Growing Arisaemas in Containers- Growing Jack-in-the-Pulpits or Cobra Lilies

Arisaema candidissimum
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In this article, we will discover how to grow the Arum-like plant of Arisaema in containers. I know that I discuss a wide range of plants, some well-known and widely grown, whilst others you will not find easily but still can be grown in the UK. This is one of the latter and great for those who like to grow the unusual.

Arisaema candidissimum
Arisaema candidissimum

Arisaema is a large group of flowering plants that belong to the Arum family where they are found growing naturally in China and Japan. They can also be found in South Asia, Central Africa, Mexico and in eastern areas of North Africa.

It is a woodland species and has the common name of Cobra lily in Asia countries or Jack-in-the-Pulpit for those who grow them in the west. The common name comes about because of the distinct appearance of the flowers that has an erect central spadix that appears above a spathe. This is followed by bright coloured berries that appear on the spadix in late summer.

What makes this an unusual plant is that it can change sex depending on the stage of growth. Arisaema plants are typically male when starting out but can change to female or hermaphrodite when larger. They will change sex depending on what nutrients are available or based on their genetic makeup. They will change between sexes throughout the long life of the plant.

As you can imagine they are grown for the blooms that appear under the wing-like leaves. The blooms tend to appear in late spring to early summer, where a large tubular spadix is surrounded by a spathe, giving an impression of a head of a cobra.

Find out how to grow this rhizomatous plant in containers in this article.



 GROWING ARISAEMA IN CONTAINERS

You are likely to find Arisaema sold as rhizomes. They are worth looking for but be warned they are not cheap.

Arisaema nepenthoides
Arisaema nepenthoides

First, choose a large enough container that can take 2 to 3 rhizomes. Whatever you choose make sure it has plenty of drainage holes. To this add a 1cm layer of gravel to aid with the drainage of water. To this make an enriched but free-draining growing media, which is made by mixing 80% by volume of multipurpose compost with 20% by volume of horticultural grit and a couple of handfuls of good quality manure. Add this growing media to 5cm below the top rim of the container.

Dig 15cm holes in the compost at a distance of 30cm apart from each other. Place the rhizome in each hole and then cover with more compost. Water well to allow the compost to settle around the rhizome. This is all that is required to plant Arisaemas in containers.

 CARE INSTRUCTIONS

Arisaema consanguineum
Arisaema consanguineum

Place the plants and its container, where they will get dappled sunlight but away from the bright midday sun and heat, and it will do well in a UK climate. You will need to keep the compost slightly moist throughout the growing season but never soggy. When the container starts to feel dry and light, you will need to water it but do not do so regularly but only when the plant needs it. In early spring, you will need to dress the container with a slow-release fertiliser to get it through the growing season.

In climates as in the UK, you will need to move the pot and rhizomes under the protection of a greenhouse, shed or even a garage. Place it in a cool location and cover the pot with a dark canopy with holes in them. This will allow the air to circulate and stop the rhizomes from rotting.  Water once a month until the following spring and in late May you can bring it outside once more. You will need to protect the tender new growth from hard frosts.

Once the leaves and flowers and berries die back, you will need to cut them down in late autumn.

 PESTS AND DISEASES

Arisaema does not readily suffer from diseases but the main problem is the rust fungus. The small orange dots appear on the underside of the leaves as they unfurl. Nothing can be done, except to cut the tops down close to the rhizome and discard them. The plant will not emerge until next year.

If it continues to be a problem you will need to throw the affected plants away. In poorly, aerated soils the rhizomes can get serious fungal infections caused by overwatering. Make sure that your plant is never overwatered, especially so in winter. Apart from that, they are easy to look after.

 VARIETIES TO GROW

The following varieties are recommended and available in the UK:

Arisaema candidissimum produces large striped, hooded spathes on dark green mottled stems.

Arisaema tortuosum
Arisaema tortuosum

Arisaema concinnum produces large striped, hooded spathes on dark green mottled stems.

Arisaema griffithii produces large striped, hooded spathes in dark mottles stems.

Arisaema nepenthoides produces large, pink-striped, hooded spathes on dark green stems.

Arisaema sikokianum produces markedly dark colour spadix with a large white marshmallow-like spathe at the centre.

Arisaema speciosum produces large striped, hooded spathes on dark green mottled stems.

Arisaema consanguineum produces large green hooded spathes on dark green mottled stems.

Arisaema costatum produces large brown and white striped, hooded spathes on dark green mottled stems.

Arisaema tortuosum produces long, thin, green hooded spathes on dark green mottled stems.

CONCLUSIONS

In this article, we have discussed how to grow the wonderful but not often seen rhizomes of Arisaemas in containers. They are such unusual plants to grow but produce wonderful spadix over long spathes that are often attractively coloured.

They are easy to grow, easy to care for and suffer little in the way of pests and diseases. All you need to do is protect the plant from excessive rain and harsh frosts. You would not imagine that it is that easy to grow something that exotic from a bulb.

If you have any questions or comments that you want to make on growing Arisaemas in containers, please do so in the comment box below.

Happy Arisaema growing.

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