Dear PBS forum,
Gordon has very kindly replied to the inquiry of Rob Hamilton. He
suggested for a better understanding of his philosophy firstly to post the
integral text of his talk of at the IBSA conference. Mary Sue mentioned
already several points. But you will see that his experience is of great
value and corresponds very well wih the actual topic of the week.
Regards Lauw de Jager
CREATING THE RIGHT ENVIRONMENT AND CONDITIONS
It is never my intention to tell people how to grow our winter rainfall
bulbs and corms, but rather to share my experiences of growing them over the
past 15 years or so.
The Illustrated Oxford dictionary defines;
ENVIRONMENT: as - surroundings, region, conditions or influences
and CONDITIONS: as circumstances, especially those essential to a ëthingsí
existence.
With this in mind, I have adopted, over the last couple of years, a very
simple common-sense approach to growing bulbs and corms.
It is always good to listen and learn from other successful growers,
however at the end of the day it will be very much a trial and error
experience. One is never too old to learn.
My main interests are the winter rainfall geophytes of the Western Cape,
Northern Cape, Namaqualand and to a lesser degree the Southern & Eastern
Cape.
Until recent times little was written, documented and published on the
active cultivation of our indigenous geophytes. Fortunately the
Kirstenbosch Gardening series by Graham Duncan and the very recent "Color
encyclopedia of Cape Bulbs" by Manning, Goldblatt and Snijman have served to
remove much of the previous "myth" that these bulbs and corms were
difficult, if not impossible to grow.
There are certain genera and species that do prove difficult to grow such as
Gladiolus bullatus, G. cardinalis and G. nerinoides, however by creating the
right environment and conditions (similar to their natural habitat) it is
possible to cultivate them and others, successfully. In the 'Color
encyclopedia of Cape Bulbs' the authors state "Most bulbs (and Cape Bulbs
are no exception) respond best in cultivation if their natural growth
requirements are duplicated as closely as possible"
Provided one uses a sound nutritious, (probably neutral) well-drained soil
medium, the three next most important denominators for successful
cultivation are;
Aspect (ie. situation)
Planting strategy
Feeding (& watering)
Before dealing with each of these issues, I am of the opinion that the
potential grower does need to know something of the environment and
conditions that the seed or bulb/corm originated from. If this information
is not automatically forthcoming donít be shy to ask! Without this
knowledge it is tantamount to ëtravelling without a road mapí! I believe it
is encumbent upon all suppliers/distributors of seed and corms to divulge
this information (or some similar advice) thereby enabling potential
growers/growers to make an educated or calculated decision as to the
appropriate growing medium, aspect and watering requirements.
ASPECT: Ideal is a south/south-east aspect, preferably benefitting from
morning sun, although full sun is not essential. The late afternoon setting
sun can prove quite harsh, particularly in late Autumn or late Spring when
temperatures on the whole are quite raised. In their natural habitat, far
more geophytes (& general Fynbos) will be found on the cooler and damper
S/SE facing aspects. Of course there are those plants which favour the
drier and warmer N/NW aspect. A point of interest, many of the Iridaceae
species will naturally flower facing S/SE.
HOUSING: Where one experiences heavy night/early morning dew, it is
advisable to grow the softer leafed species, such as Daubenya's,
Lachenalia's, Gethyllis, Massonia's as well as certain Freesia's, Romulea's
and Geissorhiza's amongst others, under cover. However, always ensuring that
there is sufficient natural light and good, free air movement. I certainly
have enjoyed far greater success since adopting this approach. it has
reduced incidences of crown rot, Botrytis and Fusarium infections to almost
nil. One does however, have to be extremely vigilant and most wary of
infestations of Mealy bug, Aphids and Red spider mite (due to the drier
conditions) and take the necessary curative action. There is also a
noticeable reduction in the incidence of rust to which certain species of
Lachenalia's, such as L. unifolia, L. variegata & L. viridiflora are
particularly prone. The need for full sun (whilst probably ideal) is not
from my experience essential or indeed necessary. Yes, one will produce
slightly lankier plant growth, but then that is also what happens in their
natural habitat when growing from under the protection of fynbos/shrubbery.
PLANTING: I always start with a good neutral, well-drained (ie. porous) soil
medium, made up of ± 60% river sand and ± 40% commercial potting soil
(containing no superphosphates!) to which I add additional nutrients/
additives through the growing season. An aspect of planting that I
overlooked, to my detriment, for many years is the depth that one plants
mature bulbs and corms. Consider the normal growth cycle from seed. The
plant pulls itself down to the optimum level before producing flowers. So
when planting mature or near-mature bulbs/corms, err on the shallow side
rather than too deep. Too deep and you will produce spindly plants that
will finally give up the ghost. On the other hand, planted too shallow,
they might require a little more time to flowering properly. Also don't be
shy to plant your bulbs/corms grouped together ie. in the middle of the
container. I am convinced there is a symbiotic influence. Certain corms
such as Lapeirousia's, Romulea's and Hesperantha's are bell-shaped with a
flat bottom, plant these at an angle to assist their movement down to the
optimum level (I always make a note of the depth of existing bulbs/corms
when re-potting).
FEEDING: An absolute no-no is the addition of any phosphates to the winter
rainfall geophytes. However, they do respond well to a regular feeding
(once per month) of Magnesium Sulphate (good leaf structure), Potassium
Sulphate (Bulb & Flowering development) & Ammonium Sulphate (for Nitrogen
and lowering of the pH of soil). Agricultural limestone can be added for
those requiring a raised pH above neutral such as summer rainfall species,
Nerine's, Cyrtanthus etc. Associated with feeding is of course watering,
provided one adopts a good growing medium ie. that drains well, you can
never never over-water your bulbs and corms. Also another never never is to
allow your container to dry out! How would you react to being deprived of
water! Again a common sense approach. Where one experiences incidences of
crown rot, provide water from below.
Finally temperature does have its part to play. Generally bulbs/corms are
tolerant of extremes in temperature. There are certain of our ëAlpineí
types, such as Gladiolus cardinalis & G. nerineoides (to name but two), for
them to flower successfully one needs to provide a cool S/SE aspect, for
they flower in the Western Cape's warmer months, but at high altitude and
thus much cooler.
Many myths and indeed untruths have been created and espoused around the
difficulty of cultivating S.A. indigenous Bulbs/Corms which has
unfortunately had a profoundly negative effect of creating an ethos of
"conservation through cultivation". Only in recent times has a reasonable
amount of good seed and bulbs/corms become available to the enthusiast and
this is largely due to IBSA and its members (some of whom are commercial
suppliers and growers).
However if we are to succeed even further, personal agendas need to be set
aside, with successful growers willingly and genuinely sharing all their
knowledge and expertise, thus ensuring that we practise what we preach and
prove ourselves to be GENUINE CONSERVATIONISTS.
CREATING THE RIGHT ENVIRONMENT AND CONDITIONS
University of Stellenbosch
Gordon Summerfield
Lauw de Jager
Bulb'Argence