PGG Weekend in Belgium – Arboretum Kalmthout

This is the second post about the PGG study tour to Belgium. Please click here if you would like to read the first post. Enjoy! 🙂

Arboretum Kalmthout


Arboretum Kalmthout

The weather hadn’t improved at the start of the weekend, on Saturday we all woke to grey and misty skies. However seeing Arboretum Tervuren the day before had whetted our appetites and we were all keen to see the next two places on the list – the first being Arboretum Kalmthout.

Arboretum Kalmthout has existed for more than a century. Its history goes back to 1856, when the Antwerp nurseryman Charles Van Geert in Kalmthout started with a testing ground for his nursery in Antwerp. It remained a farm until 1952, when brothers George and Robert De Belder bought the land to make their private collective garden.

View of the lawn


Picea abies ‘Nidiformis’

Picea abies 'Nidiformis'

Under the inspiring leadership of Robert and Jelena De Belder, Arboretum Kalmthout grew into one of the most prestigious botanical collections in the world. The hundreds of new plants that they introduced were from friends and breeders around the world. They collected seeds in the wild and also selected a number of new cultivars.

In 1986 the Province of Antwerp bought the land and the management, maintenance and operation continued for more than a quarter of a century entirely in the hands of the independent association Arboretum Kalmthout. The non-profit organization in 2013 transformed into an external autonomous agency of the province of Antwerp. The future of Arboretum Kalmthout looks bright thanks to an intense collaboration with the Antwerp provincial government.

Taxodium distichum ‘Nutans’

Taxodium distichum 'Nutans'

Our guide for the day, Robrecht Van Bauwel, took us on a fascinating journey around the arboretum. His passion for the place was effervescent, you couldn’t help but be infected by his enthusiasm.

The size of the arboretum’s garden is 12.5 hectares, Robrecht explained it harbours a wealth of plants from all over the world. This includes giant rhubarbs from Brazil, prehistoric conifers from Australia, snowdrop trees from North America, colourful maple trees and cherry trees from Japan, rhododendrons and magnolias from China, Cape lilies from South Africa, cedar trees from the Atlas mountain range and many other remarkable plants.

One of the grass beds


Around 7000 different varieties are grown at the arboretum, including plants that have almost or even completely died out in the wild. The arboretum contains mostly trees and shrubs, as well as herbaceous plants. The perennials don’t grow in beds or straight rows, it’s much more relaxed – a natural tree garden with shrubs and perennials creating a layered vegetation. The whole place had an air of tranquility about it, I could quite happily have wandered round Kalmthout all day.

Hamamelis (witch hazel)


Their collection of witch hazel, hamamelis, is the largest in Europe and contains some of the oldest known varieties. Kalmthout is also the International Cultivar Registration Authority (ICRA) for the genus Hamamelis. Hamamelis x intermedia ‘Gingerbread’ and ‘Spanish Spider’ both came from Kalmthout.

It was strange seeing Hamamelis trees covered with flowers and leaves at the same time – I have only ever seen them with flowers on naked branches back home in the UK. As well as a Hamamelis festival they also have snowdrop, hellebore and tomato fairs throughout the year.

The Red Garden



The Red, Blue and White Garden areas planted with herbaceous perennials were very effective. The contrast of colour and texture, especially the grasses, worked well against the backdrop of the evergreen trees. Grey foliaged plants were also used in the red garden to give even more contrast. In total there are 220 beds to look after, I was surprised to hear how small the gardening team is – 6 full time staff with lots of volunteers.

As well as a tour of the general public areas we were also shown the private parts of the horticultural yards and workshops. They use all their own compost, the soil at Kalmthout is pure sand with no clay particles at all. As such it has been cultivated for 300 years, with lots of organic matter incorporated – 80% sand and 20% mulch.

Banana bed


There were bananas (Musa) in some of the perennial beds, which they protect by packing dried leaves in a cage around them in winter. All of the conifers date from the 1800s, which was the time the nursery started.

I noticed slight raised bumps in the ground as we were walking round the arboretum, when I enquired what they were I was told that to avoid damage to tree roots small bridges are built to walk across instead.

“Tree on Legs”


That wasn’t the only unusual thing I noticed at Kalmthout. There was a Tilia x europaea which was a very strange shape – it was called the “Tree on Legs”! It had been created by grafting 5 lime rootstocks onto a young lime tree and then once a union had formed cutting through the stem of the original tree to give the appearance of it being on 5 legs. A method I am now itching to try!

Bamboo tunnel


The massive bamboo tunnel (Phyllostachys nigra) was awesome. It was as big as a house! I noticed a few other interesting plants around the place, which were:

Prunus ‘Jacqueline’ (originated from Kalmthout)
Hydrangea paniculata ‘Unique’ and ‘Brussels Lace’ (both originated from Kalmthout)
Loropetalum chinense (Chinese fringe flower, very pretty)
Hibiscus cannabinus
Molinia caerulea
Nicandra physalodes (shoo-fly plant, Solanaceae)

Stewartia koreana

Stewartia koreana



Kalmthout wasn’t my favourite arboretum we saw over the weekend but the innovative thinking and maintenance of the whole place left me enthralled. I hope to be able to manage gardens in the future with that same unique vision and perspective that Kalmthout demonstrated so wonderfully.

If you’d like to find out more about Arboretum Kalmthout then check out their website:

17 thoughts on “PGG Weekend in Belgium – Arboretum Kalmthout

  1. A lovely visit – thank-you! Your photography is very good and despite the gloomy weather you brought out the textures and colours of the plants you saw. Such a good idea to build bridges over the roots. I suppose with such sandy soil the roots would become exposed more easily.


  2. What a fantastic place! I love trees! I used the technique of exposing the roots over rock when I did bonsai plants years ago. Right now I have a bonsai that is approximately 16 years old and is only 10 inches high! Thanks for the tour Becky! 🙂


  3. Stunning Becka! There were some amazing trees. I particularly liked the tree on legs and the one earlier whose greenery looked like a canopy and it would be difficult to keep most children from playing there… 😉 xx


  4. Pingback: PGG Weekend in Belgium – Hemelrijk | Life of a Plant Lover

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