Amorphophallus Grow Guide

Amorphophallus overall are very vigorous robust plants that are heavy feeding, always. Generally only the rare species are particularly slow growing but this can be resolved with a bit of extra care, specifically fertilizing. Some of the species are cold hardy but all of them grow quite well in warm intermediate conditions. In fact, many of the species can grow nearly nonstop if given lots of fertilizer and warmth year round, without entering dormancy for extended periods. However, for ease of growing it is often better for there to be a dry cooler period in winter to induce dormancy - this makes repotting and dividing much easier along with giving a reprieve from growing.

Growing conditions are quite relaxed, intermediate warm with bright lighting works. When in active growth, the plants are very heavy feeding - otherwise they will go a bit yellowish at the tips from potassium deficiency. A high ratio Potassium fertilizer with a bit of ammonium is a must. Some growers use nutricote types heavily which can be convenient but typically I recommend regular type fertilizers that are dissolved at watering. On an EC meter you are aiming for 1.2 EC. Since the conversion varies per brand, it is hard to say but this comes out to around 800 ppm on a TDS meter. This rate is given every watering with a bit of dolomite lime used on the soil surface every couple months to supply Magnesium and balance the PH. It works incredibly well on Amorphophallus and is especially important when using rockwool cubes - which produces much faster growing Amorph than peat blends.

For the rare species like A. pendulus there is typically a micronutrient deficiency that eventually triggers a corm rot. This can be resolved by supplementing but many fertilizers are created for vegetables, not tropicals. We do supply an orchid fertilizer that has the additional micronutrients like higher Boron - it works very well on the Amorph. 

Pest issues are uncommon typically but it is not uncommon to hear about issues with nematodes. What happens is little pitted rotted areas of the corm that eventually rot out the entire corm if left untreated. Unfortunately, it is not a simple matter of "use this" since the majority of effective nematicides are restricted use. All the more reason to buy from sources that are definitely free from this nasty pest. All of our tubers are nematode free for instance. However, there are various guides on cleaning the wounds etc, but my advice is simple, soak the tuber in an avid/abamectin drench for an hour or so. It is not commonly known but this common miticide does stun many nematodes and is even used in commercial applications for this pest. 

During dormancy most species actually prefer to be kept mildly moist. It is common practice to store them bone dry to "prevent rot" but this causes a lot of issues, especially desiccation for the smaller species. It also delays new growth. If the tubers are healthy then they typically have no issue being stored a tad moist, whether in Sphagnum, rockwool, etc. This is strongly recommended for species like A. ongsakulii.