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.


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.

Secrets & Shortcuts of the Florida Gardener November 7, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 11:55 pm
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My grandfather once told me that a garden is a testing ground for patience. Not until I had a yard of my own – and a job, bills, household chores, and more – did his words make sense. After hours of bug bites, broken nails, and dirt-stained knees (and more than a little profanity), I decided there had to be an easier way.

If you want your yard to look like a botanical garden, you might consider cashing in your 401K to hire a small live-in landscaping crew. On the other hand, if you’re willing to accept a few weeds, some extra shoot growth, and the occasional pest, you’re well on your way to becoming a successful Florida Gardener. So what is the motto of the Florida gardener? Perfection is overrated.

Albert Einstein identified 3 rules of work that can be applied to gardening in Florida: “Out of clutter find simplicity; From discord find harmony; In the middle of difficulty lies opportunity.”

A good landscape design (not shown here) can reduce a lot of unnecessary frustrations.

Out of clutter find simplicity – Humans like instant gratification, but a true Florida gardener is a master of tolerance and endurance. And if a landscape design is done right, the results can be very pleasing.

The key to remember, regardless of what anyone says, is that size matters. Mature plants take up a lot more room in the landscape than when they’re first planted, so give them room to grow. This means fewer plants you have to buy (money savings) and fewer planting holes you have to dig (sweat savings).

Another key element to simplifying your landscape is hydrozoning, the art of designing your landscape by water use: xeric (low), mesic (medium), and oasis (high). Keep high water use areas to a minimum (e.g. turf areas), and utilize as many drought tolerant native and Florida-friendly plants as possible. Group plants with similar water needs together in the landscape to minimize water waste. By putting the right plant in the right place, you save yourself a lot of heartache down the road.

From discord find harmony – One of the most common statements I hear from clients is, “I can’t grow anything I used to be able to grow up North!” Rather than get frustrated trying to train your tulips and daffodils to get a suntan, choose plants that have characteristics better suited to Florida’s environment.

Slow growing plants need less pruning. They maintain a neat appearance, without looking obsessively manicured (remember your 401K…). Additionally, by choosing wide spreading plants, you have to buy fewer plants to fill in a given space. Drought tolerant plants require less water once established, so you’ll spend less time dragging the hose around or trying to adjust your sprinkler system. Just as important, but often overlooked, is the need to choose plants that are pest and disease resistant. Part of being a successful Florida gardener is minimizing your inputs and contributions to the environment in the form of pesticides. Fewer pests mean fewer chemicals.

In the middle of difficulty lies opportunity – Einstein’s final rule is probably the most uplifting; it causes you to find the silver lining in your garden (and I don’t mean the slug and snail trails crisscrossing the sidewalk and driveway). All gardeners face limitations, but every one of these obstacles can be overcome with a little patience (there’s that word again) and ingenuity. 

Create self-mulching areas under trees that shed leaves so you don’t have to rake them up.

Mulching is a necessary activity in the landscape to help retain moisture, regulate soil temperature, reduce erosion, and minimize weeds. One potential opportunity is in the availability of free and low-cost mulch from local tree trimmers and municipalities. Some counties sell shredded, composted yard debris to residents for a minimal cost, reducing the need to haul bags and bags of mulch from garden centers. If you have trees that shed leaves and pine needles, collect those and spread them around your yard as mulch or create self-mulching areas underneath tree canopies.

Fertilizing doesn’t have to be a chore, if it’s done right. First ask yourself why you’re applying fertilizer in the first place. Is it because your plants and lawn need a boost of nutrients, or because your neighbors are hauling out their fertilizer spreaders and giving you dirty looks? Remember to use slow-release fertilizer and only apply when needed – to correct a nutrient deficiency, to encourage shoot growth, or to encourage extra blooms.

Weeding is the most dreaded task of any gardener, but the key is timing. Learn to identify the weeds that show up and claim squatters’ rights in your landscape. By understanding their life cycles, you can pull them before they go to seed, reducing the chance of return visitors. Maintain a 2- to 3-inch layer of mulch in landscaped beds to help reduce weed seed germination. Finally, learn to tolerate a few weeds; remember the Florida gardener’s motto…

Less than 1% of all bugs are bad. Let the good ones, like this spider, do the work for you.

There are many pest resistant plants, but there is no such thing as a pest-free yard. Less than 1% of all bugs in the landscape are pests; the rest are either beneficial or harmless. With that in mind, consider manual removal of pests before dragging out the big guns – pesticides. Many pests can be removed by hand or with tweezers, if you’re squeamish. A strong spray of water from the hose will also knock off most creepy crawlers. The laziest (but just as effective) method of all is to simply prune off the infested leaves or branches and throw them away.

Keep in mind that working in the yard doesn’t have to be work, if you have the right attitude and the right tricks. I hope these tips will help you to avoid the embarrassing moments of being caught by your neighbors while you scream at your plants, curse the bugs, and faint over your water bill. But if you still need a little reassurance or someone to vent to, contact your local County Extension Office (http://solutionsforyourlife.com). I guarantee, they’ll understand.


An Introduction to Aquascaping October 24, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 11:55 pm
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Florida may be surrounded by saltwater, but there are thousands of freshwater systems (both natural and created) in the form of lakes, ponds, and wetlands scattered across the state.  These seemingly insignificant water bodies play a rather significant role in our state’s environmental issues. They provide flood protection, water purification, and fish and wildlife habitat. In residential neighborhoods, they can even increase property values by added aesthetic appeal.

There is a large disparity in the design of many man-made freshwater systems. The majority will have some type of turfgrass growing all along the banks, right down to the water’s edge. This is common because it’s easy to maintain and properly managed turfgrass acts as a filter for pollutants, reduces erosion, and allows a view across the water. Yet, there are other options.

Aquascaping is the planting of aquatic and wetland plants to enhance or restore the function of a freshwater system, whether natural or man-made. Although this process is only an imitation of nature, the benefits are tremendous.

The key is to identify the slope of the shoreline and choose plants according to their tolerance of water depth. There are four identified planting zones in a freshwater shoreline, although there may be fewer depending on the actual design of the individual water body. If you have the opportunity to design and build a small pond on your own property, consider one that is irregular in shape, since it will have a greater shoreline area and offer more wildlife habitat than a round or rectangular pond.

The deep zone has a water level that ranges between 90 cm and 150 cm deep. Many plants suitable for this zone may be completely submerged year round. Examples include spatterdock and water lilies. The mid zone ranges 15 cm to 90 cm deep and may include plants like arrowhead, maidencane, pickerel weed, and soft-stem bulrush. The shallow zone can have standing water as deep as 15 cm, or can have exposed up to 15 cm above the water level. Many plants for this zone must tolerate periods of complete exposure and partial submergence. Examples include sand cordgrass and blue flag iris. The shallowest zone is known as the transition zone and remains exposed all year, with soil ranging 15 cm to 45 cm above the water level. Salt grass and cordgrass are examples of plants tolerant of this zone.

Because Florida has an abundance of native and exotic, non-invasive aquatic plants, it is not at all difficult to beautify the shoreline of a pond or small lake. Utilize a variety of plants that will look natural, add color, texture, and fragrance to the landscape, provide better defense against invasive species, and offer food and shelter to wildlife. Avoid exotic plants that are invasive or have invasive potential. The University of Florida’s IFAS Assessment of Florida’s Non-Native Plants (http://plants.ifas.ufl.edu/assessment/) offers recommendations about plants based on the north, central, and south regions of the state. The IFAS Center for Aquatic and Invasive Plants (http://plants.ifas.ufl.edu) also provides lots of useful information to get you started.

The final consideration with aquascaping is maintenance. As with any garden or landscaped area, maintenance is necessary to keep away weeds and unwanted invasive plants. Hand-pulling unwanted plants is the best option to maintaining around your pond, although a few chemical herbicides are available for homeowners to purchase in retail garden or hardware stores. If you choose to use herbicides, read all labels carefully. Make sure that the product is labeled for use in or near water bodies, follow all instructions for use, and wear the proper protective gear.

For more information about aquascaping and other Florida-friendly landscaping practices, contact your local county Cooperative Extension office or visit http://FloridaYards.org.


Fertilizing the Landscape August 26, 2010

Filed under: Uncategorized — Hillsborough County Residential Horticulture @ 8:11 pm
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Just like humans, plants need nutrients for overall health. Nutrients like nitrogen, phosphorus, potassium, calcium, zinc, magnesium, and iron can be provided to plants in many ways, not just out the bottom of a fertilizer spreader. Products like compost or even grass clippings can provide nutrients in small amounts, reducing the fertilizer needs of a lawn or landscape over time.

Obviously, plants grow in the wild without assistance from humans, so the real purpose of applying fertilizer to a landscape is to satisfy some human need – to see more flowers, to increase fruit production, or to enhance a plant’s appearance. While those are acceptable reasons, it is important to make sure that the application of fertilizer does not exceed the plants’ needs or capacity to utilize the nutrients provided.

As with anything in life, there are consequences to excessive behaviors. Over-fertilizing may cause problems for the growth, appearance, and health of the lawn and other plants. Additionally, excess fertilizer can leach through the sandy soils typical of most of the state, contaminating groundwater supplies. Use caution when fertilizing near water bodies by leaving a 10- to 20-foot buffer zone to the water’s edge where no fertilizer is applied. This will reduce unnecessary runoff of excess fertilizer and the potential for polluting the water body itself.

There’s a lot of confusion when it comes to choosing the right fertilizer and knowing when, how often, and how much to apply. The goal of this article is to address some of the most common questions related to fertilizing lawn and landscape plants.

Q.  What is a fertilizer analysis?

A.  A fertilizer analysis represents the percentage of the three major nutrients found in the bag of fertilizer – nitrogen (N), phosphorus (P2O5), and potassium (K2O). Since most of Florida’s soil is high in phosphorus, it is recommended that the middle number of the analysis be zero, or as low as possible. Adding excess phosphorus to the landscape may result in leaching and runoff.

Q.  What is a “slow or controlled-release fertilizer”?

A.  This type of fertilizer contains a plant nutrient (usually nitrogen (N)) in a form that makes it available to the plant for a longer period of time than a typical quick-release (water-soluble) product. Additionally, less of that nutrient leaches into the soil from rain or irrigation, reducing the chance of groundwater pollution.

Q.  Under what conditions should the landscape be fertilized?

A.  There is no simple answer to this question. If aesthetics are not an issue or plants are established or in the process of fruiting, then fertilization may not be required. However, if plants exhibit certain nutrient deficiencies, are newly planted, or if the homeowner desires more or faster growth, then fertilization may be justified.

Q.  Should fertilizer be added to the hole at the time of planting?

A.  Adding fertilizer at planting has never been associated with improved or reduced survival. Application of slow release fertilizer is not likely to hurt the plant, provided it is applied according to the directions on the product. However, adding soluble fertilizer to a newly installed plant could burn roots if too much is applied. A safer recommendation would be to till the soil at the planting site (and the area around it) with an organic compost or soil amendment before planting.

Q.  How much fertilizer should be applied to the lawn/landscape?

A.  Fertilizer is applied according to pounds of nitrogen per 1,000 square feet of bed or lawn area. The phosphorus content of the fertilizer should be 0 to 2% P2O5, and the ratio of nitrogen (N) to potassium (K2O) should be 1:1 or 2:1. Slow-release fertilizers should be applied at no more than 1 pound of actual nitrogen per 1,000 square feet per application. Water-soluble fertilizers should be applied at no more than ½ pound of actual nitrogen per 1,000 square feet per application.

The table below indicates the recommended amounts for established landscape plants, depending on the desired level of maintenance.

Table 1. Amounts of Nitrogen Fertilizer vs. the Level of Maintenance for Landscape Plants

Level of Maintenance Amount of Nitrogen Fertilizer
Basic 0 – 2 pounds N/1000 ft2/year
Moderate 2 – 4 pounds N/1000 ft2/year
High 4 – 6 pounds N/1000 ft2/year

Source: Trenholm, L.E.; Gilman, E.F.; Knox, G.W.; & Black, R.J. 2002. Fertilization and Irrigation Needs for Florida Lawns and Landscapes (ENH860). Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

For lawn areas, the fertilization guidelines are determined by the type of grass as well as the desired maintenance level.

Table 2. Fertilization Guidelines for Established Turfgrass Lawns

Species/Location Nitrogen Recommendations (lbs/1000 ft2/yr)
Bahiagrass – North

Bahiagrass – Central

Bahiagrass – South

2 – 3

2 – 4

2 – 4

Bermudagrass – North

Bermudagrass – Central

Bermudagrass – South

3 – 5

4 – 6

5 – 7

Centipedegrass – North

Centipedegrass – Central

Centipedegrass – South

1 – 2

2 – 3

2 – 3

St. Augustinegrass – North

St. Augustinegrass – Central

St. Augustinegrass – South

2 – 4

2 – 5

4 – 6

Zoysiagrass – North

Zoysiagrass – Central

Zoysiagrass – South

3 – 5

3 – 6

4 – 6

Source: Trenholm, L.E.; Gilman, E.F.; Knox, G.W.; & Black, R.J. 2002. Fertilization and Irrigation Needs for Florida Lawns and Landscapes (ENH860). Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

Q.  What is the best way to spread fertilizer?

A.  The ultimate goal is to broadcast the fertilizer uniformly over the desired areas of the landscape. A properly calibrated drop spreader is the best tool for lawn areas, but may not efficiently reach all areas of landscaped beds. Keep in mind that if tree and shrub fertilization zones overlap with lawn fertilization zones, those areas should be fertilized for one or the other of the plant types – not both. Remember to apply no more than about ¼ inch of water to properly get the fertilizer into the root zone.

Q. Can palms be fertilized the same way as other landscape plants?

A.  Palms have different nutritional requirements than other plants in the landscape. If the palms are the primary concern, landscaped areas within 30 feet of large established palms should be fertilized with a 4-1-6-2 Mg (N – P2O5 – K2O – Mg) ratio fertilizer. The nitrogen, potassium, and magnesium should have equal percentages of each nutrient in slow-release form. Once this 30-foot area around the palm is fertilized, do not apply a separate fertilizer to any lawn or landscape plants found there.

Fertilizer, when applied properly to the landscape, can provide much needed nutrients to improve the appearance, growth, flowering, and fruiting of plants. It is important for homeowners to understand the nutrient need of their lawns and landscape plants, as well as their desired level of maintenance.

For more information on proper fertilization in your area, contact your local county Extension office (http://solutionsforyourlife.com/map/), a part of the University of Florida’s Institute of Food and Agricultural Sciences (IFAS).


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