Clematis acerifolia Maximowicz

Clematis of the Month for January 2022

described by Ton Hannink

C. acerifolia flower taken in February 2020

Section: Cheiropsis

Subsection: Montanae

Distribution: China: Beijing

Flowering: (April - May in the wild) but in Holland from February to March in the greenhouse.

Habitat: Rocky cliffs, soil slopes; ca. 200 m.

First Recorded: Bull. Soc. Imp. Naturalistes Moscou. 54(1): 2. 1879.

First in cultivation: In 2018 from China by Ton Hannink

The flowers of Clematis acerifolia are white or pinkish, spreading, narrowly obovate to oblong. The flowers are 5 – 7 cm across.

The leaves have the form of an Acer and are pinnate and light green. Because the leaves are small and light green the flowers are good to see on the plant in spite of the small size of the flowers.

In 2008 I got my first Clematis acerifolia from China. For me it was a completely new species and one I had never heard about before. The plant developed and survived the first months but after the first winter, the plant was dead.

In the following years, I got seeds from China again and these seeds germinated within two months. The young plants grew well but after one year the young plants stopped growing and even after two years, the plants were only 2 cm tall.

I lost most of them during the winter. I had used the same soil as I normally use for all my Clematis seedlings but I still had bad results.

I got more new seeds and these germinated very well again. The young plants grew well and I was very happy to hear from Hazel Tsang that the soil in China where this species grows is rather alkaline, with a pH > 7.5. I changed my soil and used more stones and alkaline components. Now the plants grew fast for this species. Several times I watered with sodium bicarbonate and this was good for this species.

When I had some plants that were 3 years old, I expected in Spring to see the first flowers, but in the autumn it was rather wet. I placed the wet pots in my greenhouse and this was a big mistake, all the plants died!

I started again with seeds which germinate very well, young seedlings in the right soil and alkaline water and rather dry during the winter. I also changed the pots and used high pots. Now I had some good plants and I hoped to get flowers the next year.

In 2018 during our Clematis meeting in Orléans (France), Huahecao Tian showed us the fantastic species in China. The conditions in nature is very difficult to create in our pots.

In 2019, my plant grew very well and I was very aware in the autumn to keep the plant as dry as possible. The plant became dormant and the colour of the leaves changed to brown. During the winter, there were no more leaves on the plant.

The stems were very woody and short, typical of a real rock plant, as we’d seen on the video about Clematis acerifolia in China from Huahecao Tian.

In the second week of January 2020, I saw the first big points on the top of the stems and I was wondering if I would get buds or new stems. In 2019 it had been all stems.

The points grew more and after two weeks I was sure that I was getting flowers.

In total I got 12 flowers. It is such a beautiful Clematis, with light green leaves in the form of an acer and the light pink flowers. In China we see that the flowers vary from white to pink.

Over the next few weeks I enjoyed the flowers on the plant. Then suddenly the plant died within one day.

The roots were still in good condition, so I do not know why the plant died.

Now I must start again with seed to get new plants and that is a pity!

My experiences are;

• Seeds germinate very well.
• Seedlings must grow in high pots because repotting the young plants damages the roots.
• Soil must contain alkaline stones and the pH must be higher than normal for Clematis.
• I regular water with sodium bicarbonate.
• Plants must be stored rather dry during winter.

I have still not found how to use fertilizer and the composition of the fertilizer. Must I use a fertilizer with high nitrogen or high phosphorus or high potassium? Does this species need trace elements?

Timelapse sequence of photos of C. acerifolia from bud to full flowering

12 January 2020 - C. acerifolia bud?	24 January 2020 - Yes, this looks like a C. acerifolia bud
5 February 2020 - C. acerifolia bud starts to open	7 February 2020 - The first flower of C. acerifolia
7 February 2020 - C. acerifolia flower and buds	8 February 2020 - Reverse of the flower
11 February 2020 - A pot of C. acerifolia flowers	11 February 2020 - Close-up of a flower

Ton Hannink