Korean fir: varieties, plants & common diseases
Striking cones and a beautiful growth make the Korean fir a special eye-catcher. The diversity of varieties means that something can be found for a range of different garden situations.
The Korean fir (Abies koreana) delights with its picturesque growth and stands out clearly from other pine plants (Pinaceae). You can even plant this attractive plant on the balcony or terrace, because the wide range of varieties also includes small varieties that fit in a tub. In the following article we introduce the evergreen Korean fir, show its most beautiful varieties and the most common diseases.
Contents
Korean fir: Origin and characteristics
The Korean fir, which originates from the mountain forests of South Korea, grows typically for conifers with strictly acrotonic branching and therefore in a symmetrical conical growth typical of firs. Its branches stand out horizontally and in tiers, the needles are coloured a beautiful dark green. The young twigs of the Korean fir have hairy bark, which is covered by shiny, olive-brown bark on old shoots. Between May and June the female, purple flowers open, i.e. the cones, which have a cylindrical shape and consist of numerous seed scales. The male Korean fir cones are yellow and inconspicuous. What makes Korean firs so popular are their striking female cones. These grow up to 7 cm long and are a wonderful sight due to their dark blue colour with yellow-brown top scales. With age, the pine cones become dark purple to brown and covered in resin. Compared to other fir species, the Korean fir sets cones very early. This means young trees just 1 m high can already form beautiful pine cones. The annual growth is up to 40 cm, depending on the variety. Over time, the Korean fir can reach a considerable height of between 10 and 20 metres. However, it takes up to 20 years until it is fully grown. How big the Korean fir actually grows depends very much on the location, the variety and the care. The Korean fir is a very robust ornamental shrub that can withstand temperatures as low as -26 °C. Young needles can be damaged, but usually recover quickly.
Abies koreana: The most beautiful varieties
There are flat dwarf forms, compact conical shapes and sprawling giant forms of the Korean fir with purple, silvery, grey-blue and yellow-golden needles. Below we present the most beautiful Korean fir varieties.
- Abies koreana ‘Molli’: The Korean fir ‘Molli’ has beautiful, glossy green needles with a white underside. Its growth is conical, compact and it reaches a height of between 2 and 2.5 m.
- Abies koreana ‘Oberon’: The needles of this cultivar are rather short and dark green. Its growth is broad and compact. With a maximum height of 50 cm and a width of 80 cm, the Korean fir ‘Oberon’ is ideal for container cultivation.
- Abies koreana ‘Aurea’: This cultivar has yellow-green coloured needles. Its growth habit is pyramidal and conical. It reaches a growth height of about 5 m and a width of 2 m.
- Abies koreana ‘Silver Curl’: ‘Silver Curl’ features impressive dark green shiny needles. It has a columnar, slender growth habit and reaches a height of about 5 m.
Tip: Korean firs can be bought as seedlings. Grafted Korean firs bear cones earlier, but they are often less numerous. The Korean fir seedlings need several years before the first cones appear, but then they tend to produce more of them.
Planting and caring for the Korean Fir
A sheltered and sunny to semi-shady location is ideal for the Korean fir. Heat, drought and deep shade are tolerated, but result in significantly stunted growth and the Korean fir is thus less effective. The best time for planting conifers is in October. Due to the mild temperatures and increased rainfall, roots are formed intensively in the autumn months. The fir plant grows best in a cool, moist and nutrient-rich soil. If you have a garden soil that is not very fertile: Our peat-free Plantura Organic All Purpose Compost, for example, offers an ideal nutrient composition for vigorous growth of the Korean fir. Due to the wood fibres it contains, it is particularly permeable and the fine roots find it easier to penetrate the substrate.
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Planting and caring for the Korean fir in the garden
First clean the soil from weeds, stones and roots. Heavy soils are best mixed with a little sand. By mixing in mature compost or moderately nutrient-rich potting soil, the Korean fir already has valuable nutrients and good soil conditions available immediately after planting. The planting hole should be twice as deep as the root ball. As the Korean fir is a deep rooter, it needs plenty of space between its neighbours so that the roots can spread unhindered. In the border, the dwarf form of the Korean fir requires about 0.5 to 2 m² and large varieties between 2 and 4 m² of space. A layer of mulch ensures that the soil does not dry out. In the bed you should fertilise the Korean fir twice a year between March and July, depending on the location. On very acidic soils, a magnesium deficiency can occur, leading to brown discoloured needles. Therefore, a high magnesium content in the fertiliser is advantageous.
Planting and caring for the Korean fir in a tub
Small-growing varieties of the Korean fir can be cultivated in tubs without any problems. For cultivation in a tub, choose a container that is at least 45 cm wide. The substrate should never dry out completely. A drainage layer prevents waterlogging. Due to the low supply of nutrients in the container, the Korean fir has an increased need for fertiliser. Fertilisation should take place every fortnight. The ideal fertiliser for this is granulated fertiliser, which you spread under the mulch. It is best to renew or top up the mulch layer regularly. The Korean fir also looks good in a tub as a Christmas tree and spreads a cosy Christmas atmosphere with a little decoration.
Common diseases and pests
Infestation with herpotrichia brown felt blight leads to a distinct brown colouration of the needles. The needles are overgrown by a light brown fungal mycelium. As a preventive measure, a narrow, damp and windless location should be avoided. Infestation by aphid usually occurs in spring. Older branches in the interior of the Korean fir are particularly affected. Beneficial insects such as ichneumon wasp or ladybirds can provide relief in the event of a pest infestation. However, this does not work so well outdoors. Here you can use control agents such as soap suds or nettle broth and spray the plant with them. Another disease of the Korean fir is Sirococcus blight. The fungus occurs mainly on the young shoots and causes the needles to die and the branches to become crooked. It is best to remove infested material, avoid damp places and check the nutrient supply. In some locations, fertilisation with calcium and magnesium can lead to an improvement.
Propagation
Propagation of the Korean fir via side shoots is not suitable because the shoots grow horizontally. If a Korean fir grows with multiple tips, an attempt at propagation via terminal cuttings can be made. The Korean fir can be propagated by seed, but this method is very demanding and rarely leads to success, as the Korean fir is a cold germinator. If you still want to attempt it, you can proceed as follows:
- Soak seeds in water for 48 hours
- Drain and place in a plastic bag with a few spoonfuls of sand
- Store in the refrigerator for 3 weeks
- Sow seeds at temperatures around 15 °C and cover with a thin layer of soil
- Seedlings appear after 3 – 4 weeks
- Transplant in the second year between March and July
Are Korean firs poisonous?
In principle, the Korean fir is slightly poisonous to humans. When eaten by pets, poisoning symptoms such as diarrhoea can occur, because firs form a broad arsenal of defensive substances against predators.
