Gardening in Arkansas: zones, frost dates and when to plant

Highlands and lowlands

Arkansas sits close to the Gulf of Mexico without touching it. The NOAA state climate summary describes the result as hot, humid summers, short and cool winters with occasional blasts of arctic air, and abundant rain all year, with winter and spring the wettest seasons.

The biggest difference inside the state is elevation. The Ozark Mountains cover northern and western Arkansas, and parts of the Boston Mountains top 2,500 feet. The summary compares two stations: the July average high is 83°F at Deer, at 2,375 feet in the northwest, and 91°F at Jonesboro, at 260 feet in the northeast. Winter follows the same pattern. Average January lows are coldest in the northwest, milder in the northeast and mildest in the southwest.

Arkansas Extension does not rely on USDA zones for planting. It splits the state into five lettered frost zones, A through E, each with its own average last spring freeze and first fall freeze, and its planting charts are written for central Arkansas. The University of Arkansas at Pine Bluff’s Year-Round Home Garden Planting Chart (MP422), for example, is built for zones B and C and tells gardeners elsewhere to shift dates earlier or later. Use the frost dates for your city above in the same way.

Two seasons, with fall the one people skip

Planning a Vegetable Garden in Arkansas calls stopping after the spring harvest a missed opportunity. Many spring crops grow as well or better in fall, and yields and quality are often higher, although insects and diseases can be worse in early fall. Extension’s fall planting chart shows how early fall planting starts: tomato plants and sweet corn go in during early July, southern peas, Irish potatoes and summer squash follow in mid-July, and carrots, broccoli, collards, cabbage and turnips run from August into September. MP422 adds that for fall tomatoes, broccoli, cabbage and cauliflower, seed should be sown about four weeks before the transplant date, which means starting seedlings in the heat of summer.

The planning guide also suggests successive plantings, since some vegetables can be sown nearly every month. Interplanting is another option: set tomatoes, peppers, eggplant or okra between rows of early cool-season crops, which will be harvested before the warm-season plants need the room.

Heat and the summer tomato gap

Tomatoes are the most popular garden vegetable in Arkansas, according to the Extension tomato fact sheet (FSA6017), and they show the state’s main summer limit. Extension’s tomato guidance puts ideal conditions at days in the 80s and nights in the 50s or 60s. When it gets hotter, fruit set drops. Spring fruit that sets at 55°F or below often comes out misshapen and poor. Cherry types keep setting fruit in heat that shuts down large-fruited varieties.

A July planting for fall is the usual workaround. Extension notes these plants grow vigorously, escape early-season diseases and often bear better fruit than a late picking from spring plants. Time them for about 100 days from transplanting to the first killing frost.

The fact sheet’s recommended cultivars include Better Boy, Celebrity, Mountain Pride and Big Beef among red slicers. It also lists the pink Bradley and Arkansas Traveler 76, Plum Dandy and Viva Italia for paste, and Juliet and Super Sweet 100 among small-fruited types. Several carry resistance to Fusarium and Verticillium wilt, and Better Boy and Celebrity are also listed with nematode resistance.

Water, drainage and dry spells

Arkansas rain is abundant on average but not reliable. The climate summary notes severe droughts in 2005 to 2007 and 2010 to 2012, and every county received a drought disaster declaration in 2012. Extension’s tomato guidance calls for a thorough watering every two to four days in dry periods, applied so leaves are dry by evening.

Drainage matters just as much. The Home Gardening Series (FSA6001) defines a well-drained soil as one where water does not stand more than 24 hours after a hard rain, with at least 8 to 12 inches of topsoil and no shallow hardpan. Where that is missing, the planning guide recommends raised beds at least 12 inches deep, set over ground that drains and no wider than you can reach to the middle.

Free soil testing

FSA6001 points out that you cannot know how much fertilizer a garden needs without a soil test. Arkansas Extension tests soil free for residents: take about one pint of air-dried soil to your county Extension office. The test does not report nitrogen, which varies too much, but it covers lime and other nutrient needs. Tomatoes, for instance, do best between pH 5.8 and 7.2.