When you think of fruit production in Florida, blackberries (Rubus spp.) will not quickly jump to mind. Many people envision viny plants infiltrating your gardens and attacking you with their tiny spines. These are dewberries and are not known for large or consistent fruit. Though scientifically of the same name, bush varietals are a world apart. Bush blackberries fall into the rosaceae or rose family. They are deciduous fruiting shrubs, generally acclimatized to temperate environments. Luckily for us, they grow in the Panhandle. They’ve not taken off as an agronomic crop large scale due to the brittle nature of their fruit. However, with estimated production rates of 6000lb per acre many parts of the country, their value in home food production is undeniable.
UF/IFAS photo: Brent Sellers
Which to Pick
The University of Florida has been heavily breeding blackberries, but as with all gardens, plant selection is vital. The most critical factor in selecting blackberries is the chill hour requirement. You may recall that chill hours are the total time below 45 degrees a plant needs to set fruit the following spring. The vast majority of our area gets 660-700 chill hours per year on average, with the extreme north end getting upwards of 800 hours yearly. Once this is determined, the focus shifts to growth habit. Many grow erect and will not need trellising, but there are cultivars that vine and will need support. A final consideration for cultivar selection is whether or not they will need pollinator plants as an accompaniment. If the berries you want have this need, pick a compatible cultivar with a similar bloom time. Some cultivars that will do well in north Florida include ‘Arapaho,’ ‘Chickasaw,’ and ‘Choctaw.’
UF/IFAS photo: Mary Salinas
Planting and Care
Plant blackberries over the winter months much as you would any deciduous fruits. If you must store the plant before planting, keep the roots moist if you will be holding the plant for any amount of time. Ensure the first main root is just above the soil line, and remove any air pockets as you backfill the planting hole. Keep the soil moist but not overly wet, and avoid overhead watering. Space the plants according to their full size, which varies based on cultivar. These have shallow root systems and are therefore not heavy feeders. As a result, apply nutrients in the spring of the year they’re planted at ¼ pound per plant. In subsequent years apply ¼ to ½ a pound per plant twice a year. Irrigation and weed control will also be critical in their first year. Irrigation will become less important once the shrubs establish in their location.
Growing food in your home landscape is a great way to reconnect with your property and bring your food system as local as possible. Blackberries are low-maintenance fruit that, once established will provide years of production with minimal effort. For more information, see this Ask IFAS document. Contact your local extension agent for additional information on this and any other topic regarding your gardens.
Blackberries are one of the easiest fruiting crops to grow in the North Florida garden. Fruits mature during the month of May and early June. If you don’t plan to eat your blackberries fresh, learn some quick tips from UF IFAS Escambia County Extension for saving blackberries for a special treat later in the season.
Ripening thornless blackberries. Photo credit: Mary Salinas, UF/IFAS Extension.
To everyone’s delight, the blackberries are ripening in the Santa Rosa County Extension demonstration garden. The blackberry patch is a reliable perennial that continues to provide fresh berries year after year. Before you decide against them because you don’t want a thorny and painful hazard in your landscape, remember that there are thornless blackberry cultivars with fruit just as tasty as the old-fashioned thorny blackberry varieties. However, it is important to take care and make sure that the variety or cultivar you choose is adapted to our Florida climate and chill hours.
Blackberries bloom and produce fruit on last year’s canes. This year’s growth (the bright green shoot in the front center) will produce next year. Photo credit: Mary Salinas, UF/IFAS Extension.
You can choose a blackberry variety from your local nursery or propagate some plants from a favorite blackberry grown by a friend or neighbor (with permission, of course). Methods of propagation include stem cuttings, root cuttings, tip layering and removing the suckers that arise from the roots.
Plant when the weather is cooler in winter and choose a sunny spot with good soil. Frequent irrigation is crucial during the establishment period and when the fruit is produced. Weed control with organic or plastic mulches is also important to the success of your blackberry patch.
For more information on blackberry cultivars, propagation and growing success please see the University of Florida publication The Blackberry.
Although blackberries are well adapted to North Florida, many different biotic and abiotic factors can impact fruit production. Photo by Molly Jameson.
Diagnosing Abiotic Blackberry Fruit Disorders
Whether it be wild blackberries you’ve foraged or a prized cultured variety you’ve oh-so-carefully sustained, we are now in prime blackberry season, and there are many sweet, tangy delectable fruits to be eaten.
Blackberry bushes are well adapted to the Florida Panhandle and the plants can be found growing all over – along roadways, in ditches, throughout open fields, and also within forests.
Although wild blackberries and domesticated cultivars thrive in our climate, there is a wide range of factors that could affect blackberry fruiting. When diagnosing plant problems, we tend to blame insects and diseases, but there are many abiotic (non-living) factors that could negatively impact blackberry fruit production. If your blackberry drupelets (the small subdivisions that comprise a blackberry fruit) are compromised, you may be experiencing one or more of the following abiotic blackberry disorders.
Although blackberries can self-pollinate, insect pollination is critical for forming the best blackberries. Photo by Johnny N. Dell, Bugwood.org.
Poor Pollination. Blackberries, strangely enough, are not true berries botanically. True berries only have one ovary per flower (such as bananas, watermelons, and avocados!). Each blackberry flower contains over 100 female flower parts, called pistils, that contain ovaries. To form a fully sized blackberry with many drupelets, at least 75% of the ovaries need to be pollinated. While blackberries can self-pollinate, pollinator insects, such as bees, are very important to ensure adequate drupelet formation. When weather conditions are overly cloudy and rainy, bees are less active. If this coincides with blackberry flowering, you may end up with some blackberries that are nearly drupe-less.
White Drupe. If you notice patches of white and brown drupelets on your most sun-exposed canes, you might have white drupe disorder. When humidity drops and temperature heats up, solar radiation contacting your berries is more powerful, as there is less moisture in the air to deflect the intense heat. Berries that are not protected by leaf coverage, and those on trellises oriented for maximum sun exposure, are most vulnerable to white drupe damage.
Sunscald. Often associated with white drupe, sunscald is most common when temperatures are extreme. Daytime highs in the Florida Panhandle in June and July regularly reach 90°F, if not higher. At these times, fruit exposed to the sun can be hotter than the air temperature around them, which essentially cooks the fruit. As I suspect you’d prefer to cook your fruit after harvest in preparation for blackberry pie, orient your trellis so it gets shade relief during the hottest part of the day and harvest often.
Diagnosing a blackberry issue can be challenging, as there can be more than one culprit impacting the fruit. Photo by Molly Jameson.
Red Cell Regression. One of the not-so-well understood abiotic blackberry disorders is red cell regression, or red drupelet disorder. If you’ve ever harvested blackberry fruit and stored them in the refrigerator for later munching, you may think your eyes are deceiving you when you discover your fruit doesn’t appear as ripe as when you picked it. This regression in color is linked to rapid temperature change, but rest assured, it does not affect the sugar content of the fruit. There are a few things you can do if you think this is affecting your berries, such as harvesting in the morning when the berries are still cool, harvesting when the sky is overcast, or shading your berries pre-harvest. You can also try to cool your berries in stages, perhaps moving from the field, to shade, to A/C, and then to the fridge.
Beyond abiotic stresses, blackberries can also suffer from insect, pest, and disease damage, such as from stink bugs, beetles, mites, birds, anthracnose, leaf rust, crown gall, and beyond. For domesticated blueberry bushes, proper cultivar selection, site selection, planting technique, fertilization, irrigation, propagation, and cane training is important and will allow the plants to grow healthy to defend themselves against any abiotic or biotic nuisance that comes their way.
Every winter season in the Florida Panhandle is different. It can be wet or dry, frigid cold or unseasonably warm. We may have early frosts and early springs, or cold snaps in late march after fruit trees flower.
While we cannot determine the exact time to prune the dooryard fruit trees in our rather variable region, here are some tried and true guidelines for pruning the most popular edible garden plants in northwest Florida.
Blackberries
Blackberries are unusual in that they do not build a large structure and fruit for years on the same branches (in general). They actually fruit on previous years’ growth which then die after fruit production. The canes that produce fruit are called the floricanes. As the floricanes are producing fruit, the blackberry plants are growing primocanes. These are the new canes that will produce fruit for the next season. By then, these canes will have matured in to floricanes. A few new blackberry cultivars exist that produce fruit on new growth as well, but most Florida adapted cultivars are of the standard type. For pruning purposes, it is best to remove the floricanes just after fruiting, but be sure not to cut the new growth (primocanes) because that wood will bear next year’s fruit. For more information about the blackberry, please see publication HS807.
Blueberries
With blueberries older canes need to be removed to make room for younger, more productive canes. When a plant reaches four to five years old it is permissible to remove about 1/4–1/5 of the oldest canes each year which amounts to about one to three of the oldest canes. Performing this task will ensure that no cane is more than three or four years old. Thus, blueberry plantings will be in a constant state of renewal and not become excessively woody and nonproductive. To keep plants from becoming too tall, mature plants can be topped in the summer directly after fruit harvest. Removal of a few inches to a foot, depending on the cultivar, will stimulate the new growth that will bear the next year’s fruit. See CIR 1192 for more information
Temperate Fruit Trees
Pruning of temperate fruit trees (Peaches, Apples, Pears, Persimmons) should be done during the winter dormant period in most cases. This period, generally between December and February allows for some latitude. Pruning later in the dormant season is better in most seasons since trees are more susceptible to freeze damage after pruning, and pruning stimulates the growth of the trees. In Northwest Florida, a February pruning is usually most desirable, depending on the season (namely average high temperatures). Pruning for shape is also done in the summer months if necessary. This task should be limited to removing excessive growth and dead / diseased wood. See HS1111 and HS14 for more information.
Muscadines
Once harvest concludes, it is usually a grower’s natural inclination to immediately prune their muscadine vines. Pruning after harvest in early fall is not, however, best for maintaining plant condition and optimizing next year’s yield, especially if there is an early frost. Early frosts can surprise the plant before sugars have been moved to the roots for storage during dormancy. Therefore, waiting to prune in mid-January to mid-March will ensure that the vine has had adequate time to go dormant and acclimate to the winter season. For more information please see this article titled “Tips for Properly Pruning Muscadines”.
Citrus
Pruning is not necessary for citrus in every case, as it is in many temperate fruits, to have excellent production quality and quantity. Citrus trees perform excellently with minimal pruning. The only pruning necessary for most citrus is removing crossing or rubbing branches while shaping young trees, removing dead wood, and pruning out suckers from the root-stock. Homeowners may choose to prune citrus trees to keep them small, but this will reduce potential yield in a commercial setting, since bigger trees produce more fruit.
Often, maturing Satsuma trees produce long vertical branches. It is tempting to prune these off, since they make the tree look unbalanced. To maximize yield, commercial Satsuma growers allow these branches to weep with the heavy load of fruit until they touch the ground. This allows increased surface area for the tree, since the low areas around the trunk are not bare. Additionally, weeds are suppressed since the low branches shade out weed growth. The ground under the trees remains bare, thus allowing heat from the soil to radiate up during cold weather events. The extra branches around the trunk offer added protection to the bud union as well. If smaller trees are desired for ease of harvest, ‘flying dragon’ root-stock offers dwarfing benefits, so that the mature scion cultivar size will only grow to 8-10 feet tall.
Fig
Figs should be pruned after fruit production, which usually occurs in early summer. In the winter it is fine to remove dead or diseased wood, but drastic trimming will reduce yield since fruit is borne at the terminal of the previous year’s growth. For more information, please consult publication HS27.
