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Arisaema Quick Guide

The information written here is based on my experience and what I have read. I am in the early stages of my collection. Good luck with your collection and please do share your experiences with me.

Early to Flower:  intermedium, kiushianum, nepenthoides, serratum, serratum mayebarae, sikokianum, thunbergii urashima and triphyllum.

Early Summer Flowering: costatum, fargesii, ringens, tortuosum.

Later to flower: candidissimum, consanguineum

Arisaema can change sex multiple times during their lifespan. The larger the plant material the more likely it is to be female and the smaller it is it will be male. Of course some are bisexual.

Most require shade but some tolerate sun ie A. Consanguineum, A. Costatum have done very well in full sun although it is not recommended.

Biggest danger is getting too wet before they develop foliage and sometimes later. You risk losing  your prize  plant. I have lost quite a few this year, 2021, and continually Arisaema, so please be very careful. Now March 2023 I have lost 45. I do water before growth appears but lightly around the edge of the pot if the compost looks very dry. Best to use a light and airy compost or add loads of sand, grit or perlite. Once the foliage begins to fade cease all watering for pot plants and keep them somewhere frost free over winter. For ones in the ground make sure there is good drainage. I have A. Costatum that has been in the ground for 10 years with no issues.

Their Spathe/Inflorescence/Coloured bract come in a range of colours and all are streaked/patternated and most impressive. At first I thought Nepenthoides was quite drab by comparison to Sikokianum which is beyond impressive but I have changed my mind. All the Arisaema I have are amazing. In 2022 I have 29 species plus a seed of A. Cucculatum, which I sowed in January 2021, germinating in Feb22. I now have 41 species and sub-species, March 2023, and over 300 in total.

Most have an appendage to the Spathe, Spadix or leaves of varying lengths. A. Intermedium also has a very long appendage to the Spadix. I measured one at over 80cm.

The rhizome/corm/bulb is actually a modified subterranean stem and are usually referred to as one of the former depending on their shape.

At the end of the season check for offsets and the condition of the modified stem. I use my finger in the centre of the pot and gradually push my finger down and spiral out slightly until you touch the modified stem checking for offsets. This year 2022 I have found 41 offsets which I have potted on. They are of various sizes and the larger they are the more likely they are to flower the following season and to be female. Check the parent plant for rot and if present cut it off. Whether you decide to remove the modified stem and store it over winter will be up to you. I have not gone down that root yet. I will be fluffing up the soil leaving the modified stem in the pot and I check them 2 to 3 times over winter. The roots do fade away when the foliage dies back which I assume will help to prevent rotting. They will grow again from spring onwards. 

A. Flavum is the shortist upto 40cm ( short form ) and A. Tortuosum the tallest upto 180cm.

Fungas gnats do a lot of the pollinating and you find a slit at the bottom of the Spathe then you will have a male. This allows the gnats to escape and pollinate the female at which point the gnat cannot escape.

Growing conditions:

Arisaema need well drained soil. This is especially important for deciduous ones during autumn, winter and early spring. When the foliage has withered do not water apart from not allowing them to dry out completely. Perlite I find, over winter, really dries out the compost so I just spray those in pots. I will be moving my potted Arisaema over to the mix below.

Arisaema can and can do cope with monsoon type conditions during summer months.

used various combinations of compost, perlite, grite and sharp sand I have decided to use 50% silver sand and 50% humax compost for my young and older Arisaema. For seed I am now using 75% silver sand and 25% spent compost or humax compost. Arisaema seed do not like/need too many nutrients. I need to do more research on this.


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