Hillsborough Extension Garden Blog

Solutions you can use for your gardening problems.

Raised Bed Gardening December 26, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 11:55 pm
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The life of a plant can be a difficult one. From the time it germinates from a seed or is propagated from a cutting, a plant is expected to delight, amaze and even inspire its human caretakers. And if it fails or ceases to draw an occasional gasp or smile of appreciation? Another eager plant is waiting nearby to take its place.

Too often, the reason a plant does not perform to our satisfaction has nothing to do with the plant itself and everything to do with us and the surrounding environment. But unfortunately, the plant pays the ultimate price.

It is difficult to meet a Florida gardener who has never complained about the poor quality soils we encounter in this state. Yes, believe it or not, sand is a type of soil. But in dealing with poor soils in our landscapes, we must address drainage issues, nematodes and other pests, nutrient availability, soil pH levels, weeds, erosion… The list goes on and on.

Rather than continue to fight with the existing soil at ground level, consider an alternative: raised bed gardening. There are several benefits to gardening in raised beds. For one, you have better control over the quality of the soil in which to plant. Soil borne problems like nematodes can be controlled more easily. Access to plants for pruning, harvesting and weeding is easier because the plants are above ground level. Finally, raised beds, if designed as such, can serve as decorative hardscapes in your yard.

The first and most important consideration when building a raised bed is the material used. Avoid treated wood, since there may be a risk of chemicals leaching into the soil and nearby plants. Many types of construction materials, including bricks, stones and plastic, may be used. Your choice of material will depend on your style and budget.

When considering a location for your raised bed, look for a level spot that receives at least 4 to 6 hours of sunlight. Using a hose or string, lay out the approximate size and shape of the bed. Don’t make it too big; you will need to reach the plants in the middle of the bed as well as along the edge. If building multiple beds near each other, be sure to leave enough space in-between so that you can walk and work around them. Use a pervious material like gravel or mulch to line the walkways between and around the raised beds. If you build a shallow bed (6 inches or less), consider lining the bottom and edges with weed cloth to keep grass and weeds from creeping into the bed.

A raised bed should drain well because soil that remains very wet will deprive plant roots of oxygen. This is especially true for vegetable beds. The best type of soil for your ornamental raised bed is sandy clay loam soil mixed with organic matter like peat moss, finished compost, sawdust or ground bark. For vegetables, the best mix is one-third topsoil, one-third peat moss, and one-third sand or perlite. When you add soil to your raised bed, be sure to grade the soil so that it slopes towards the edge of the bed, rather than the center.

Choosing plants for your raised bed garden is essentially the same as with a regular garden bed. However, if the raised bed is very shallow – 4 to 6 inches deep – you may be limited to planting annuals, vegetables and some herbs. The deeper the bed, the more plant options you have.

As always, the Florida-friendly landscaping™ principle of choosing the right plant for the right place holds true. For each garden bed, choose plants that have similar needs regarding sunlight, water, nutrients, soil pH and drainage. Also be sure that the mature size of the plants chosen is suitable for the location in the landscape. Woody perennials and shrubs should be placed at the rear or the center of the bed, depending on its position in the landscape, while annuals and groundcovers should be easy to reach for maintenance and replacement.

Once your raised bed is constructed and plants are installed, mulch the surface 2 to 3 inches deep to help regulate soil temperature, reduce water evaporation from the soil, control erosion and reduce weeds. Water the bed when needed, and check the soil in-between watering. If the top inch or two is still wet, there is no need to irrigate.

If designed, built and maintained correctly, a raised bed garden offers a host of benefits and options to any gardener. By choosing the right plants for your raised bed, you will be pleasantly surprised at how well they perform. For more information on building a raised bed garden, visit the Texas A&M Extension publication online at http://aggie-horticulture.tamu.edu/publications/guides/E-560_raised_bed_garden.pdf.


Botanical Symbols of the Season – Part IV December 21, 2010

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Mistletoe (Phoradendron serotinum)

Most people associate mistletoe with kissing during the holiday season for anyone caught standing under a sprig of this plant (often strategically placed in a doorway). Before Christianity, however, the Druids believed mistletoe could cure diseases, increase the fertility of humans and animals, offer protection from witches and bring good luck. They believed it was a holy plant because it rooted closer to heaven than any other plant. If two Druid enemies met beneath a tree on which mistletoe was growing, they would lay down their weapons, exchange greetings, and observe a truce until the following day!

These traditions and beliefs of peace and harmony were adapted by the English and French, giving us the holiday custom of kissing under mistletoe bunches. While hanging mistletoe is a Christmas tradition in the United States, it is more commonly associated with New Year’s Eve in Europe.

In the home landscape, mistletoe is a parasite and not planted voluntarily. Mistletoe’s distinctive green leaves, stems, and white berries–each with a sticky seed inside–are easily recognizable. As a small seedling, it roots into the bark and wood of a tree and makes a connection with the growing ring of the host. Although mistletoe makes its own food, it steals water and nutrients from its host tree. Mistletoe will parasitize many hosts in Florida, in particular elms and laurel oaks. A botanical anomaly, it is the only complete plant considered a true parasite since it often kills the hardwood tree it infests.

With Christmas and other celebrations right around the corner, take some time to ponder the history, the lore and the symbolism of the plants around you. It just might help you be less stressed about the season and instead be more captivated by the wonder of it all!


Botanical Symbols of the Season – Part III December 17, 2010

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Clover (Trifolium repens L.)

In Irish tradition, St. Patrick used the shamrock or three-leaf clover as a symbol to teach about the Holy Trinity: one leaf for the Father, one for the Son and one for the Holy Spirit. Supposedly, when a shamrock is found with the fourth leaf, it represents God’s grace. It was white clover (Trifolium repens L.) that was used during this time. Another story claims that during a sermon, St. Patrick asked the crowd how many leaves the clover had. When they replied it has three but can also be one, St. Patrick’s response was that it is also that way with God (the Father, Son and the Holy Ghost). Since this story was written more than one thousand years after the time of St. Patrick, however, it is often considered a legend.

In Florida, white clover is not widely used in residential landscapes, because it is a cool-season legume and acts like an annual plant. It is commonly used in pasture applications because of its high protein content and digestibility for cows, compared to grass alone. If you like the looks of the characteristic trifoliate leaf, however, consider oxalis for the home landscape. This shamrock substitute is found in many nurseries and garden centers as either an annual or perennial.

Commonly known as wood sorrel or false shamrock, Oxalis triangularis subspecies papilionacea, is endemic to Brazil and can be grown outdoors from zones 8 – 11. Prolonged days over 85 degrees will cause this plant to look “tired” but once the daytime temperatures drop a bit, the show is spectacular! The leaves are a deep purple-red color with light pink to white flowers that create a wonderful contrast.


Windy Freeze Predicted Tonight — What to do? December 15, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 1:35 am
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Radiational freezes or frosts occur on calm, clear nights when heat radiates from the surfaces of objects into the environment.  When the air is moist, a radiant freeze results in frost on surfaces.  Dry radiational freezes leaves no frost but can cause freeze damage.

Windy cold, like what’s predicted for tonight, results in an advective freeze. Advective freezes occur when cold air masses move from northern regions causing a sudden drop in temperature.  Due to the rapid drop in temperature and prolonged duration, plant protection during advective freezes is often more difficult.

Coverings protect more from frost than from extreme cold. During freezes with windy weather, the covers tend to be less effective because the wind blows the heat away. During windy freezes or very cold nights, the addition of plastic sheeting over the cloth may be worth the effort on valuable plants.

Covers that extend to the ground and are not in contact with plant foliage can lessen cold injury by reducing radiant heat loss from the plant and the ground.

Foliage in contact with the cover is often injured because of heat transfer from the foliage to the colder cover. Some examples of coverings are cloth sheets, quilts, or black plastic.


  • Move container plants inside or under protective covering like a lanai. Group containers together to increase their protection.
  • Use windbreaks like fences, walls, tree canopies or other coverings to protect container plants that can’t come inside. Coverings include frost cloth, sheets and quilts, plastic, and even large cardboard boxes (these work great).
  • A string of Christmas lights or a light bulb placed under a protective cloth may be enough to provide simple protection to ornamental plants.
  • Most perennials are root hardy. Use mulch to protect the roots, and be accepting of foliage that dies back to the ground.


Agricultural operations use sprinkling for cold protection, which helps keep leaf surface temperatures near 32°F (0°C) because sprinkling utilizes latent heat released when water changes from a liquid to a solid state. Sprinkling must begin as freezing temperatures are reached and continue until thawing is completed. Water must be evenly distributed and supplied in ample quantity to maintain a film of liquid water on the foliage surfaces. Based on weather reports, that means running the sprinkler system tonight from 2 am to 8 am. WE DO NOT RECOMMEND THIS OPTION for home landscapes! Residential landscape sprinkler systems do not have the needed flow to protect plants in this manner. As a result, cold damage to plants from inadequate amounts of irrigation water may be more severe than if nothing was done at all.

Instead, prepare your landscape by moving plants to a protected area and covering with protective cloths before the sun goes down this evening. Then snuggle up on the couch with a cup of hot cocoa.


Freezing temperatures predicted again, so whatever you do tonight, you’ll probably have to do again tomorrow.

Remove plastic covers when the sun comes out and the temperatures rise above freezing or provide ventilation of trapped solar radiation. This will prevent your plants from “baking.”

By Wednesday, remove the protective coverings and check plants to make sure they have enough water. Wind causes evaporative loss, so plants may be suffering from both cold stress AND water loss. Do not overwater, though. Use your finger to check the moisture of the soil.

There is debate about pruning after a hard freeze:

  • OPTION 1 – Wait until freeze risk has passed (about February 15th), check plants for living tissue, then prune back to remove dead/dying tissue. The damaged plant material helps to insulate and protect the still living parts of the plants.
  • OPTION 2 – Prune all dead and freeze damaged tissue back immediately after a freeze. This will make plants easier to cover and protect if freezing temperatures return before the end of the season.

Demonstration Gardens on a Tankful December 12, 2010

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With the holidays and the cooler weather come a lot of extras that might be hard on our pockets this year… especially travel. If you’re one of many Floridians opting to stay put this season, consider a cost-effective alternative: visiting one or several local public demonstration gardens in your neck of the woods.

The University of Florida Cooperative Extension Service is responsible for educating the public with research-based information that helps to improve quality of life and offer solutions to everyday problems. One of the best ways to answer gardening and landscaping questions, therefore, is to showcase plants, in the form of gardens.

There are 61 public demonstration gardens scattered across the state. Many of them are located on the grounds of the Extension Office in a particular county, but many are featured in front of public buildings such as libraries. They vary greatly in size, shape, and plant choices, but they all promote the same concepts – choosing the right plant for the right place; planning for stormwater runoff and reduction of non-point source pollution; and being Florida-friendly!

And the best part? They’re all free to visit! The only cost will be a couple of gallons of gas… not bad for a day of entertainment!

While I would love to expound on the amazing features of each of the 61 gardens, I chose to highlight five particular gardens, partly because of their geographic location and partly because of what they have to offer. For a list of all 61 gardens, their locations and contact information, visit the University of Florida’s EDIS publication, Demonstration Gardens in the University of Florida Cooperative Extension Service, at http://edis.ifas.ufl.edu/EP108.

Panhandle – Escambia County

The Escambia County Demonstration Garden was established in 1995 by a dedicated group of Master Gardener volunteers.  Since then, 11 demonstration areas have been created to help educate the community about plants that grow on the Gulf Coast and research-based horticulture practices.  Each year, Master Gardeners offer two garden festivals which are free to the public and feature talks and a plant sale. The gardens are located behind the Extension office at 3740 Stefani Road, Cantonment, FL 32533-7792.

For more information, visit: http://escambia.ifas.ufl.edu/hort/demo-garden.shtml

Northeast Florida – Nassau County

Established September 2005, the purpose of the Nassau County Demonstration Garden is to show examples of Best Management Practices (BMPs) for Northeast Florida landscapes, adopted from the University of Florida’s Florida Yards & Neighborhoods program. The garden provides an opportunity for Nassau County residents, children and businesses to see the care and maintenance of landscape plants best suited for the area. These principles include: using low-volume irrigation, choosing the right plant for the right place, mulching, recycling, attracting wildlife, and integrated pest management (IPM).

The gardens are located at the Nassau County Cooperative Extension – Yulee Satellite Office, 96135 Nassau Place Road (Nassau County Governmental Complex). For more information, visit: http://nassau.ifas.ufl.edu/horticulture/demogarden/factsheet.html

Central Florida – Lake County

The Lake County Extension Discovery Gardens are located at the Lake County Agriculture Center, 1951 Woodlea Road, Tavares, Florida 32778-4262. It is situated on a 3.5 acre site made up of 20 major themed gardens, each designed to show a different gardening aspect in Central Florida. It has more than 700 different plants demonstrating landscapes that are attractive, functional, and friendly to the environment. All plants are labeled, and cultural information is available upon request at the Master Gardener Plant Clinic in the main building.

For more information, visit: http://discoverygardens.ifas.ufl.edu/tour_our_gardens.htm

Tampa Bay area/West Coast – Pinellas County

Covering approximately 160 acres, the Pinellas County Florida Botanical Gardens is the largest public demonstration garden as part of the University of Florida’s Extension demonstration garden collection in the state. Over 150 types of bird, mammals, and reptiles have been documented on site. Several endangered or threatened species including Bald Eagles, Gopher tortoises and Sherman Fox squirrels make their home here. There are also a number of threatened or endangered plants found on site.

The Florida Botanical Gardens are an educational and leisure resource and a model of conservation and sustainable practices by integrating education into the exhibits and programs, applying the principles of green architecture, utilizing energy-and water-efficient Florida-friendly techniques, and focusing on local condition, native plants and appropriate non-native, non-invasive ornamentals. Find them at 12520 Ulmerton Road, Largo, FL 33774.

For more information, visit: http://www.flbg.org

South Florida – Indian River Research and Education Center

At the University of Florida’s Indian River Research and Education Center, located at 2199 South Rock Road, Fort Pierce, FL 34945-3138, visit the Teaching Gardens and the Linear Garden for a great south Florida landscaping experience.

In 1997, a new University of Florida teaching program was established at the Indian River Research and Education Center. Increased student enrollment and the need for hands-on laboratory activities outdoors inspired the idea of transforming a piece of fallow land into a Teaching Garden. The north half of the garden was developed as a subtropical fruit demonstration block displaying 88 specimens of mango, lychee, avocado, citrus and other tropical fruit. The south half of the garden was designed as an ornamental display garden. The garden is intended to serve as an outdoor teaching laboratory available to many classes offered at IRREC. It also serves as an ideal location for variety trial testing, master gardener training, as well as leisurely visits from the general public.

The Linear Garden may be only three feet wide, but it is 2,426 feet long (nearly half a mile) and is therefore affectionately called the ‘Linear Garden’.  It spans the entire length of South Rock Road and is located on the East side of the street across from the IRREC facility and USDA. The garden includes approximately 247 different species of trees, palms, shrubs, ground covers and vines.  The garden was designed to showcase specimen plants and display other common landscape plants utilized in the South-Central Florida region with attention to foliage type, color and size in addition to flowering times and color providing year-round interest regardless of the season.

For more information on both gardens, visit: http://irrecenvhort.ifas.ufl.edu/virtualgarden/details.htm


Botanical Symbols of the Season – Part II December 10, 2010

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Passionflower (Passiflora spp.)

In the home landscape, Passiflora species are important nectar sources for bees, butterflies and hummingbirds. They also serve as larval host plants for many butterfly species, especially longwing butterflies. The zebra longwing, the state butterfly of Florida, prefers yellow passionflower (P. lutea), two-flowered passionflower (P. biflora) and corky-stemmed passionflower (P. suberosa). The gulf fritillary butterfly feeds on yellow passionflower, stinking passionflower (P. foetida) and maypop (P. incarnata).

Passionflower vines are great climbing plants and will use their tendrils to hold onto anything with which they come in contact. Arbors and trellises are perfect supports for these wonderful vines. In south Florida, these plants bloom on and off all year long. In central and north Florida, passionflower vines will bloom in the warmer months, but a cold winter might cause some dieback.

Contrary to popular belief, the “passion” in passionflower does not refer to love and sexuality, but rather to the passion of Christ. In the 15th and 16th centuries, Spanish Christian missionaries capitalized on the unique physical structures of this plant to teach about the last days of Jesus Christ, and the crucifixion in particular. The pointed tips of the leaves represent the Holy Lance, and the coiling tendrils symbolize the whips used in the flagellation of Christ.

The flower bears ten petals and sepals, which represent the ten faithful apostles (remember, Peter denied Christ and Judas betrayed Him). There are also radial filaments on the flower, which represent the crown of thorns. The ovary of this plant is chalice-shaped and thus represents the Holy Grail. Finally, the 3 stigmas symbolize the 3 nails used, and the 5 anthers symbolize the 5 stigmata (4 wounds from the nails and 1 from the lance).


Botanical Symbols of the Season – Part I December 6, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 5:11 pm
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December is a month filled with a diversity of cultural and religious celebrations, but Christmas, in particular, is a holiday strongly associated with plants. Much botanical symbolism has existed in other cultures, long before the advent of Christianity, and was carried over into the Christian faith as teaching tools or as religious symbols. Today, many of these plants are chosen just because of how well they perform in a home landscape, but sometimes it’s interesting to know a little bit more about them, from a historical perspective. Over the next few weeks, I’ll try to feature several plants that have relevance to the spirit of the season.

Holly (Ilex spp.)

Probably the most common plant that comes to mind this time of year is the holly. A holly plant is eye-catching all year round but particularly in the middle of winter when many other plants have lost their leaves. There are more than 500 cultivated Ilex varieties in the United States and several native to Florida.

During holiday celebrations, hollies are used as wreaths and decorative plants, their bright green leaves and stunning red berries clearly representative of the good will and bright cheer associated with Christmas. Long before the celebration of Christmas, however, Celtic Druids believed that the evergreen nature of the holly helped to keep the earth beautiful when deciduous trees shed their leaves.

In Pagan religions, placing holly leaves and branches around the outside of one’s home during winter was considered a sociable and welcoming gesture to invited guests. Ancient Romans used holly to decorate their houses and temples for Saturnalia, the mid-winter feast (December 12th) in honor of the sun god Saturn. Holly was also exchanged as a symbol of kindness and friendship.

During the time the Romans celebrated Saturn, Christians celebrated the birth of Jesus Christ. Those early Christians adopted the tradition of decorating their home with holly, and it eventually lost its pagan association and became a symbol of Christmas.

The pointed leaves of the holly symbolize the crown of thorns Jesus wore at His crucifixion, the berries symbolize the blood of Christ, the white flowers represent the purity and birth of Jesus and the bitter bark represents the passion of Christ.


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