Master Gardener Gardening Bench: Strawberries
By John Dawson, Master Gardener Volunteer 2007
Here in Central Florida, now is the time to plant strawberries. Find more articles on exciting topics here.
The home garden strawberry, Fragaria × ananassa, is a hybrid species that was first bred in Brittany, France in the 1750s via a cross of Fragaria virginiana (common wild strawberry) from eastern North America and Fragaria chiloensis, a wild strawberry which came from Chile in 1714. There are hundreds of varieties that have been developed since.
The berries of the strawberry plant (which aren’t true berries – it’s a bit complicated) are a complex arrangement of ovaries (the part which looks like seeds) sitting on top of a fleshy pulp which is actually part of the remaining flower receptacle. The actual seeds are inside the ovary casings. So in essence, the strawberry carries its seeds on the outside of the fruit instead of inside. Strawberries are classified as “June-bearing” strawberries – which bear their fruit in the early summer – and “ever-bearing” strawberries which often bear several crops of fruit throughout the season. The three basic flowering habits are short-day, long-day, and day-neutral, which refer to the day-length sensitivity (photoperiod) of the plant, which in turn affects flower formation. Day-neutral cultivars produce flowers regardless of the photoperiod (ever-bearing).
Strawberries require temperatures between 50and 80°F and day lengths of at least 8 to 14 hours of full sun for the development of flowers and fruit on most varieties. Successful varieties are bred specifically for their local environments. (So, rethink ordering plants from a grower up North! Buy from local Central Florida suppliers.) The University of Florida suggests three varieties for the Florida home garden: ‘Camarosa’, ‘Sweet Charlie’, and ‘Festival’. ‘Festival’ has been the most productive variety in Central Florida, producing 1 to 2 pints of fruit per plant per season. Strawberries should be grown in soil which is well drained and slightly acidic (pH 5.5-6.5). If your soil pH is within this range, you may grow your strawberries in standard mounded rows. If not, you may grow them in raised beds, boxes, pots or hydroponically, where you have greater control of soil pH. These methods are also best where growing space or soil nematodes are an issue. If you plan to grow more than a few plants, my preferred method is a raised bed pyramid, using landscape timbers.
To build a strawberry pyramid:
- Prepare a planting site for your strawberries at the beginning of September in a full-sun location.
- Build the planting beds, with landscape timbers, in dimensions that suit your needs.
- Fill the planting bed 1/2 to 2/3 full with a well-draining top soil. Mix in 3 to 4 inches of organic compost or peat moss to increase the nutrient value and water-draining ability of the bed.
- Test the planting soil pH (at the Extension Office). If necessary, work ground rock sulfur into the soil to lower the pH number according to directions on the bag. Water the planting bed well after making amendments and let it rest for two weeks.
- Plan to plant the strawberry plants 18 inches apart, with plants spaced alternately from those in other tiers.
- Dig planting holes that are deep enough for the plant roots to spread out (about 5 to 6 inches).
- Set the plants into the holes, spread the roots, and make sure the crowns are held above ground level. Gently cover the roots with soil and tamp down to hold in place, leaving no exposed roots.
Now would be a great time to add drip irrigation to your pyramid designed to soak the soil, not the leaves. Spread clean straw mulch (hence the name strawberries) around the plants to assist with soil moisture retention and prevent weed growth (black plastic also works well). Straw mulch will decrease berry rot by keeping the leaves from sitting directly on the soil. Water the strawberries after planting by moistening the soil to a depth of 6 inches. Apply water to the soil instead of spraying it on the plants. Do not create pooling of water around the plant stems, as this promotes root and stem rot.
Care and Maintenance:
Remove the plant blossoms that appear during the first year. This will promote plant growth during the first year when you want to develop good roots not berries. In turn, this will increase berry production the following years. (Commercial growers treat strawberries as annuals and skip pinching off, allowing the plants to fruit and then discard them. If you can’t wait, then pinch off only a portion of the plants and allow the others to fruit.) Strawberries propagate themselves by either sending out runners (stolons) which extend away from the parent plant and find a new area to establish roots for a new plant, or by the many seeds on the berries. You can control the placement of stolons by allowing them to root in an area you want, pinned in place in a pot for transplanting elsewhere, or simply removing them. Allowing the plant to develop runners takes energy away from fruit development. Seeds are spread by consumption (mostly birds.)
Strawberries are ripe when about 75% of the berry turns red (a cue for birds!) To protect your ripening berries, you will need to cover them with bird netting as they begin to turn color (the netting does not prevent theft by small family members.) Strawberry plants are attacked by over 200 insect pests and a number of diseases (mostly fungal based). Frequent scouting for insect pests and a regimen of fungicide application should keep plant loss to a minimum. Plant bed sanitation and weed removal is essential in maintaining healthy crop production. Strawberries should be protected from freezing temperatures by covering with frost cloth. For more information on Growing Strawberries in the Florida Home Garden go to http://edis.ifas.ufl.edu/hs403.
If you are allergic to strawberries, try pineberries, a strawberry cultivar that came to the European market in 2011 and that does not contain the gene for turning the berry red (found to be the primary cause of allergic reactions). The pineberry – from “pineapple” and strawberry” – is the result of cross-breeding, not genetic engineering. Pineberries were bred from a species of South American wild strawberry which was nearly extinct until 2003, when a group of Dutch farmers banded together to save the plant using source stock discovered in France. When ripe, it is almost completely white, but with red seeds. Strawberry thieves leave it alone because it never turns red.