Re: [IGSROBIN] Michael Vassar's reply to our questions
Received the responses from Michael Vassar last week regarding everyone's
questions from October, and have copied his answers in this one e-mail.
In a message, firstname.lastname@example.org writes:
<< Quesdtion: ...how do I car for Pelargonium transvaalense?
Answer: This species comes from higher elevations in the northern Transvaal
(now Gauteng) Province, where the temperature is cool and relatively humid and
winters are frost-free. In cultivation this species does best with relatively
cool temperatures in the spring and summer growing season (60-75 degrees) and
bright filtered sunlight. Winter temperatures can get down into the mid 30's
range but plants do not survive freezing weather. Growth is unusual for a
pelargonium, rather like a rex begonia, with stout rhizomes creeping along the
soil surface. Plants are easily propagated by removing rooted side shoots from
the larger rhizomes. Plants should be fertilized in spring and summer with 1/4
strength fertilizer such as 20-20-20, 15-30-15, etc., every 2-3 weeks.
Question: how do I get Pelargonium anethifolium to flower. How do I care for
Answer: Pelargonium anethifolium is a winter growing species from the Western
Cape. It forms large tuberous roots and plants can grow quite large. Plants
should abe grown in a well-drained mixture of sand, gravel and a small amount
of decomposed organic material. The key to getting plants to bloom well is to
grow them in large containers (10 inch/25cm or larger) and agrow them in full
sunlight. Plants grown in low light will not bloom. [This species is virtually
a form of P. triste with finely divided leaves.]
Pelargonium reniforme is a summer growing species from the higher elevations
of the Eastern Cape. Plants grow vigorously from spring to autumn then go
dormant in late autumn but usually do not loose their leaves if they are still
getting some water. I find they survive winter dormancy better if the soil is
not allowed to dry completely and, of course, the pots should be kept above
freezing. This species does best when grown in full sunlight in a planting mix
that is well-drained but with more organic matter than for P. anethifolium.
Many forms are in cultivation from small plants with tufted growth to rather
vine-like forms and even the variety velutinum with 4-inch diameter leaves
that are acovered with silvery hairs. I use a 15-30-15 liquid fertilizer at
1/4 strength every 3-4 weeks for lots of flowers.
About Geranium tubverosum and G. malviflorum - I don't know! Robin Parer
could answer these correctly.
Question: how do I care for Pelargonium xerophyton?
Answer: Pelargonium xerophyton is one of the nicest of the dwarf succulent
species. This is a winter growing species from northern parts of the Western
Cape. Plants should go completely dormant in summer and begin to grow again in
mid-autumn. Plants require a rapidly draining planting mixture of mostly sand
and small gravel with little or no organic matter. Full sunlihght is required
for best growth and to keep the plants dense and tight like they are in
habitat. Keep this one in a relatively small pot, only moving up to a larger
pot (in autumn as plants come out of dormancy) when the pots are full of
roots. Water only when the surface of the planting mixture begins to dry. This
species blooms from late winter to early summer when plants go dormant. Large
mature plants will have hundreds of flowers. The first cutting of P.
xerophyton HBG40665 which I received about 20 years ago took more than two
years to root and begin to grow and produce its first leaf! I almost thre it
out - sure glad I didn't!
I don't know what to say about Pelargonium 'Renate Parsley' as I have never
seen nor heard of this cultivar. Need a description or photo.
Question: How do I propagate tuberous pelargoniums vegetatively?
Answer: These species are very easily propagated from tuber cuttings or
divisions. Winter growing tuberous species should be propagated (stem or
roots) just as they begin to come out of dormancy in autumn (usually about
mid-September to mid-October here is Southern California). Summer growing
tuberous species should be propagated when plants begin to come into active
growth in spring after the coldest weather has passed.
Plants with large tubers, such as P. triste, can have the tubers cut or
snapped into 2-3 inch sections and each piece used as a cutting. I prefer to
remove the smaller tubers that attach to the large tyubers as there is less
chance of rotting from smaller wounds. Plants with rounder tuberous roots such
a P. rapaceum can have the many small tubers removed that come off the large
main tuber. I have gotten as many as 35 plants from tubers off one P. rapaceum
plant in a 4-inch pot. One most important thing to remember - tubers and
pieces of tubers must be planted in the same orientation they were on the
plant - up must be up and down must be down or the tuber cuttings just s sit
and do nothering or rot eventually.
Plants grown from tuber divisions and cuttings will flower at the normal
blooming time for that species. For examplle, small plants from root divisions
of P. triste should be well-rooted and with 3-4 leaves in about 3 months. Move
plants to a larger pot at that time. They will then flower in spring (assuming
they get enough light). Plants grown from tuber divisions/cuttings grow and
flower faster than seed grown plants.
Tuber cuttings should be planted in the above mix and should be set so the
upper 1/4 inch of tuber is above the planting mix surface. I find that light
helps induce adventitous buds.
Question: Culture of Geranium tuberosum (Marisa)?
Answer: Again, Robin could give a better answer to this. But from what I'm
reading into the information given, it seems that her conditions are not what
G. tuberosum likes. I don't know where she lives, but suspect that this
species needs more winter chilling than it is getting. Another possibility is
that this species is just simply short-lived and reseeds readily each year
where it does well. If it won't grow and do well, there are many other
species/cultivars that will readily take its place!
P.S. The delay in receiving messages sent through the IGS Robin seems to have