Recommended Zone
- To: perennials@mallorn.com
- Subject: Recommended Zone
- From: j*@accessus.net (Amber Hearn)
- Date: Thu, 8 Jan 1998 12:03:32 -0600
>Date: Sat, 27 Dec 1997 03:20:02 -0800
>From: "Merlene A. Teresky" <niteowl@netdex.com>
>Subject: Recommended Zone
>
>Hi Perennial Lovers;
>
>Can anyone help me with regards to understanding how to read recommended
>plant zones. For example, if a plant simply states zone 4 does not
>mean it can only be grown in zone 4 or does zone 1 - 4 stand the best
>chance of success. Or, is zone 4 - 14 the way to read this. I hope I
>am not the only one with this feeling of frustration and confusion.
>Does anyone know of a website for this type of information? I would
>sure appreciate any information regarding this question.
Hi Merlene,
You will find zone listings written usually one or two ways.
One example is USDA Z4-8: What this means is that the plant is cold hardy to
Zone 4, Where the maximum cold temperatures it will receive are around -30F,
-34C, and it will thrive up to zone 8, but will not do well where there
isn't enough winter cold to induce blooming or there is too much heat and
humidity. Most good texts will give you some indication of both, but many
are very conservative.
Another example is USDA Z5: When only one zone is listed it is the coldest
zone the plant is hardy to. This plant would probably not take the cold
temperatures in Zone 4. This is the way most catalog writers do it simply
because there is not good reliable information available on how good the
plants will do in the warmer climates, and they don't have any personal
experience in warm zones.
USDA Zone information is based on average maximum cold temperatures in a
given area over a period of time. Each zone is given a rating. For example a
plant that is said to be hardy to Zone 5 can be assumed, in general, to be
hardy in most areas where the temperatures do not get below the range -10 to
-20F (-23 to -29C). Below is a little table to tell you what each one means:
____________________________________________________________________________
USDA Zone Max Cold Fahrenheit Max Cold Celsius (Centigrade)
1 Below -50F Below -45C
2 -40F to -50F -40C to -45C
3 -30F to -40F -34C to -40C
4 -20F to -30F -29C to -34C
5 -10F to -20F -23C to -29C
6 0F to -10F -17C to -23C
7 10F to 0F -12C to -17C
8 20F to 10F -7C to -12C
9 30F to 20F -1C to -7C
10 40F to 30F 5C to -1C
11 above 40F above 5C
__________________________________________________________________________
You should always keep in mind that these are just general guidelines put
out by the US. government and are used as such by most gardeners who have
been gardening for very long. I live in Zone 5, but I grow many plants here
that the catalogs and reference books list as not being hardy here. I also
find that there are some plants that should be hardy here that I cannot grow.
Hardiness is based on more than just how much cold a plant can handle. In
reality, there are people in areas where the temperatures may fall into the
-30 range that can grow zone 7 or 8 plants because they dependably have snow
cover the whole time it is cold, which keeps the plants at just around
freezing temperatures. They never feel the cold. There are other factors
involved as well, such as the heat of summer, humidity, precipitation and
altitude. Most important is the microclimate of your garden. Mine is open
and windswept on what used to be prairie. I have more trouble keeping some
things than does my friend who lives down the road, but in town, surrounded
by buildings which absorb heat during the day and reflect in back during the
evening, keeping things warmer and blocking the freezing winds. His
hardiness zone in his garden right here in Zone 5 is more like the cold part
of Zone 7. Mine is more like the cold part of Zone 4.
As a gardener you can affect hardiness within your own garden. Siting is
important. If a plant may not be hardy give it a warm site with a south wall
or large evergreen to the north of it. Or try planting it where it is dryer
in the winter, or back it with a large dark colored stone that will absorb
the winter sunlight and warmth. Adding a winter covering of mulch will
increase the hardiness of a plant by at least one zone if it can handle
being covered in the winter. Some plants I couldn't otherwise keep are
perfectly cold hardy, but cannot stand all the wet we have in winter so I
actually cover them with plastic roofs to keep them dry. Others cannot stand
winter sunlight and must be covered or they will scorch.
The high end temperatures would probably be harder to fool as you simply
cannot find a way to make peonies bloom in Zone 10 unless you put them in
the freezer for three months.
Crazy and complicated you might think, and in a way it is. It certainly is
no exact science. However, the best advice I can give is to experiment. Do
try plants that are not rated as cold hardy for your area. Try different
things with them. Be creative. If you want to grow a plant badly enough you
can find a way. I follow the advice of Tony Avent, owner of Plant Delights
Nursery whose motto is "I consider a plant hardy until I've killed it
myself, three times." If I want to grow the plant I ignore the zones and
give it a try. You just never know for sure until you put it in your own garden.
Good luck
Amber Hearn
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Amber & Wayman Hearn jadare@accessus.net
Whippoorwill Creek Nursery USDA Z-5
943 Foxville Road mintemp = -15F/maxtemp = 102F
Kell, IL 62853
618-822-6000
Whippoorwill online - http://www.wcn.simplenet.com/Welcome/welcome.htm
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