The old-fashioned Swiss cheese plant (Monstera deliciosa) was probably the first houseplant I ever bought, in about 1970 and I seem to remember that it cost me 2 shillings and 11d. It was in 1971 that the UK changed to decimal currency – before that it was LSD – pounds, shillings and pence. There were 12 pence (pennies) to a shilling and 20 shillings to a pound. It sounds confusing but, amazingly, it was based on the Roman system where a pound of silver was divided into 240 units called dinarius (dinari) which led to the ‘d’ or pence. The plant was bought from Fine Fare, a supermarket that disappeared in the 1980s. It was a seedling plant with a few leaves with some slashes in the largest of them. It was treasured and soon produced mature leaves and, with its moss pole, soon reached the ceiling. Periodically I would cut off the top and re-root it to keep it manageable and it lived for a decade or more – though disappeared after I left home. The plant is now enjoying a well-deserved surge in popularity.
But a new monstera is challenging the old favourite. There are about 50 monstera species from the Americas and they are members of the wonderful arum family (Araceae) which contains some of the most amazing of all plants including the massive titan arum (Amorphophallus titanum) and tiny duckweed (lemna). Monstera adansonii (which is similar to and confused with M. obliqua). This is given the common name of Swiss cheese plant but also monkey mask which, while it is difficult to understand, at least differentiates it from the more traditional plant.
This is a very different plant, although the leaves also have holes, thought to be a defence against wind damage. The leaves are smaller (up to 20cm long) and narrower. They are also softer-textured and paler green and less lustrous. It can climb and produces lots of aerial roots along the stems. These are a problem in the home because they will ‘stick’ to walls, ruining paintwork (I know!). It can be trained up moss poles. But because it branches freely, especially when cut back, and has slender stems, it is also happy as a trailer. I have had my plant four years and it has been moved many times.
At first I let it trail, then I trained it up the pachira (see two days ago) and it was trained along the support bar in the conservatory (reaching about 6m long) and then I got bored and cut it right back and have been letting it trail from the top of a book case. In poor light it gets ‘stretched’ but here, near a south-facing window (but never in direct sun) it seems very happy.
One thing it won’t tolerate is overwatering and many leaves will turn yellow and drop off. But if it is ‘dried out’ and cut back, to remove bare stems, it will soon bounce back. It is easy to propagate and any sections that are removed can be rooted, trimmed just below and above a joint. It needs a minimum winter temperature of about 12c. I suspect that it needs higher humidity than the usual Swiss cheese plant but my plant is never misted – though that might be advisable in a very warm house. It certainly is a plant that would like life in a bathroom. When it comes to repotting, because a slightly acidic compost is required, a bag of ericaceous compost would be best. With most of my houseplants I try to ensure a coarse compost so I tend to sieve the compost and use the larger lumps to pot with or add in some composted bark. After all, this is a plant that needs an organic compost, growing as it does in leaf litter and partly stuck to trees.
Monkey mask is usually sold as small plants that show no signs that they could take over a room. It will require space and a fair bit of looking after, to train, prune and support, but it is a dramatic addition to a room and great fun.