Plant of the month

Ginkgo biloba 'Beijing Gold'

Of the Japanese nut trees Ginkgo biloba, is without doubt a spectacular new introduction. In the spring the leaves come out in golden yellow to become a variegated colour later in the summer. On the green leaf there appear more or less radial white stripes in the leaf. The autumn colour is butter yellow.

This cultivated plant received a 'Getuigschrift van Aanbebeling' (Certificate of Recommendation) from the inspection committee of the Koninklijk Verbond van Boskoopse Culture!

• Seedlings from the earth, size 60/80
• Price: 15 euros
• Order your own one right away.           

Acer shirasawanum 'Aureum'

The Japanese dendrologist Miho Shirasawa gave his name to this type of maple tree that is closely related to Acer japonicum. The yellow-leaved form of this Japanese maple is one of the most spectacular garden plants, but is rarely planted in gardens however. The ‘Fullmoon Maple’ – as it is called in English - has an 11-lobed, 5 to 11 cm large leaf In the spring the leaf is yellow-green, after which it gets a little darker but the yellow tint remains dominant. The upright fruits are first green but quickly change their colour to red. In the autumn the leaf is coloured orange to red.

This Japanese maple initially grows reasonably quickly, but after that the growth slows down. The habitus is very special in that the ends of the branches on this beautiful loner have a layered structure. Very old plants can eventually grow 4 to 5 metres high. Beautiful examples are in the maple avenue in the arboretum garden.

• Beautiful single plants in 14 litre pot, size 60/80
• Price: 85 euros
• Order your own one right away.         

Agapanthus 'Sunfield'

This South African autumn lily is a real eye-catcher in the garden. The cobalt blue flowers in up to 20 cm large many-flowered cymes grow on a good 1 metre high strong stem and attract the attention from afar. This bloom rich selection was introduced in 1987 by the Zonneveld brothers in Heemskerk, the Netherlands. The plants are deciduous, so they can not only be used as pot plants, but can also be planted in the ground. A sunny and well-draining location and a thick layer of compost and leaves during the frosty periods guarantee yearlong garden pleasure. These cultivated varieties flower in July and August.

• Heavy and well-flowering plants in 7.5 litre pot, size 120/130
• Price: 18 euros    
• Order your own one right away.  

Rhodochiton atrosanguineum

The family Rhodochiton originated from Mexico and consists of evergreen climbing plants. Rhodochiton atrosanguineum flowers from spring until the first frost. The hanging flowers have a long dark purple flower tube; the clock-shaped flowers are dark purple-pink. This plant is ideal for covering fences, barriers, pergolas and the like. In a rich nourishing location in the sun to half shadow they quickly grow to 2 or 3 metres in height. Sufficient moisture is important. It is an annual plant that you can keep as a pot plant. It is also easy to propagate from seeds.
You can also use them as hanging plants on a balcony, for example.

• Flowering plants in 19 cm pots, size 60/70
• Price €11  

Rhododendron sinogrande x Rhododendron ‘Madame Augere’

This remarkable, promising hybrid has been created by Leon De Clerq, a well-known specialist in Hardy Ghent Azaleas.

Rhododendron sinograndeis a wild variety from the Chinese province of Yunnan. This rhododendron is really striking thanks to its especially large leaves that can grow to up to 50 to 90 centimetres long. It is one of the tree rhododendrons that grow up to 10 metres high. The flowers are creamy white with a striking carmine-coloured patch. Unfortunately Rhododendron sinogrande  is not hardy enough for our climate.

Rhododendron ‘Madame Augere’ has clusters of deep red flowers and is evergreen and hardy.

The hybrid of these two plants on offer has some of the qualities of both parents and is suitable for our gardens. The flowers are salmon pink in colour and appear in March and April.

Plants in 20 litre container, size 50/60  
Price €30

In 2006 exclusive Wollemi Pine was available from the "launch edition" at the Arboretum Kalmthout. This year we have wonderful plants again from the "standard edition". This means that we can apply other prices and make these special plants available also to the more average gardener. 

Your own Wollemi Pine, as of 97 euros.

There are plants of 30 cm in height in a protective sheath, they cost 97 euros.
It includes:

• a DVD
• a booklet with care tips      

There are plants of 60 cm in height in a wooden frame, they cost 395 euros.
It includes:

• a DVD 
• a numbered certificate
• a booklet with care tips      

You can pick up your specimen at the plant centre of Arboretum Kalmthout, but it can also be delivered to your home. 

More information

More information about the Wollemia nobilis is available on the official Australian website. 

Dahlia

Dahlias have become popular again in the last few years. The first Dahlias arrived in Europe in about 1615 and thanks to a great deal of selection work some 20,000 different varieties of this colourful genus have been developed. At the beginning of the 20th century there were many dahlia growers in Belgium.

Dahlias form tubers that must be kept free of frost. At the beginning of May they can be planted in a sunny, well-drained position, with the necessary organic fertilizers and a pH of between 6 and 7. The soil must be moist and on very hot summer days a little extra watering is essential.
Dahlias flower continuously throughout the summer until the first frost. Dead-heading encourages the growth of new buds. Dahlias make a good basis for a summer bouquet.
After the first frost the leaves are cut off and before the soil really starts to freeze the tubers are dug up, rinsed with a hose and then dried.
They are then put in crates, covered with slightly damp peat dust and placed in a cool, dark, draught-free room. Don't forget to add the necessary name labels.

We have the following new varieties from the ‘Gold Medal’ series:

• ‘Maxime’: red with yellow edge
• ‘Chianti’: pastel pink with dark stem
• ‘Hy Pimento’: yellow with red streaks
• ‘Coccinea’: cherry red, the original colour of the dahlia  

we also have these other Dahlias:

• ‘Café au Lait’: giant dahlia cream
• ‘Kelvin Floodlight’: giant dahlia yellow
• ‘Kenora Macob’: dark red
• ‘Aloha’: yellow with red tips
• ‘Jeanne d’Arc’: pink/cream
• ‘Jura’: purplish pink
• ‘Bora Bora’: pinkish red with yellow centre
• ‘Peaches and Cream’: yellow and orange
• ‘Garden Princess’: salmon pink
• ‘Bishop of Llandaff’: red with dark leaves
• ‘Wittem’: white with purple
• ‘Floorinoor’: anemone, purplish pink/orange
• ‘Que Sera’: anemone white with lilac
• ‘Marie’/’Fantastica’: frill dark red
• ‘Etoile’: light yellow, star-shaped flower with 8 narrow petals  

The Dahlia tubers are top quality, individually packaged with a colour photo. 

Price:  2 euros, 2.75 euros and 3 euros per pack. (discounts for larger quantities)

Daphne mezereum f. alba

Compared to the common daphne,  Daphne mezereum, the variety with white flowers offers many advantages. This long flowering, deciduous winter-flowering plant is rarely cultivated and a garden plant that deserves to be better known. Of course, the most striking difference is the colour of the flowers, but the flowering season also lasts almost four months longer, from the end of November to April. The white version grows into a thick-branched shrub with all its twigs full of flowers followed by yellow berries. 
Of all well-known winter-flowering plants, the white daphne is probably the longest flowering garden plant. It needs to be planted in a partially shaded position and likes lime in the soil. The plant is very hardy. In very sunny and hot weather during June and July, the leaves may be scorched by the sun and the plant needs to be protected a little. A fully-grown shrub is about 1 metre high and 1 metre wide.
A large consignment of plants is in stock so that this brilliant garden plant can be spread more widely. They are grown from seeds collected from an older plant that has been growing and flowering in the garden of Johan Possemiers for years.

Seed plants in 1.5 litre pot
Price: per item 12 euros, per 3 plants 32 euros, per 5 plants 48 euros

Poncirus trifoliata

Poncirus trifoliata

Poncirus is the only hardy citrus family. It has only 1 variety (monotypical): Poncirus trifoliata. It is a deciduous shrub with a ternate leaf. The branches are green and set with thick thorns.   It grows best in a sunny, fairly sheltered position. The soil is rich in humus and lime-free.

The 'Japanese Bitter Orange' grows to a maximum height of 4m. It flowers in May and June with quite fragrant white blossoms. Shortly afterwards the green lemons appear, which change to a fine yellow in the autumn. These lemons are not edible but are highly decorative and give off a strong aroma.

Plants in 7.5l container, size 80/90  
Prijs €8

Plants in 2l container, size 40/50  
Prijs €5

Quercus rysophylla 'Maya'

Quercus rysophylla 'Maya'

Quercus rysophylla  is an evergreen oak that originates from the Sierra Nuevo in north east Mexico. This variety of oak has shiny, elliptical leaves up to 20 cm in size a bit like those of the Eriobotrya japonica, hence the name “Loquat Leaf Oak”.

Contrary to what you would expect of plants originating from this area, it is very hardy. This selected seedling is obviously the result of natural hybridisation with another variety. This oak grows very fast and the young shoot has brown to reddish-purple coloured leaves.

Quercus rysophylla  ‘Maya’ is a healthy, disease-free tree that grows to about 8 m high. This evergreen oak is a very valuable addition to the arboricultural range. This problem-free evergreen oak deserves a bright future in towns and cities. This oak was selected by tree nursery BILOBA en Bömer from Zundert in the Netherlands.

Grafted plants in a 2-litre pot, size 60/70  
Price: €22

Hydrangea paniculata 'Pinky-Winky'

Hydrangea paniculata 'Pinky-Winky'

This is definitely the best of all known cultivated varieties of hydrangea paniculata that change colour to pink. Give this shrub a place in the sun and each autumn the panicles will turn dark pink. If it is not pruned it will grow to about 2 m high. Like all hydrangea paniculatas, this selection is virtually disease-free. It can be pruned in the spring. It is a Belgian selection from BEST-Select.

Plants from 60 cm high, 3 litre container, price: €10.

Ficus carica 'Del Portogallo'

Ficus carica 'Del Portogallo'

The hot month of July is an excellent excuse to promote a variety of fig that is sure to bear fruit. Fig trees come from the Mediterranean where the fruit has been eaten since ancient times. There are a total of 750 different varieties, but only a limited number produce figs that can ripen in our climate.
The large, deeply carved leaves of fig trees are highly decorative. Figs need a sunny, well-drained position. The soil should be limy and rather low in nutrients so that as not to encourage too much growth..
In the south the flowers are pollinated by a small fig wasp, which unfortunately does not happen in Belgium and the Netherlands. So there are several parthenocarpic varieties to produce fruit. Parthenocarpic plants are plants that produce fruit without pollination and fertilization. An additional advantage of this is the fact that the fruits do not contain any stones. 

Ficus carica 'Del Portogallo' is a variety that is highly suitable for an urban garden. The large fruits can weigh almost 100 grams each. The first crop ripens at the beginning of July and is often followed by a second in September. We have fine plants with figs for €10.  

Echinacea purpurea

Echinacea purpurea

The cone flower belongs to the composite family and grows on dry ground in the prairies in the east of North America. The plant grows upwards to a height of about 1 m and the leaves feel rough to the touch. The flowers are reddish-purple and sometimes white, and nowadays there are even some yellow and orange cultivated varieties. They flower for a very long period from the end of June to the end of September, with new flowers each time.
During flowering the flower changes shape noticeably. At first the petals stand upright and the receptacle is flat. Then the receptacle takes on a cone shape and the petals begin to droop more. Because of this in America it is also called the coneflower.
Echinacea purpurea is one of the best butterfly-attracting plants and must be planted in full sunlight. They like well-drained gardens and are highly resistant to drought. They do not like a high groundwater level. It is recommended that every 5 years the plants are dug up and divided, the soil refertilized and they are then replanted. Spontaneous seedlings grow easily.
Coneflowers flower beautifully and for a very long time as well as making excellent cut flowers. At the end of the season the flower cones can be used in bouquets of dried flowers. Echinacea has important medicinal properties, including boosting the immune system.  
At the Plant centre we have heavily flowering plants 1 m high. Price €4, for 10 plants €36.  

Agapanthus 'Intermedius'

Agapanthus 'Intermedius'

Agapanthus has various names in English: African Lily, Lily of the Nile, Flower of Love and so on. We now have an interesting cultivated variety: Agapanthus 'Intermedius' in the plant centre. It is an old selection that has been used for the cultivation of cut flowers amongst other purposes. The flowers stand on a 60 cm high stalk and are very dark bluish-purple. The average size of the cluster of flowers is 14 cm and it contains about 50 blooms. It flowers in July and August. The seed capsules change colour to bluish-black when they are ripe. This Agapanthus is deciduous and, provided that it is well-covered, can stay in the ground in the winter in a sunny position in fertile soil. 

We have 3-year-old plants, with buds, grown in 3.5 litre pots.
Price €9.  

Fagus sylvatica 'Black Swan'

Fagus sylvatica 'Black Swan'

Out of all the native trees, beeches are among the most impressive park and forest trees. If they have enough room, in a good location they can grow into majestic trees 30 m high with a crown measuring 20 m on average.
In built-up towns and cities there is now little room for these tall, impressive trees. So, to mark Park Day 2006, the plant centre at Arboretum Kalmthout is offering a particularly fine park tree: the red weeping beech Fagus sylvatica 'Black Swan'. 

The name of the cultivated variety 'Black Swan' reflects 2 characteristics of this beech. "Black" refers to the reddish purple to purplish-black leaves - it has the darkest leaves of all the red beeches. "Swan" relates to the special shape of the top shoot. This goes straight up then bends back down so that the shoot ends up in the shape of a swan's neck. The next year a new top shoot appears that is the same shape as the one from the previous year but grows a bit higher. All the branches of this beech are very close to each other and hang down at an angle.
The tree was selected by Mr Van den Oever in the Netherlands 30 years ago. Although there are not any fully-grown specimens yet, this tree will probably grow to a height of 25 m. The autumn colour is golden bronze to orange and purple.

Plants from 1.75 m, grown in 7.5 litre pot: €35.  

Pauwlonia fortunei ‘Fast Blue’

Pauwlonia fortunei  is very similar to the well-known Chinese Empress tree (Pauwlonia tomentosa). As its name suggests, It is a Chinese tree that grows up to 12 m high and has leaves measuring 20 cm. 

In the early spring the fragrant 8 cm long bell-shaped flowers open in upright bunches even before the leaves appear. The colour varies from off-white to mauve with a purple-speckled centre. The chosen cultivated variety ‘Fast Blue’ is a new French selection. This type is different from the normal variety due to its pyramid-shaped growth and its ease of flowering as a young plant. So it is ideal for gardeners with little space and little patience.

We have young trees measuring 200/250 grown in a 15-litre pot. Price: €70.