Zantedeschia hardiness

FYI, we are growing two wild collected forms (2005) in addition to the
many named cultivars of Z. aethiopica. Both have fared well through out
2008/9 winter, which hit 7-9 degrees F in this section of the garden.
One is from Eastern Cape Province: Stutterheim; 3330' elevation and the
other is from the West. Cape Prov.: Swartsberg Pass 4346' elevation.
Both are growing very well, but the Western Cape plant is much taller
and more robust. I will put these on the list to divide in the future
and it will be interesting to see how they fare where other clones have
failed.

Tony Avent

Plant Delights Nursery @
Juniper Level Botanic Garden
9241 Sauls Road
Raleigh, North Carolina 27603 USA
Minimum Winter Temps 0-5 F
Maximum Summer Temps 95-105F
USDA Hardiness Zone 7b
email tony@plantdelights.com
website http://www.plantdelights.com/
phone 919 772-4794
fax 919 772-4752
"I consider every plant hardy until I have killed it myself...at least three times" - Avent

John Grimshaw wrote:

Jim McKenney wrote:

I've had problems with Z. aethiopica too, but I think the root of that is
that this species is a winter grower which only very reluctantly changes
seasons.

This issue has been touched on but I think not yet fully explored.
Zantedeschia aethiopica has a wide range in South Africa, encompassing both
winter and summer rainfall areas.

It seems sensible to me to assume that most importations of Zantedeschia
aethiopica have been from the area around Cape Town, where it is very
common, even growing at the very tip of Cape Point. These winter growers
would certainly be tender in northern Europe, necessitating the glasshouse
culture/underwater techniques to survive.

I have collected seed of Z. aethiopica on the Sani Pass, in Kwa-Zulu-Natal,
a classic summer-rainfall location and source of many hardy plants for UK
gardens. The seedlings are absolutely hardy here and flower in midsummer.

Mulling over it, I came to the thought some time ago, that the generally
reliably hardy clones in the UK, e.g. the old but unspecial 'Crowborough'
and the recently named 'Glencoe', are probably from the summer-rainfall
area, though this is impossible to prove. If so, it demonstrates the
importance of provenance when selecting South African material for garden
use. (Another plant with similarly wide distribution in SA & reputation for
tenderness is Melianthus major: again, one suspects that most seed has come
from the Western Cape, and one wonders how material from the Drakensberg
would fare.)

The pink-throated form of Z. aethiopica also seems to be entirely hardy
here, and occurs in eastern south Africa somewhere as a wild plant.

Z. albomaculata survives outside here, but is late to emerge, and does not
flower very freely.

John Grimshaw

All messages in my Inbox received between September 2008 and 30 May 2009
have been deleted: please resend anything you feel is important!

Dr. John M. Grimshaw
Sycamore Cottage
Colesbourne
Cheltenham
Gloucestershire
GL53 9NP

Tel. 01242 870567

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