Within the Araceae family of some one hundred genera of Aroids, Arisaemas have become increasingly popular with monocot growers. The two hundred and fifty species of Arisaemas, also known as Cobra Lillies, are found in temperate and also tropical areas in the Himalayas, China, Japan and to a much lesser extent in North and Central America. As the plant height within the species varies from one to six feet the intention is to discuss some that range up to twenty four inches and can be adequately accommondated in a two to three litre plastic long tom pot.

Our collection of thirty plus species were selected with size in mind as well as winter hardiness. Photos of three are shown here. A further and important consideration is that they present few difficulties in cultivation. All attempts to grow the sub-tropical species under our conditions have been given up as it was a wasted effort even if planted late, just prior to dormancy ending. Some species produce offsets causing a sense of anticipation at the time for depotting. Arisaema candidissima, Arisaema amurense, Arisaema tripyhllum and Arisaema ringens are in this category. To grow from seed for those species that do not produce offsets is easy, with quite high germination results with a good proportion getting through the first two years before being potted on. With the later flowering forms the plants die down whilst the large seed heads are still green and a considerable time elapses before the seed ripens.

When grown in pots for display purposes the limitations put on the plants must be borne in mind, such as the lack of an open root run, the varying temperatures placed on the root system by just being in a pot and the necessity to feed the plants more frequently than when in the garden. All of these drawbacks are eliminated when they are grown outside. Very free drainage is required under the tubors whether in the open garden or in a pot. We use John Innes No. 2 and a horticultural grit in equal measure under the tubers and reduce the grit to a third above the tubers. We still have some losses, not confined to a particular species. The general opinion is that excess moisture added to low temperatures during the dormancy could be the reason.

Arisaema sikokianum (left) prefers partial shade, Arisaema serratum (top centre), one of the taller species we grow, is some twenty four inches tall when pot grown but can be taller in the open. It comes from the mountainous regions of northern China and Japan and needs a more moist, organic, gritty compost and when grown outside requires more shade combined with a fairly humus rich, open soil. This one flowers early in the spring. White stripes on a glossy green background make up the colour of the hooded spathe.

Arisaema cilatum (below) flowers later with us, usually in early July. An asiatic has similar foliage to Arisaema consanguineum. The spathe is brown and growing conditions match those for Arisaema serratum.

By John Morris