Weather Talk

The Georgia FACES article "Polar Vortex brings unexpected winter storms to Georgia", by Sharon Dowdy, explains not only what caused the recent winter storms in Georgia, but also what we can expect, with regard to the weather, for the next several weeks.

Dowdy interviews UGA climatologist Pam Knox, who explains that the polar vortex, which usually stays up in the polar north through the winter, is an area of cold, strong, high winds and low pressure.

Knox said, “Usually it [the polar vortex] sits on top of the globe like a hat, but this year it has slid forward over the U.S.”  This year, she added, also has been a year of "high swings in temperature conditions."

Dowdy explains, "This unpredictability could cause havoc for Georgia farmers and gardeners this spring ... For instance, if Georgia fruit trees begin to flower and a late frost hits the state, the fate of peach, blueberry and other fruit crops will be threatened." 

Knox also cautions gardeners to not plant too soon, since the chance of a late frost is increased this year.

How late is a "late" last frost?

Here in Cobb County, we have become accustomed in recent years to the last frost's occurring in March, and warm enough temperatures for planting tender crops like peppers and eggplants in early April. UGA's Automated Weather Stations show, though, that the last frost has fallen in April in some years within the past decade or so.

These are the data for the last frost date from the two nearest UGA Automated Weather Stations for Cobb County -- one in Dallas, GA, at the Paulding County High School, and one in Dunwoody, at The Cherokee Town & Country Club:

Last Frost Date

Top of Form

From Jan-1 to May-31 Dunwoody Last Frost Date Dallas Last Frost Date 2013 Mar 28 Mar 28 2012 Mar 6 Mar 6 2011 Mar 12 Mar 12 2010 Mar 8 Mar 7 2009 Apr 8 Apr 8 2008 Mar 25 Mar 25 2007 Apr 9 Apr 9 2006 Mar 27 Mar 27 2005 Mar 18 Apr 24 2004 Mar 23 Mar 23 2003 Mar 31 Mar 31 2002 Mar 28 Mar 28 2001 Apr 19 Apr 19 2000 Apr 9 1998 Mar 23 1997 Apr 18 1996 Apr 11

Notice that in 2005, the two stations show very different last frost dates. Also, the weather station in Alpharetta (data not listed hear) showed a last frost date for 2012 of April 12, somewhat later than the Dunwoody and Dallas stations. The charts show that, not only can the last frost date shift by several weeks from year to year, but it also can vary across the metro area, and "late" can be very late indeed!

For Dowdy's complete article, with additional information provided by Pam Knox, click on the link here.

Pruning, Planting, Fertilizing

Such a busy time of year for the great outdoors here in Cobb County! Vegetable gardeners will have begun planting their summer crops within the last week or so; seedlings are coming up; early-flowering shrubs like azaleas will need to have any pruning done very soon; and the warm-season lawns (Bermudagrass, Centipede, Zoysia, St. Augustine) should have any needed fertilizers applied within the next several weeks.

Zucchini seedlings emerging.                               PHOTO/Amy Whitney

Vegetable gardeners who would like to verify that planting time is now for most of the summer crops can check UGA's Vegetable Planting Chart. The planting dates on the chart are for middle-Georgia, so the dates should be adjusted by a week or two for Cobb County.

With regard to pruning the azaleas, UGA's Frank Watson reports in the 25 April issue of FACES that azaleas should be pruned "now, after they have bloomed, to allow the plants to prepare for blooming next year."

Watson's article explains the two pruning techniques typically applied to azaleas - thinning cuts and heading cuts:

"Thinning refers to the complete removal of branches back to another branch or main trunk. Thinning is used to remove leggy branches that extend beyond the canopy of the plant, to reduce the size of the plant or to remove any damaged or diseased wood. Thinning can be done any time of the year without significant impact on flowering, growth or cold hardiness

"Heading refers to the cutting back of a branch, not necessarily to a side branch. Vigorous new shoots will emerge within 6 inches of the pruning cut. Heading is usually done with three goals in mind: to reduce the size of the plant, to increase the number of branches or to rejuvenate old, overgrown plants. Severe pruning of old, overgrown plants to within 6 to 12 inches of ground level is a common type of heading."

For more information, refer to Watson's article "Azalea Bloom Show is Over so It's Time to Prune and read UGA's "Selecting and Growing Azaleas."

Upcoming Events

Right Plant in the Right Place
Wednesday, March 13, 6:30 - 7:30 p.m. Free and open to the public. Presented by Cobb County Master Gardener Joe Washington, at Mountain View Regional Library on Sandy Plains Road in Marietta, as part of the ongoing Gardeners Night Out presentation series of Cobb County Cooperative Extension's Master Gardener Volunteers of Cobb County.

Plant Pick-up for 4- H Plant Sale
Saturday, March 16, 9:00 a.m. - 3:00 p.m. Pick up plants ordered through the annual 4 -H Plant Sale at Jim Miller Park on Callaway Rd. in Marietta. For information on planting and care of your new plants, contact Cobb County Cooperative Extension at 770-528-4070 or uge1067@uga.edu.

Vegetable Gardening Basics
Tuesday, March 19, 6:30-8:00 p.m. Free seminar for beginning gardeners covers the basics of vegetable gardening here in Georgia. Presented by Cobb County Cooperative Extension. Horticulture Program Assistant Amy Whitney will provide the information you need to get your garden off to a good start. Presentation will be at Cobb County’s Cooperative Extension Office, 678 South Cobb Drive, Marietta, 2^nd floor classroom. Preregister by calling 770-528-4070 or email uge1067@uga.edu.

From Your Garden to Your Table
Tuesday, April 2, 6:30 - 8:30 p.m. Cobb County Cooperative Extension staff will provide gardening tips for growing abundant produce for your family and for safely preserving that abundance through canning and freezing. Event will take place at Cobb County Cooperative Extension, 678 South Cobb Drive, Marietta. Cost $10 at the door (cash, check, or money order, payable to Cobb 4-H). Preregistration required; call 770-528-4070.

Ikebana: Japanese Flower Arranging
Tuesday, April 9, 6:30 to 7:30 p.m. Free and open to the public. Presented by Donna Scott at the South Cobb Regional Library on Clay Road in Mableton, as part of the ongoing Gardeners Night Out presentation series of Cobb County Cooperative Extension's Master Gardener Volunteers of Cobb County.

Starting Your Spring Garden
Tuesday, April 9, 6:30 - 8:00 p.m. Free and open to the public. The second in the 2013 series of classes sponsored by The Green Meadows Preserve Community Garden. Presented by Cobb County Cooperative Extension staff member Amy Whitney, who will provide gardeners with the basics of what, how, when and where to plant in the areas available to them. Event will take place at the smaller Parks and Recreation building near the Boots Ward Recreation Center at Lost Mountain Park, 4845 Dallas Hwy.

Tomatoes: From the Turtle to the Table
Friday, April 12, noon to 1:00 p.m. Free and open to the public. Presented by Cobb County Master Gardener Renae Lemon at the County Water Lab at 662 S. Cobb Drive (the smaller brick building at the back of the property), as part of the ongoing Lunch & Learn presentation series of Cobb County Cooperative Extension's Master Gardener Volunteers of Cobb County. Renae will tell all you need to know about growing tomatoes.

Algae Control in Ponds
Wednesday, April 17, 8:30 a.m. - noon. Instructed by UGA Aquaculture Specialist Dr. Gary Burtle, at Cobb County Cooperative Extension, 678 South Cobb Dr. in Marietta. The workshop will present information about the composition of scum and blooms seen in ponds, their causes, and ways to control or reduce their intensity. Participants are welcome to bring water samples for identification of algal species or water analysis. Re-certification credits: Category 26 Aquatic Pest Control - 3 credits; Private Applicator License - 2 credits.Cost $5 at the door; refreshments provided. Seating is limited. Preregister by calling 770-528-4070.

When Should I Plant Peas and Potatoes?

Especially after a relatively mild winter like the one we've been experiencing, impatient gardeners are beginning to feel as though it must be just about planting time for some of the cool weather vegetables. The impatient gardener here in Cobb County would not be wrong.

UGA's "Vegetable Planting Chart," (document is a pdf) linked through its "Vegetable Gardening in Georgia" publication, shows planting dates for middle Georgia that need to be adjusted by a couple of weeks for our area, but the opportunities for planting are about to become numerous! However, for the best chance of planting success in an unusual winter, any date-based chart should be double-checked against other factors.

For peas and potatoes, which are among the earliest-planted vegetables in the spring garden, soil temperatures provide a valuable guide. What does soil temperature have to do with planting time? If the soil is too cold and wet, seeds and seed potatoes set out to grow will, instead, rot in the ground.

Vermont's Cooperative Extension includes a helpful note for gardeners concerning soil temperature and early spring planting in its publication "Planting Peas and other April Gardening Tips" :

"One of the first crops you can plant in the spring are peas.  This vegetable thrives in cool, moist climates with early plantings normally producing greater yields than plantings later in the season.  Wait until the soil temperature is at least 45 degrees F, then plant seeds one to two inches deep and one inch apart in single or double rows."

Potatoes do best when planted with a similar temperature minimum.

Our soils warm up to 45 degrees and above way before April, but the basic rule still applies. The good news for us is that Georgia's Automated Environmental Monitoring Network shows that soil temperatures at the weather station in Dallas already are about 45 degrees F, while soil temperatures at the weather station in Alpharetta are still below 43 degrees F.

Looks like pea and potato time is just about here.