by Eddie Powell | Jan 22, 2015
Florida homeowners enjoy a wide range of landscape and citrus plants and often times desire a tropical or semitropical appearance to their landscapes. Many landscape plants are often planted past their northern limit such as here in Northwest Florida, although microclimates differ dramatically. Tropical and subtropical plants can be used in the landscape, but they must be protected or replaced if necessary during cold weather. A good variety of tender and hardy plants should be planted in order to prevent total devastation of the landscape by extremely cold weather.
The site selection for tender plants should be number one on your list when preparing for a freeze. Tender ornamental plants need a higher site with good air drainage, and not in a low area where cold air settles. Arranging tender plants along fences or other barriers to protect them from cold winds improves the plants’ cold protection, especially from very hard freezes.
Poorly drained soils result in weak shallow roots which are more susceptible to cold injury. Plants grown with the correctly applied rate of nutrients will tolerate colder temperatures better and recover from cold injury faster than plants grown with little or no added nutrients. Be aware that late fall fertilizing of nutrient deficient plants or fertilization before unseasonably warm periods can result in a late growth which is more susceptible to cold injury.
Ornamental plants that are planted under large tree canopies can have more cold protection and require less cold prevention for the owner.
Watering landscape plants before a freeze can help protect plants. A well watered soil will absorb more solar radiation than dry soil and will reradiate heat during the night by as much as 2°F . However, saturated soil conditions can damage the root systems of most plants over a few days, so make sure the ground is well drained.
Avoid late summer or early fall pruning which can alter the plant hormonal balance resulting a flush of new growth. This new growth is more susceptible to cold injury. Healthy plants are more resistant to cold than plants weakened by disease, insect damage, or nematode damage. Routine inspection for pests and implementation of necessary control measures are essential.
Here are a few methods for plant protection. Plants in pots or containers must be moved indoors where heat can be available to them. Containers that have to be left outdoors should be protected by mulches around the container or root ball of plants in the landscape to reduce heat loss from container sidewalls.
Cold Protection for Veggies!
Coverings can help protect plants more from frost than from extreme cold. Covers that extend to the ground and are not in contact with plant foliage can lessen cold injury to the plant. Foliage in contact with the cover is often cold burned or injured because of heat transfer from the foliage to the colder cover. Some examples of excellent plant covers are cloth sheets, quilts or black plastic. If plastic covering is used, it is extremely important to remove the covering during the day to provide ventilation of trapped heat. A light bulb under a covering also is a simple method of providing heat to ornamental plants in the landscape during the night hours.
Cold Damage on Fruit Tree
Pictures By Eddie Powell
Immediately after the frigid weather has passed, plants need to be checked for water loss. The foliage could be losing water vapor or transpiring on a sunny day after a freeze while water in the soil or container medium is frozen. Apply water to thaw the soil and provide available water for the plant. Soils or media with high soluble salts should not be allowed to dry out because salts would be concentrated into a small volume of water and can burn plant roots. Root burn can cause the roots to dry out and not take up water to the plant.
Pruning should be delayed until freezing temperatures have risen or until new growth appears to ensure that live wood is not removed. Dead, unsightly leaves may be removed as soon as they turn brown after a freeze if a high level of maintenance is desired. But it is best to wait until the threat of freezing weather is gone. Cold injury may appear as a lack of spring bud break on a portion or all of the plant, or as an overall weak appearance. Cold injury is usually found in the upper portion of the plant. Branch tips may be damaged while older wood underneath is free of injury. Cold injured wood can be identified by examining the cambium layer under the bark for black or brown coloration. Prune these branches back to a bud 2-3 inches behind the point of discoloration.
For more information on freeze protection of plants see:
Cold Protection of Landscape Plants
by Sheila Dunning | Dec 23, 2014
A frozen perennial plant. Photo credit: Taylor Vandiver UF/IFAS Extension.
When you look out at your landscape nobody has to tell you that winter temperatures in Northwest Florida Afterwards, the temperatures warm up and you feel compelled to do something about it. You just need to “turn your back and slam the door”. “Conceal, don’t feel; don’t let them know”. Cold injury can affect the entire plant or just certain plant or parts such as fruits, flowers, buds, leaves, trunks, stems, or roots. Many plant parts can adapt to tolerate cold. Root systems in the landscape are seldom ‘frozen’ in Florida. “The cold never bothered” them “anyway”. While dead, unsightly leaves may be removed as soon as they turn brown after a freeze, the remaining dry looking stems serve as food storage and should be allowed to remain. If they are removed before the weather is warm enough for the plant to resume growth, the root system may not be enough to support the plant and it will die. So, “let it go, let it go, let it go”. “The perfect” landscape “is gone”. “The past is in the past”. “It’s funny how some distance makes everything seem so small”.Tropical plants and summer annuals do not adapt or harden to withstand temperatures below freezing, and many suffer injury at temperatures below 50°F (10°C). Subtropical plants can harden or acclimate (become accustomed to a new climate) to withstand freezing temperatures, and properly conditioned temperate plants can withstand temperatures substantially below freezing.
Recently planted, unestablished plants may be more susceptible to cold injury. One type of winter injury is plant desiccation or drying out. This is characterized by marginal or leaf tip burn in mild cases and totally brown leaves in severe cases. Desiccation occurs when dry winds and solar radiation result in the loss of more water from the leaves than can be absorbed and/or transported by a cold root system. Plant water needs should be checked after a freeze. Plants may have lost substantial moisture during a windy freeze. Plants will transpire (lose water vapor) on a sunny day after a freeze. Cold injured wood can be identified by lightly scraping the bark with your fingernail and examining the color of the cambium layer (food conducting tissue) just underneath. Green tissue indicates the plant is still alive at that point; black or brown coloration indicates dead or injured tissue. 
After a particularly harsh cold event, some plants may be very slow to recover, so some patience is required. “It will rise” with “the break of spring”. Branch tips may be damaged while older wood is free of injury. Delay pruning until new growth appears next spring to ensure that live wood is not removed. In the meantime, take Elsa’s advice and “let it go, let it go, let it go”. You may be “too relieved to grieve”. I hope I haven’t infringed on any copyrights by letting you know “It’s okay to put off the yard work in the name of plant physiology”.
Enjoy the holiday season!
For more information please see:
Treating Cold Damaged Plants
by Mary Salinas | Dec 16, 2014
This is the time of year when leaves are turning shades of yellow and red and falling from the trees. And this spurs homeowners to get out there with their rakes and rid them from their lawns. This is a good practice as too many leaves will shade out the grass and decrease the quality of the lawn come next spring. So, go ahead and rake them up. However, think about using as many as you can as mulch in other parts of your yard.
Leaves as mulch. Photo credit: Mary Derrick UF/IFAS Extension.
Leaves can be placed as mulch in landscape beds “as is” or chopped up with your mower or shredder into finer pieces and then spread around perennials, shrubs and trees. When chopped up or shredded, they tend to stay in place much better and don’t blow around when it gets windy. As the leaves break down over time, their nutrients are released and become available; that’s free fertilizer for your landscape plants. Leaves as mulch do have a natural look in the landscape, so if you prefer a more formal or polished look, you can spread a thin one-inch layer of a commercial mulch over the leaves.
Organic mulches (those made from plants) offer many benefits. They add organic matter and improve soil fertility as they decompose, thus reducing the need for added fertilizers. Mulch helps to maintain soil moisture so less frequent irrigation may be needed. Soil-borne disease can also be prevented as the soil does not splash up on the bottom leaves of plants during periods of rain. One of the favored reasons to use mulch is to prevent weeds in your landscape beds. And, of course, mulch is much prettier to look at than bare ground!
So how deep should you apply mulch? University of Florida experts advise a 3 to 4 inch layer of mulch around shrubs and trees. However, keep mulch from setting against the stems and trunks as that can cause moisture and pests to adversely affect them. Place just a thin one-inch layer of mulch over the rootballs of your plants.
Using leaves as mulch recycles a natural resource and saves you money, enriches your soil, fertilizes your plants and keeps them out of the local landfill.
For more information:
Landscape Mulches: What Are The Choices in Florida?
Mulch Recommendations
by Taylor Vandiver | Dec 16, 2014
Now that we’ve all been stuffed like a Thanksgiving turkey, it’s time to transition into the final and, arguably, most ornate holidays of the year. Right now you can hear your mantles and door frames crying out to be adorned. Your windows are begging for wreaths and giant red bows. And there may be a certain corner in your house that has been waiting all year for an evergreen, or two.
As we delve into the winter holidays our homes are being dressed to impress. There is nothing better than fresh foliage placed along a mantle or maybe a little mistletoe hanging from a previously unadorned beam. The scent of pine is in the air and I don’t know about you, but I’m ready to get decorating.
Here is a list of a few evergreen plants that make wonderful decorations for the season. You may even find some in your own backyard! Just make sure when you are removing foliage and fruit that you do it gently, so as not to harm the plant. Make all cuts at a 45 degree angle so that water will not pool on branch tips and rot. Also, if you forcefully remove foliage from a plant you could expose the susceptible cambium layer.
Wreaths and a decorated door frame add a bit of holiday cheer to this snowy scene. Photo courtesy Taylor Vandiver.
Traditional
Magnolia (Magnolia grandiflora) – This southern staple provides foliage that will liven up any banister or door frame. After being cut from the tree it can withstand the dryer temperatures indoors for days on end.
Hollies (Ilex spp.) – Hollies not only provide glossy green foliage, but bright red fruit that will beautifully adorn holiday arrangements and centerpieces.
Pine/Pinecones (Pinus spp.) – Pine trees offer a wispy presence to many decorations and their cones can give structure to wreaths and mantle pieces.
Boxwood (Buxus spp.) – Boxwoods are great for a touch of green.
Yaupon holly fruit and foliage. Photo courtesy UF/IFAS.
New Ideas
Abelia (Abelia x grandiflora) (evergreen to semi-evergreen) – Abelia are not commonly thought of when making holiday arrangements, but the texture of their foliage and the myriad of colors can spice up traditional decorations.
Aucuba (Aucuba japonica) – Aucuba offer a coarse texture that would pair well with the wispier pine foliage. Also, the gold dust variety will add a little more color to the mix.
Aspidistra (Aspidistra elatior) – Aspidistra foliage tends to feel more tropical. If you want to try a non-traditional arrangement these would work well and they can last for days provided a small amount of water.
Aspidistra foliage that could easily be worked into a stunning arrangement.
Remember that a few well placed planters can liven up even the smallest spaces. Try using a small evergreen tree or shrub such as a magnolia, cypress / false cypress or arborvitae and surround them with poinsettia or pansies. You can try a smaller planter and add in pine cones, poinsettia, grasses, etc. Also if you are celebrating this holiday season with a live Christmas tree, then don’t be afraid to ask the grower/retail center for discarded branches. These can easily be formed into a wreath or used throughout the house. And since this is Florida there’s always the option of decorating your palm tree!
by Julie McConnell | Dec 2, 2014
Over-pruning. Photo credit: JB McConnell, UF/IFAS
Many people picture sugar sand beaches, emerald green water, and gorgeous palm trees swaying in the breeze when they think about visiting or moving to Florida. The panhandle offers the beautiful Gulf of Mexico and sugar sand beaches, but sometimes its palms look a bit deficient. Why is that and what will it take to correct this? Although it seems counter-intuitive, major improvements can result from providing less attention to the palms by reducing the amount of pruning.
Over pruning palms leads to nutrient deficiencies and increases the likelihood of insect and disease problems. Pictured at left is an example of over pruned palms. This technique leaves the heads looking spindly and unattractive, and also hurts the palm’s short-term and long-term health. So, why do property owners send someone up a ladder to harm their palms? Most likely a combination of misinformation and routine.
Palms should have a 360 degree canopy, for example if the top of your palm tree is a clock (with hands, not digital!) you would not prune any fronds above 3 and 9 o’clock. The palms pictured above are pruned in a range from 11-1 o’clock and 10-2 o’clock.
Why does it matter how many fronds are on the palm?
- First off, palms are not trees as many people believe, but instead are grasses. Palms have just one growing point that is located at the top of the trunk, and this one bud called the apical meristem is busy making fronds that will not appear until several months from now.
- When nutrients are not available in the soil it can take 4-6 months for a deficiency to show up, so palm nutrition is tricky. Although they grow differently than trees and shrubs, one commonality is that they produce food through photosynthesis and need all available green tissue to make this happen.
- When there are fewer fronds, the palm has limited resources to create energy.
Native Florida soils are not able to meet the specific nutrition needs of most palms, so it is common to see nutrient deficiencies. Some nutrients such as nitrogen, potassium, and magnesium are mobile in the plant. This means that they can be moved to areas with sufficient amounts of the nutrient to other parts of the palm that do not have enough. This will cause some partial discoloration in leaves, which can be misinterpreted as a dying leaf when in reality it is just sharing food with the rest of the palm. If that frond has any green tissue remaining and is cut off, then a great source of nutrients has just been removed thus making the overall deficiency even worse!
What about “hurricane-cut” to improve wind resistance?
- Another common myth is that making a “hurricane cut” will reduce the likelihood of trees breaking in storms. Observations after the hurricane seasons of 2004 and 2005 along with research by scientists have shown that the opposite is actually true. Trees that had been given a “hurricane-cut” were more likely to have their crowns snapped than palms with full crowns.
- Damaged or dead fronds should be removed before storms to prevent them from becoming airborne during a storm, but green leaves should remain on palms.
So, how do you know the difference between normal shedding of fronds and a deficiency?
- Normal shedding (senescence) is indicated by an overall discoloration of the whole frond, not just sections, and the whole process of turning color and falling off (or hanging down depending on the palm) only takes a couple of days.
- A gradual shift to yellowing, browning, abnormal growth or other similar symptoms are typically nutrition related.
Above are some examples of common nutrient deficiencies found in Florida landscapes. These are examples of leaves that are still supporting the palm and should be left attached to the tree until the whole frond is brown.
For more information on proper pruning and nutrient deficiencies of palms, please see the publications indicated below.
Nutrient Deficiencies of Landscape and Field-Grown Palms in Florida
Pruning Palms
by Sheila Dunning | Dec 2, 2014
Camellias have been a part of the landscape in the Southeastern United States for over 200 years. They are native to Asia and were introduced near Charleston, South Carolina in 1786. The common name camellia refers to varieties and hybrids of Camellia japonica and to lesser known varieties of C. sasanqua and C. reticulata. The growing conditions in Northwest Florida are well suited for many camellia varieties. Camellias can serve several functions in the landscape including foundation plantings, screens, accent plants, background groupings and hedges. Maximum benefit can be achieved by mass plantings or groupings. Single plants should be focal point in beds rather than randomly placed throughout the lawn. Camellias flower in the fall and winter when their display of colorful blooms is most appreciated. During the remainder of the year their evergreen foliage, interesting shapes and textures, and relatively slow growth make camellias excellent landscape plants. Some camellia growers enjoy competing in flower shows and manipulate the flower buds to achieve larger and earlier flowers. This involves removing competing flower buds and applying gibberellic acid (a plant hormone). Individual cultivars can be selected for size and form ranging from small and irregular to large and upright. Texture and foliage color also differ among the various species and multiple varieties. Mid-season flowering varieties that bloom from November through January are best suited for Florida conditions.
Warm fall temperatures may prevent early varieties from flowering properly. Late-blooming selections may attempt to send out new leaves before the end of the flowering period which results in “bullnoses”. Bullnosing is characterized by poor quality flowers which do not open fully and may even drop while still tight buds. Extended dry periods while in the bud stage can make the condition more likely. While flowering, camellias need 1 inch of water applied each week. Camellias perform best in partially shaded locations which are enhanced by good drainage and air movement. Fertile, acidic soils high in organic matter are preferred. The soil must be well-drained because camellias will not grow in wet areas. Do not plant them in areas with a high water table and/or hard-pan. This will result in a shallow root system which is more susceptible to injury during dry periods. Camellias should be installed where cold air can move in and out freely, but the area should be protected from strong northwest winds. Plantings under established trees or in areas that has structures to block the wind are usually injured less by cold temperatures. These conditions enable the plants to gradually thaw or warm in the morning before being exposed to direct sunlight. Dense shade may result in sparse foliage and poor flowering. Camellias exposed to full sun may appear yellow-green, but may yield more flowers. Either situation is stressful to the plants and can lead to pest problems. Tea scale is the most common insect on camellias. Scales generally feed on the underside of leaves and may not be noticed until large populations have developed. Symptoms include very small elongated white and/or brown raised “flakes” on the underside of leaves that turn yellowish in color. Tea scale can be controlled with horticultural oil, sprayed after flowering finishes but while temperatures are sill cool, in late winter.
Cold Damage on Fruit Tree
