Vanilla Growing in Uganda
Scientific Name: Vanilla planifolia
Family: Orchidaceae
Whilst working in Uganda for the Uganda Development
Corporation, one of my tasks was to develop a 24-hectare block of
Vanilla. This is a semi-terrestrial orchid, Vanilla fragrans syn. V. planifolia,
a member of the ORCHIDACEAE family. The sticks of vanilla you buy in
the shop are the pods, which have to be cured after harvesting.
The
object of developing the block was to get experience in growing vanilla
on a large scale, and eventually to provide planting material for local
African growers as another source of export income besides Robusta
coffee. Hopefully, the plantation has survived the political upheavals
of the past 20 years.
Management of the plantation involved a
three-year rotation, i.e. crop for two years and rest for one, thus the
area was split up into three eight-hectare sections.
Top Shade
Vanilla requires top shade. This was provided by Maesopsis eminii (RHAMNACEAE
family) trees, known locally as "Musizi". These are tall, fast-growing
African trees with straight lobes and a spreading canopy of small
leaves which cast a light dappled shade, ideal for vanilla. These were
raised in soil blocks and planted out 6m apart each way. They grew more
than a metre in six months. The correct amount of shade is important.
We found Vanilla is susceptible to too much shade, which tends to
weaken the vines.
Support Trees
To support the vanilla vines, we grew Jatropha curcas
(EUPHORBIACEAE) or Physic nut trees. The Vanilla roots attach
themselves to the rough bark of these trees and draw nourishment from
the organic matter and moisture in the bark. A vine in the fruit
section of the Cairns Flecker Botanic Gardens can be seen with its
roots attached to a palm tree. The Physic nut is a low-growing tree and
easy to keep in check by slashing unwanted growth to regulate the
shade. Thus the Vanilla vines had permanent living supports instead of
white ant-susceptible posts, each tree supporting two vines, one on
either side but not looped over into adjacent trees. These support
trees were planted at 3m x 1m spacings.
We did also consider
trying Casuarina as support trees without top shade, but the growth of
the species we had was extremely vigorous in that climate and we feared
that the trees might produce too much shade and become difficult to
manage in time. The "Musizi" and Physic nut combination proved easy to
manage.
Planting
Six-node cuttings are taken of mature
vegetative wood - not from wood which has flowered. Two cuttings, one
on either side, are planted up against the support trees with the
bottom two nodes under the mulch - not in the soil, otherwise they tend
to rot. If necessary, they can be tied with string to the support
trees. Use a string which will rot, not plastic twine.
In the
part of the country where we grew Vanilla and Cocoa, known as the
'fertile crescent' around the top end of Lake Victoria (Lake Amin) it
rained just about every week. But under our conditions with our long
dry periods, we would need overhead sprinkler irrigation. After
planting, there is about a three-year immaturity period.
Slashing and Mulching
Only
slashing of the grass was carried out between the rows and the trash
piled up against the bases of the vines. Vanilla roots, after having
descended the support trees then travel along the surface of the ground
beneath the mulch and across the rows under the mat of grass. Where
trash was lacking we trucked in bagasse from local sugar mills.
In
Uganda, cheap hand labour did the slashing and mulching, but under our
conditions lightweight slashing equipment would be needed so as not to
damage surface roots. Something like a four-wheel bike with wide
flotation tyres pulling a separately powered or P.T.0.-powered
twin-bladed slasher to throw the trash under the rows in one pass.
Mulching must be thick enough to, hopefully, control all weeds - so
forget Roundup®!
Pruning
Shoots from the cutting eventually
grow up through the support trees and become pendulous. Flowers form
later from the axils of most leaves. The soft tips were removed near
ground level. These were taken to the nursery and rooted under shade in
bags filled with fern fibre to supply the out-growers.
After the
beans were harvested, the stem which has borne the pods is cut back to
a growth bud near the support tree and where there are plenty of aerial
roots.
Vines were always pruned and pollinated according to
their vigour. No weaklings were allowed to bear fruit. Only vigorous,
healthy vines were brought into bearing, leaving only the amount of
mature fruit wood that the vine is able to support. When pruning, one
must always think one year to 18 months ahead, at least under Uganda
conditions. That is for the growth to form, flower set and mature its
pods.
Pollination
In Uganda, flowering occurred in March-June
and September-October. There were no suitable pollinating insects or
birds so this job was done by hand, one being employed almost full-time
and with excellent results. Using a pointed stick, he transferred the
pollen masses onto the surface of the stigma in each flower. 5-10
flowers per raceme are pollinated according to the vigour of the vine.
After pollination, the pods took about six months to form.
Curing
The
pods are ready for picking when the ends become slightly yellow. After
picking, the pods were dipped in hot water at 65 °C for two minutes.
After draining, the pods were laid in lines on a cotton (not wool)
blanket. We experimented and found a cotton blanket was best. The
blanket is then folded over the pods and then rolled up. The rolls of
blankets were placed on shelves in a dry, airy shed to allow the pods
to sweat. The blankets were unrolled each day to expose the pods to the
sun for a period of around half an hour. This was repeated until curing
was finished. The whole idea is to retain the juices in the pods and
not to desiccate them. Once cured, crystals of vanillin form on the
outside of the pods which give off a pleasant vanilla odour.
After storage for a couple of months, the cured pods were packed in tin boxes lined with silver paper and sealed for export.
Fig. 1 
Pests and Diseases
Nothing significant in Uganda. Minor problems such as snails were controlled with baits and ants with insecticide.
Economics
I
can't remember the yield per hectare or the price we received in those
days, but it was certainly profitable under our conditions with our
cheap labour! According to H. F. Macmillan's Tropical Planting and
Gardening 1991 edition, demand for Vanilla rose 10-15 years ago, the
price rising from US$15 per kg to $120 per kg. The book quotes Vanilla
as being one of the world's most profitable Agricultural Commodities.
About
18 months ago, I noticed that Vanilla was quoted at $48 per kg under
market prices in the press. Macmillan's quotes yields of from 500-800
kg cured pods per hectare per year over a crop life of about seven
years.
Taking the lower figure of 500 kg per hectare, and say $50 per kg, we have a gross figure of $25,000 per hectare. Not bad!
Using
current technology, we should be able to improve both the yield and
quality. Under our weather conditions, as well as irrigation,
windbreaks would also be necessary. Based on my practical experience, I
do not think it is sufficient just to plant vanilla in the rainforest
and let it look after itself because of excessive shade. Too much shade
I found was very detrimental to Vanilla.
Anyway, if you want to have a go at growing Vanilla, I wish you the best of luck.
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