The secret to getting a good strawberry harvest in hot summer climates—where daytime temperatures are consistently greater than 85°F–is to have strawberries ready for picking in mid-winter, not in late spring or early summer as in cooler summer regions. Early spring is the traditional time to set out strawberries but where summers are hot, a spring planting will be disappointing.
Strawberries are easy to grow but can be difficult to grow well. Strawberries come to harvest after four or five months of growth. Well-established plants are the best producers. Where summers are hot, set out new strawberry plants in late summer so that they establish themselves in cooling not warming weather and are ready for harvest in midwinter; in the northern hemisphere set out plants in September for harvest in January.
Strawberries want to flower and come to harvest in cool to warm weather. The ideal temperature for strawberry growing is 60°F to 80°F; those temperatures allow strawberries to develop strong roots and take up nutrients necessary to produce lots of flowers and fruit. Weak plants will not produce a strong harvest and commonly will not survive summer heat–sustained temperatures of 85°F or greater. (That means a spring planting of strawberries in hot summer regions is a waste of time and effort.)
Here is a year-round growing strategy for strawberries in hot summer regions:
Late summer and fall. Plant strawberries in late summer when the days are cooling, but the soil remains warm. This is the time of year older plants will also begin to revive. Fall is not the usual time to find strawberries in nurseries or garden centers; you may have to call on strawberry growing friends to give you strong plants or established runners. Set plants into compost rich, well-drained ground at the same level they were growing before. Do not set the crown of the plant too high or it will dry out; do not set plant crowns too low or they will rot. Water transplants into place and adjust plants if they settle too deeply. Set plants about 12 inches apart allowing space for runners that will follow to fill in the bed.
Fall and early winter. Grow strawberries on during the cool time of the year. Keep the soil around establishing strawberries moist, but not wet. If leaves turn pale green with dark colored veins ease up on the watering. Water strawberries to a depth of 12 inches and then allow the soil to dry out for a few days. Adding aged compost around plants is the best fertilizer you can give them; you can never add too much compost to your growing beds. If you use a commercial fertilizer, choose one rich in phosphorus and potassium and be sure to follow the directions and not over feed plants.
When the weather turns cold, cover the bed with a portable plastic tunnel–a sheet of clear plastic (4 to 6 millimeters thick) set over a frame of half hoops or wire construction mesh; strawberries can withstand a few nights of frost, but not a sustained freeze. Be sure to ventilate the tunnel on warm days by opening the ends to fresh air. On freezing nights, put a tarp or blanket over the frame to keep it warm.
Strawberries will begin to flower and set fruit when the temperatures warm and days grow longer. If your strawberries are well established, you can expect plants to fruit abundantly until the temperatures climb into the high 80°sF.
Mid- to late-winter and spring. While the soil is still warm, spread straw around plants to keep the berries clean when plants set fruit. (You can also grow strawberries through plastic or garden fabric; set the plastic or fabric across the bed before planting.) Place straw around plants so that air can circulate beneath. When strawberries begin to ripen be sure to check them every day; pick fruit when it turns completely red but before it gets soft—it’s ok for the berries to be slightly white at the end; they will continue to ripen for a few days after picking. If you don’t need new plants, pinch away runners and let established plants grow stronger.
Summer. Shade the strawberry growing bed during the summer to reduce stress on plants and too keep plants from burning or drying out in the summer heat. Replace the clear plastic sheeting atop the hoop tunnel with 65 percent shade cloth, or place a thick layer of fresh straw atop the growing bed covering both plants and soil to keep the sun off the leaves. Again, water to a depth of 12 inches (you can check the water depth with a soil probe) allowing the straw to dry out between waterings; avoid too frequent waterings so that snails and pillbugs don’t get comfortable in the strawberry bed and mold does not begin to grow.
Year-round container growing. Hot summer region or any region, strawberries are suited for container growing. Mobile containers will allow you to take strawberries out of summer heat and winter cold. Select a container that is deep enough for strawberry roots—12 to 15 inches—and well drained. Terra-cotta or plastic strawberry pots with cup-shaped pockets around the sides are designed for multiple plants and a modest harvest. Water plants regularly, and feed plants weekly with a high potassium-low nitrogen fertilizer once flowering starts.