GardenSMART Newsletter Signup
Visit our Sponsors!
Visit our Sponsors and win.

WHAT DOES USDA Hardiness Zone mean?

HOW TO Root Begonias

Anne K Moore, February 12, 2010
Photographs by Anne K Moore

I have received a couple of questions this week that I thought might interest you.

First QUESTION:  When one refers to a plant as hardy in Zones 5-8 what does that really mean? I am grateful for an answer. Thanks.


The USDA (United States Department of Agriculture) has adopted a map which shows the expected high and low temperatures for a given area.  The zones are divided on this map and numbered.  It is based on the coldest climate in which a plant will survive. 

If a plant is listed as hardy in zones 5-8, it means that it will withstand the cold temps up to zone 5 but will most likely freeze out in lower zones such as 2, 3, 4.  It also shows that it will withstand the heat up to zone 8 but will probably die out in a hotter climate of 9, 10, 11.  The best growing conditions for this plant would be between and including zones 5-8.

It isn't a perfect system but it does give gardeners an idea of where a plant will grow and thrive.  For instance, the canna pictured here can be left in the ground in zones 7-11 but the rhizomes need to be dug and stored indoors in the colder zones of 3-6.  It would be listed as hardy in USDA Zones 7-11.

This site shows the differing plants in the different zones:

You can find your zone here by entering your zip code:

The USDA Zone map is here:

Second QUESTION:  Can you tell me how best to get cuttings of house plant begonias to root? I have 2 lovely plants, but they have gotten long, lanky and thin.  I think I should prune them back, but I'm not sure of details.   Thank you.

ANSWER:  Begonias are some of the easiest to root from cuttings.  You can start them in a glass of water.  It is better if you don't wait until the stems are so long and thin, but it won't hurt to try.  Cut the plant back to just a few inches high and you will get new growth from the roots.  Or, you can cut it to the size you want, or a little below, and it should branch from there.

Remove all of the leaves from the cut off stems you want to root.  Also cut off the floppy tips and any flowers.  You want as strong a piece of stem as you can find.  Be sure you know which way is "UP" after you cut them.  They will not root if you put the tops down in the water.

Put the trimmed stems, bottoms down, in a clear glass of water on a windowsill that gets good light, even sunlight.  I like to use a Kitchen window so that I remember to add water as it evaporates. 

At least weekly, dump out the water and add fresh.  When you add or put in new water, let the faucet spray it into the glass.  This helps to aerate the water, which the cuttings need.  Be careful not to use too much water force on the newly emerging roots.  After roots form and are at least a couple inches long, pot them into good potting soil and keep them a little wetter than usual, letting them dry slowly so they transition to the soil from the water.

All articles are copyrighted and remain the property of the author.

Article URL:

Back to Articles List                               

GardenSMART Featured Article

By Justin Hancock, Costa Farms Horticulturist, Photographs courtesy of Costa Farms

Gardening indoors and out come with their own sets of challenges and opportunities, making it easy to master one and struggle with the other. If you're one who puts your focus outdoors, but you want to enjoy the beauty and air-purification properties of houseplants, start here! Read more...

Join fellow garden lovers, history buffs and music enthusiasts to discover the quaint towns and colorful gardens of Holland and Belgium in May of 2018.

This exciting journey will be hosted by nationally known host Eric Johnson, of Public Television's blockbuster show GardenSmart. Your river cruise begins in Amsterdam where you'll see works by Rembrandt and Van Gogh, Anne Frank's House, and see the city's most famous gardens. Then spend a full morning on the grounds of the most beautiful spring garden in the world-Keukenhof! Visit the picturesque Belgian towns of Bruges and Ghent as well as Kinderdijk, with the Netherlands' iconic collection of 19 authentic windmills that is a UNESCO World Heritage Site. In addition, history buffs will experience a captivating tour of the WWI trenches of Flanders and WWII Arnhem Battlefield of A Bridge Too Far fame. You won't want to miss this extraordinary garden adventure to Holland and Belgium.

Book by November 15, 2017 and save up to $1200 dollars per person!

To register call: Alki Tours at 800-895-2554

  Click here to sign up for our monthly NEWSLETTER packed with great articles and helpful tips for your home, garden and pets!  
Copyright © 1998-2012 GSPC. All Rights Reserved.