Help with out of zone plants

waynebo

8 years ago

I would like to grow a yellow twig dogwood here in Ca. SF bay area zone 9.

it is usually recommended only up to zone 7. Does anyone have any experience with lower zone plants in warmer climates?

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gardengal48 (PNW Z8/9)

8 years ago

The USDA hardiness zones apply ONLY to winter cold tolerance!! They have absolutely nothing to do with suitability to a warmer than listed zone and providing that "range" only confuses the issue........as your comment indicates :-))

Theoretically, any plant that is listed for a zone lower than yours can be suitable - they will certainy withstand any winter cold - but there may be circumstances that would limit that, as in abnormally high summer temps, excess humidity, or lack of summer heat to sufficiently ripen wood.

Regardless, any of the common shrub dogwoods that have colored stems - Cornus alba, C. sericea or C. stolonifera - will be fine in zone 9. Cornus sericea is actually native to much of your area, as it is to pretty much all of the coastal portion of the western US. And while these can be moderately drought tolerant when well establshed, they will perform better if in moist soils.

Rather than considering just the USDA hardiness zones for plant suitability, I'd suggest investing in a copy of the Sunset Western Garden Book. This is pretty much the gardening 'bible' for anyone on the west coast as it has its own set of hardiness zones that take into consideration a much broader range of conditions, including annual rainfall, geography, summer heat and humidity, length of growing season, prevailing winds, etc. These reflect the very wide range of gardening situations present here that are completely overlooked by just a winter cold tolerance rating.

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Comments (6)

pip313
8 years ago
If a supplier lists a max zone at least research it with your particular plant.

there are cases where you wouldn’t want cold zone plants in warm zones. But the only ones I can think of are fruiting plants needing the frost hours.
waynebo thanked pip313
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waynebo
Original Author
8 years ago
I was thinking along those lines. My thought was that it possibly needed the cold of winter to make its yellow branches more vibrant - same with the red twig variety. I searched online and even called the nurseries that sold them. I was still unable to find any reason a plant rated for lower zones wouldn't do well in a higher zone.

Thanks for your reply
waynebo
Original Author
8 years ago
To Gardengal - Yes - confused on why there would be a max zone unless it was for flowering or fruiting purposes. Also I agree on the Sunset book. Every gardener is this area knows very well of the microclimates that exist here and that guide is extremely helpful when planning a garden.
gardengal48 (PNW Z8/9)
8 years ago
waynebo - please notice my zone :-) I live in a very mild winter area as well but likely a bit colder than yours (water influence in my case). Red twig dogwoods, Cornus sericea, are native here and very obvious in the winter when out of leaf and the red twigs are most noticeable. But most of western WA is at least a zone 8, so that vendor's plant tag is completely off.

As a professional horticulturist, I ignore any upper range with any plant hardiness listing as they seldom have any logical application. There are of course other factors that wll affect how well a plant will do in a specific climate or location but not ones that have any association with winter cold tolerance. Which is ALL the USDA zone system was intended to predict!!

As mentioned previously, doing a bit of research will confirm suitability so you do not need to rely on the artificial concept of that silly zonal range :-) And the Sunset book is a great place to start. And I find it to be on the conservative side of the issue as well.
waynebo
Original Author
8 years ago
Agreed

I must have 3 or 4 "zones" in my own yard. Probably more of a CYA legal designation than practical application. Besides, experimentation is the greatest part of the horticultural journey.

Cheers