After growing Kava for the best part of 20 years (and out of its natural climatic range), I’ve settled on a few things that are needed to successfully grow Kava in the subtropics. The post will hopefully help those trying to grow kava, whether in the tropics, subtropics or even the temperate areas of Australia.
Kava is a perennial tropical shrub native to/cultivated in the SouthPacific Islands, including Vanuatu, Fiji, Samoa, Tonga and Tahiti. Kava prefers lower elevations, consistent moisture and partial sun. It is often grown under the shade of another crop like young coconut palms or papayas. Artificial shade is also used in PNG for example (thatched cover of coconut palm fronds).
Early efforts of growing Kava west of Brisbane were good, but winter generally was a touch too cold to keep them thriving. They were fine if the watering was reduced in the lead up to the colder months and the plants were brought inside a hothouse. Other people mulched the base of the plant heavily over winter and left them outdoors. The mulch protected the crown of the plant and the Kava would shoot very well when things warmed up again.
Generally the main factor letting down the successful cultivation of Kava IMO was the soil medium. I tried a lot of different mixes and eventually came to the conclusion that the mix we used was just too heavy. The roots couldn’t get enough oxygen and damping off of the roots was the main problem. Kava has roots that can be damaged easily and if the medium is too heavy, root rot will be the ultimate cause of death.
I remember reading that a traditional way of growing Kava was to plant a cutting or small plant in the dead stem of a tree fern. This would give the plant nice long roots that attracted a premium price when sold. Thinking about this method I started using an orchid mix I developed specifically. This is a mix of coco chip (50%), large sized perlite (25%), pumice (15%) and fine coco peat (10%). The change in the plants has been dramatic. Root growth is phenomenal and the plants need to be potted up regularly to accomodate the root growth. The benefit of this medium is that the roots have plenty of room to move and they really attach to the larger particles well providing stability.
Watering Kava in an orchid mix is hard to overdo. Not saying you cant do it, but it’s harder to kill them with water. As most people probably tend to over water rather than underwater, the orchid mix is better at regulating this.
Kava is a fairly hungry crop and it can be fertilised every 1-2 months in most areas during the warmer growing season. Don’t fertilise over winter/dormancy. Osmocote or organic products work well; I haven’t come across anything they don’t like in moderation.
The main pests of Kava are scale insects, mealy bugs and aphids. Also susceptible to a number of viral diseases, such as CMV (cucumber mosaic virus). I don’t use oil products on Kava plants, but it is fine to use Natrasoap, pyrethrum etc. Often the problem is not the mealy bugs or aphids on the plants but the ants that are spreading and farming the pests. Control the ants firstly and then control the pests.
Note: Currently (2019) Kava is scheduled in the Northern Territory so you’re best not growing it up there.