Growing information

We do our best to provide useful information on selecting and caring for plants. Our database includes the water requirements, light requirements, hardiness zones, flowering times, and propagation methods for each plant. We also provide estimates of how large each plant can become in the landscape.

We rely on our own gardening experience and a variety of reference materials, including books, seed catalogs, and websites. Please tell us if you notice any mistakes, and let us know if you can provide information that might help our visitors.


Water requirements

Low moisture— Generally dry soil without irrigation. Watering is only necessary for new plantings or during periods of extreme drought.
Moderate moisture— Generally moist soil without prolonged wet or dry periods. Regular or occasional watering may be required to maintain these conditions.
High moisture— Constantly moist or wet soil. Substantial irrigation may be required to maintain these conditions.

Light requirements

Shade— No direct sun during any part of the day.
Partial shade— Filtered sunlight or direct sun for just part of the day.
Full sun— Direct sunlight for all or most of the day.


Hardiness zones

Hardiness zones are geographic areas defined by their average low temperatures on the coldest day of the year. The 11 USDA hardiness zones are listed below, along with the corresponding average low temperatures.

Zone 1
Below -50° F
Below -45.6° C
Zone 2
-50° to -40° F
-45.6° to -40° C
Zone 3
-40° to -30° F
-40° to -34.5° C
Zone 4
-30° to -20° F
-34.5° to -28.9° C
Zone 5
-20° to -10° F
-28.9° to -23.3° C
Zone 6
-10° to 0° F
-23.3° to -17.8° C
Zone 7
0° to 10° F
-17.8° to -12.3° C
Zone 8
10° to 20° F
-12.3° to -6.6° C
Zone 9
20° to 30° F
-6.6° to -1.1° C
Zone 10
30° to 40° F
-1.1° to 4.4° C
Zone 11
Above 40° F
Above 4.4° C

We use hardiness zones developed for the United States by the U.S. Department of Agriculture. Some other countries have adopted different numbering systems. Please see the Wikipedia article on hardiness zones for a comparison of the different systems and links to hardiness zone maps.

Perennial and woody plants are commonly given hardiness zone ratings to indicate their ability to persist from one year to the next. We also include appropriate hardiness zones for the annual plants in Plantwire, simply to suggest the regions that might have a suitable growing season.