I received an email from a collector named Jim Rumrill in New Jersey. For those of you that live in that zone, read ahead and find out how Jim grows his Amorphophallus successfully. Thanks Jim!!

Snow,

Amorphophallus in a Northern Temperate Zone Climate As a fellow amateur tropical plant grower who lives in northern New Jersey saddled with an unfriendly winter season, I hopefully have a few helpful suggestions for those similarly situated. Thus far 55 Amorphophallus species plus 9 yet to be identified are being greenhouse-propagated in pots. Having learned the hard way (trial and error) over many years, the following suggestions are offered for those whose trials end up with too many errors.

Dormancy: Unlike a few such as A. coaetaneus and A. verticillatus that may have little or no down time, most do. A few may be capable of extended dormancy such as A. haematospadix, which sometimes exceeds two years. When a plant goes dormant, it’s immediately repotted in new nearly dry mix, than stored in a cellar that stays around 60 degrees. No tuber is ever left exposed to air, thus desiccation is rarely a concern. The only exceptions to the dry treatment are those that are known to need some moisture while dormant such as A. croatii and A. tonkinensis.

Pot Size: Unlike most Amorphophallus growers, I’m an advocate of under-potting for this and most plant genera. Amorphophallus has a fairly weak root system in comparison to leaf and tuber size and tend not to suck up moisture very fast. Therefore over-potting in plastic pots can lead to overly wet conditions that can lead to anaerobic conditions, which in turn leads to root rot and finally to the gnashing of teeth. Clay pots will permit more leeway in pot size because of moisture and air permeability.

A. hewittii and A. gigas are just two examples of species that are especially intolerant of being over-potted. As an example my hewittii seedling with a 37” petiole and 41” across the leaf is in a 5” pot. It looks silly and won’t stand upright without help, but is happier than a pig in (you know what.) It’s not unusual for a bulb to split a pot open. A deformed tuber beats a rotted one any day.

Potting Soil: As far as commercial potting soils go, there is none better than Fafard 52 Mix. (I have only been able to obtain this from a wholesaler here in NJ.) It’s also great for Alocasia, Colocasia and their relatives that go downhill fast in our New Jersey short-day low-light winters. I should warn that it contains bark so a low nitrogen fertilizer should probably not be one’s first choice.

Fertilizer: Here again I know I’m swimming against the tide, but I also happen to be an advocate of under-fertilizing. I’m sure most are aware that rats in the lab when placed on a starvation diet tend to live longer than those well fed. The same can also apply to plants if longevity is the aim at the expense of pushing plant size and flowering. Frankly I enjoy the several months of foliage more than the few days that the flower lasts. Just keep in mind that as lush as tropical vegetation may look in nature, the soil is often unexpectedly nutrient poor. That’s why slash and burn farmers must move on so often.

Most tropical plants have evolved a means to get by with rather meager nourishment. In any event, need you be warned of the danger of over-fertilization? I personally like a well-balanced one such as 20-20-20 with micronutrients, but never at full strength.

Watering: Extremes should be avoided. Amorphophallus growers are generally too advanced for the need to be warned about the evils of pot over-watering. Reserve that procedure for your Anubias and Cryptocoryne! But going to the other extreme and leaving a plant get too dry in between watering can lead to premature dormancy, hardly lethal, but certainly undesirable!

Outside Summering: Don’t do it unless a greenhouse is lacking. Drenching rain, hail, wind, pot-digging chipmunks, over rambunctious squirrels, foraging deer and ravenous insects are just a few of the problems that can break one’s heart. If pot culture indoors is not an option, at least stake the petiole for protection from the wind. Some kind of overhead plastic protection from excessive rain is another thing worth considering.

Cheers,

Jim Rumrill

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