Understanding Chill Hours

Understanding Chill Hours

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.

For information on apples, peaches, plums, blueberries, or other fruits, try our EDIS publications on each.

You can also, of course, contact your local Extension office for help as well!

Evan Anderson

Walton County Horticulture Agent

A Nice Cup of…Camellia?

A Nice Cup of…Camellia?

Residents of North Florida are no doubt familiar with camellias, the large, glossy-green-leaved shrub that flowers during the cooler seasons. Common varieties include Camellia sasanqua, which blooms from October through December (depending on variety), and Camellia japonica, which blooms January through March. Both make huge, showy blossoms that demand attention, with forms that range from wild-rose-like to stunning geometric formal patterns.

The popularity of these shrubs is not in doubt, but a cousin of theirs takes the prize as one of the most popular plants in the world. Not due to its flowers: this variety of camellia does bloom, but the leaves are most interesting to humans. It is grown in dozens of countries worldwide and global production is estimated at over $17 billion worth of these leaves. The primary product made from this plant is a beverage that is consumed more than any other drink except water. It is, of course, tea.

Camellia sinensis or “Tea Plant”. Photo courtesy of UF/IFAS.

Camellia sinensis was named by botanist Carl Linnaeus, “Camellia” to honor another botanist, Rev. Georg Kamel, who really had nothing to do with the plant at all, and “sinensis”, which means “from China”. You may be able to deduce where tea is native to.

The tea plant prefers temperatures from 65 to 86 degrees Fahrenheit, doing well in zones 7-9. It can survive freezing or slightly-below-freezing temperatures, though leaves may be damaged by frost. It enjoys moist conditions, needing around 50 inches of rainfall per year. China tea (variety sinensis), which produces smaller, more serrated leaves, prefers more light than Assam types (variety assamica), which have larger, less serrated leaves. Either variety can be grown as a shrub or small tree.

Propagation may be accomplished either by seed or cuttings; cuttings are the preferred method for reproduction, as seeds must be germinated before the seed coat hardens for best results. Caring for tea plants once established involves more frequent but light fertilization, mulching, and regular scouting for pests. Camellia sinensis is susceptible to mites, thrips, scale insects, and aphids, all of which are present in large numbers in our area. Luckily, most of these problems can be solved with an application of either insecticidal soap or horticultural oil, if control is even necessary.

Once a tea plant is large enough to harvest leaves from, it is the new growth which is plucked. The top 2-3 leaves are used either fresh or fermented for a period of time before they are brewed. Green tea comes from the fresh leaves of China type tea plants, while either China or Assam types may be used to make black tea. Black tea leaves are picked, wilted or crushed, and allowed to ferment. Fermentation darkens the leaves and is halted by heating, which also serves to dry the leaves for storage.

For more information on the tea plant, see our EDIS publication on Tea Growing in the Florida Home Landscape.

Camellia sinensis foliage. Where the tea is made! Photo courtesy of UF/IFAS.
The Benefits of Turfgrass

The Benefits of Turfgrass

Turfgrass lawns are popular. Homes and businesses alike often have at least some portion of their landscape dedicated to turf, and while it is often maligned, turfgrass does have some benefits when used and managed responsibly.

Well-managed turfgrass, like this centipedegrass lawn, can be a sustainable and attractive option for landscapes. Photo credit: Dr. J. Bryan Unruh, UF/IFAS

Detractors of lawns may argue that lawn maintenance uses water, gasoline (for mowers), and pesticides, all while contributing little to the environment. The varieties of grass we use in the Florida panhandle are not native to the area, with the possible exception of St. Augustinegrass. Planting anything – and especially non-native plants – in a monoculture limits biodiversity and does not support native wildlife. These complaints may be valid in cases, but this does not mean there is no room for turfgrass in the landscape. Instead, it is important to design landscapes appropriately and maintain lawns sustainably. The ideal of a lush, completely weed and insect free, beautifully green all year long, neatly trimmed magazine-cover style swath of grass is unrealistic.

That being said, what are lawns useful for? What are the benefits of turfgrass?

When managed properly, turfgrass can be used for numerous beneficial reasons. Grass is a plant, which means that it has roots to stabilize soil, slow runoff, and filter water. It keeps down dust, mitigates heat, and can outcompete unwanted weeds. It is useful as a surface for recreation, and can add aesthetic value to a landscape. Turf does, in fact, support wildlife to a certain degree as well, as the insects that live in and feed on it can serve as food for birds and other animals.

Improper irrigation can cause big problems with turf and lead to wasted water, but turf can help to slow down runoff and absorb excess nutrients.

Artificial turf is sometimes considered as an alternative to grass, but the differences can serve as an example of the benefits of turf. Artificial turf can heat up in the hot Florida sun. Where it is used on athletic fields, it may need to be irrigated to both cool it and keep dust down. The water used for this has much more opportunity to run off the site, as the artificial turf has no roots to slow it down. Turfgrass is also much softer than its man-made replacements; sports fields with artificial turf have a higher incidence of injury than those planted with grass.

Lawns must be managed well, however, as has been stated before. Proper species selection (whether bahia, centipede, Bermuda, St. Augustine, or Zoysia), establishment, irrigation, fertilization, and mowing practices all contribute to making turfgrass a sustainable option. You can find information on all of these in our EDIS publications, which are linked to above, or contact your local Extension office for help. If turfgrass still seems like an unpalatable option, you can also find information on turfgrass alternatives and more on Florida Friendly Landscaping. Keep your expectations reasonable and your landscapes sustainable!

What’s that Webbing on My Tree Trunk?

What’s that Webbing on My Tree Trunk?

There are numerous insects and insect relatives that can produce webbing, and webbing can be a sign that something unwanted is near. Arachnophobes might grow uneasy at the sight of a spiderweb, and gardeners might frown to see the tiny filaments that spider mites spin. Tree lovers might assume that webs on a tree are a sign that caterpillars such as the eastern tent caterpillar have taken up residence. But what about webs on a tree trunk?

Bark louse webbing. Photo courtesy of Evan Anderson.

If you come across a tree trunk coated in silk, chances are you’re looking at the work of a bark louse. Also known as psocids or tree cattle, these little insects eat all the stuff that sticks to a tree’s bark. Lichen, moss, algae, and dead bark can all end up as meals for a hungry bark louse. The good news is that while lichens don’t hurt trees, neither do bark lice!

Bark lice spin their webbing as protection from predators. They often produce large quantities of webbing, because there are often large quantities of bark lice present. The name ‘tree cattle’ comes from the fact that they form these large colonies, and move in a manner similar to cattle in groups. While swirling swarms of creepy-crawlies rarely make people feel at ease, don’t worry about these. Acting as a sort of clean-up crew, they will do their work, grow and mature, and move elsewhere by themselves.

There are often several generations of bark lice each year in Florida, so they may reoccur. No control is needed for these insects, though if leftover webbing is considered aesthetically unpleasing it can be removed by spraying with a sharp jet of water. For more information about bark lice, see our EDIS publication at https://edis.ifas.ufl.edu/publication/IN553.

Bark louse nymph. Photo courtesy of Evan Anderson.
Vegetables for the Summer Heat

Vegetables for the Summer Heat

Unlike areas with cooler climates, North Florida’s weather is a bit of a rollercoaster. Where the traditional four seasons allow for one growing season, the panhandle’s temperature changes create two growing seasons – spring and fall. During the winter, temperatures fall too low to keep plants happy, so those who expect to grow tropical plants in Florida may be disappointed. During the summer, the heat and humidity climb to levels that even plants can find stressful! Many of our vegetable crops simply can’t handle the extremes and wither away.

There are a few edible plants we can grow, however, that don’t seem to mind the hot weather. If you simply can’t live without a productive garden during the summer, you might consider trying these:


Also called Southern peas, black-eyed peas, or field peas, these are known for their ability to produce a crop despite the harshest of conditions. Actually a bean rather than a pea, they take 65 to 125 days to grow to full maturity, depending on variety. Because they are a nitogen-fixing legume, they have also been used as a cover crop.

Malabar Spinach

Malabar Spinach. Photo Credit: James M. Stephens, UF/IFAS

Popular in Asian countries, Malabar spinach is actually a vining plant unrelated to true spinach. It grows quickly and is edible both raw and cooked, though some people may not appreciate its mucilaginous texture. Similar to okra’s sliminess, this quality does make it useful for thickening soups. Malabar spinach may be propagated from seed or by cuttings, which root easily. The plant also produces berries which, while not toxic, have very little flavor and tend to stain whatever they touch.


A traditional Southern favorite, okra takes the heat and keeps producing. Related to cotton and hibiscus, it grows pods that are ready to harvest after 60-70 days. Seeds have a tough exterior and need to be soaked overnight before planting. Harvest every couple of days at least for best results, as pods that grow too large become tough and fibrous.

Seminole Pumpkin

A Seminole pumpkin. Photo credit: UF/IFAS

Though they may need extra attention paid to them due to their attractiveness to pests, Seminole pumpkins are a great option for a summer planting. Similar to butternut squash, these cucurbits aren’t your traditional carving pumpkin, but they make great eating. Give them plenty of room to spread out in a sunny space. They take 120 days after planting before they’re ready to harvest, and their thick skin allows them to be stored for a long time after.


Sweet Potato

Does well in sandy soil? Check. Doesn’t mind the heat? Check. Sweet potatoes are great for our neck of the woods. Start out with disease-free slips for best results, and pick varieties such as ‘Beauregard’ that do well in our area.

Yardlong Beans

Related to cowpeas, yardlong beans grow on a climbing vine. The beans themselves, as the name suggests, are contained in a pod that can reach 36 inches in length. These can be picked and cooked much like green beans while the pods are still tender.