Any North Florida resident who has tried their hand at growing apples, peaches, or plums may occasionally find themselves frustrated by a year (or two…or three) with a poor or nonexistent harvest. What has gone wrong? Are the trees getting a disease? Were they not fertilized properly?
It may be that the tree owner has done everything correctly, but the weather is actually to blame. The answer to “what has gone wrong?” may lie with a concept called “chill hours”. Plants that are adapted to living in colder climates need some way to figure out when the winter is over. If a plant starts blooming too early, it’s likely that a frost will come along and knock out this year’s flowers. No flowers, no fruit. For a plant, this means no little baby plants this year to keep the species going. To avoid this, some plants have figured out a way to detect and keep track of how cold it’s been in a particular year. When enough hours of cold weather have accumulated, that’s usually a safe signal that spring must be near. This means it’s time to blossom when the weather next warms up.
Usually. Different varieties of plants are adapted to blossom at different times of year, depending on the average amount of cold weather the area they live in gets each year. A plant from a colder climate might not start growing flowers until it has detected 1,000 hours of cold…or more! Given that the temperature range that counts as a chill hour is around 32-45 degrees Fahrenheit, you might correctly guess that such varieties will NOT do well in Florida. In north Florida, we receive somewhere from 500-700 chill hours each year. This winter (as of February, 2023), we have received 479 chill hours in Walton County.
Chill hour total for Walton County, as of Feb 1, 2023
That’s not a lot, and we may not get much more weather that plants recognize as cold enough to count. Apple growers with varieties that need even as few as 500 chill hours may not be making many pies this year. So what can be done?
First, temper your expectations. Understand that even though we may get the occasional hard freeze, it may not count any more toward the chill hour requirement than temperatures just above freezing. Then, when it warms up the following week, those 70 degree temperatures may actually set BACK the chill hour clock for some plants.
Second, choose varieties that require few chill hours in the first place. A ‘Honeycrisp’ apple, needing 800-1000 chill hours each year, is probably never going to produce fruit in the panhandle of Florida. Other apple varieties might, though! Try varieties such as ‘Anna’ (which needs only 300 chill hours), ‘Dorsett Golden’ (250 hours), or ‘Tropic Sweet’ (300 hours). For peaches, try varieties like ‘GulfAtlas’, ‘Gulfcrimson’, or ‘Gulfsnow’ (400 hours each).
Third, consider learning to love other types of fresh fruit. Persimmons, figs, kumquats, and loquats may not show up very often in treasured family recipes, but they can offer a tasty alternative to plants that simply might not be well adapted to our climate.
Peaches are popular, but they may not produce fruit every year!
For more information, try these links:
To calculate how many chill hours your specific area has received, check out the tool at agroclimate.org.
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.
