Re: Psoralea pinnata

david feix wrote:

I would have to disagree with Moira's concerns about
Psoralea pinnata being a water hog at the expense of
other plants.  At least, this has never been a problem
in gardens where I have used this species.  In our
heavy clay soils, it is actually moderately drought
tolerant, and although it certainly grows faster and
lusher with regular water, it also does fine with once
 every 10 day watering in height of summer for me.  I
have not noticed any undue root competition with other
plants planted at its base, and in my own garden which
is thickly planted with little clear soil, reseeding
is minimal.  It is tender to heavy frost, and died
completely in the 1990 and 1998 freezes here at 25F
temps.  I find it is good for 8~10 years as a garden
plant if the blooming tips are cut back after
blooming, and the plant is light tip pinched on a
periodic basis to keep it looking fresh.  It does  not
resprout well from hard wood, and is probably best
treated as an overstory small multi trunked tree in a
shrub border.  It has gotten 15 feet tall for me when
allowed to, and will also still bloom well in dappled
shade.

It was interesting to see this plant in habitat in
Cape Town, where it is all over Table Mountain.  It
was of course the best looking where it was in
drainage courses, but could also be seen growing in
much drier situations.  Under drought stress both here
in California and South Africa, it responds by losing
lowest branches and only retaining growth at the top
of the plant.  As such, it requires regular pruning to
keep it looking clean, as it quickly builds up lots of
dead branches if not well watered.

There is also considerable variation in both length of
flowering season and amount of floral fragrance.  The
form offered by San Marcos Growers has an earlier and
longer bloom season than a form I had gotten from
Strybing.  I supplied seed of this Santa Barbara clone
to Annie's Annuals Nursery, which she is now growing
in 4 inch size.  This clone will often start blooming
as early as March with repeat bloom into June/July, as
compared to the non-fragrant clone from Strybing that
only bloomed in May/June for me.
David
Our differing experiences with this plant obviously relate to quite different soil types. The only 2 specimens of Psoralea I am familiar with are both growing in very sandy soils, in each case only a few hundred yards from the beach. Under these conditions I can assure you plants within their root zone can become very dry and unhappy over summer.

I can also vouch for the loss of the bottom branches in both cases, leaving a small tree shaped like an umbrella.

Moira
--
Tony & Moira Ryan,
Wainuiomata, North Island, NZ. Pictures of our garden at:-
http://mywebpages.comcast.net/cherie1/Garden/TonyandMoira/index.htm
NEW PICTURES AND DIAGRAMS ADDED 20/Feb/2005

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