with cream borders and be roughly a foot in length. Once infected, the branches will start to die, and then eventually, so will the entire tree.

Finally, the symptoms of Laetiporus root rot will present with huge clusters of vividly colored orange shelf-like fungi that form during the late summer through early autumn. These masses will harden and fall off during the cold winter months to only form the following year again.

Sadly with all three of these diseases, once the symptoms are seen, the damage is already done, and the tree cannot be saved. Dead branches should be removed, and eventually, the entire tree, as it will, in time, fall, and it is better to have it fall on your terms than randomly, possibly injuring someone or damaging property.

Preventing root rot of all types is best done by not overwatering and planting in areas with adequate drainage.

III. Uses and Benefits

It is well-adapted to street tree use but due to its bold leaf color may produce an overpowering, negative effect if planted along an entire street. It is probably best used as a shade tree or specimen or in a group tree planting to add accent to an area. Many types of birds are known to use the seeds as a food source, so it might be best located away from an area with park benches.