Green Roofs

Green Roofs

The Florida state wildflower, coreopsis, in bloom atop the Escambia County green roof. Photo credit: UF IFAS Extension

Most of us don’t think much about our roofs until there is a problem—a storm blows off shingles, causing a leak, necessitating a giant blue tarp to hold off the rain until we can get a contractor to replace the roof. But “a roof over your head” is one of those basic needs, perhaps only slightly less necessary for safety and survival than food and water.

Stormwater engineers and landscape architects have been thinking a lot about rooftops. Along with hard surfaces like roads and parking lots, roof area in a community is one of the biggest contributors of stormwater runoff. Those impervious surfaces don’t absorb any rainwater, contributing both to the volume and pollution potential of runoff from any given storm.

The skyline of downtown Kalamazoo, Michigan, as viewed from their City Hall green roof. Photo credit: Carrie Stevenson, UF IFAS Extension

While only applicable in specific situations, green roofs can provide a practical and beautiful solution to this problem. Escambia County has been home to the state’s largest green roof since 2009, housed atop the county’s Central Office Complex (COC). At over 33,000 square feet, it can absorb nearly 20,000 gallons of water during a rain, reducing flooding in a flood-prone area and allowing rain to soak into soil instead of becoming runoff. The COC roof was part of the building’s design from the beginning, but many commercial and government buildings have added green roofs as part of a retrofit. The rule of thumb is that if the building is sturdy enough to support an additional story, it can handle the weight of a green roof—including soil, vegetation, and water storage.

Last month, I visited the green roof atop Kalamazoo, Michigan’s City Hall. The imposing art deco building was constructed in the 1930’s, but the green roof on the building’s perimeter was added in 2011. Green roofs add tremendous environmental benefits but can be cost prohibitive, so many communities find grant funding (like the state of Florida’s Nonpoint Source Management grants) to help cover the expense. The Escambia County and Kalamazoo green roofs were both funded by grants. Besides the runoff reductions, a green roof can provide significant energy savings. Vegetation buffers a building from the incredibly hot summer rooftop temperatures, reducing the use of air conditioning and stabilizing indoor temperatures. This is the case for the Escambia County roof, in which an audit showed a 33% reduction in energy needs when compared to a conventionally designed building.

Green roofs can be built on flat-topped home roofs, and many European countries use them regularly. Plant selection for green roofs varies widely based on climate. Our local roof is mostly planted with beach dune species, while cooler, less humid regions make ample use of succulents like sedums. Low growing grasses and native wildflowers are great choices everywhere, providing color with limited maintenance.

Landscape  Q & A

Landscape Q & A

On August 12, 2021, our panel answered questions on a wide variety of landscape topics. Maybe you are asking the same questions, so read on!

Ideas on choosing plants

What are some perennials that can be planted this late in the summer but will still bloom through the cooler months into fall?

Duranta erecta ‘Sapphire Showers’ or ‘Gold Mound’, firespike, Senna bicapsularis, shrimp plant, lion’s ear

Where can native plants be obtained?

Dune sunflower, Helianthus debilis. Photo credit: Mary Salinas UF/IFAS Extension.

Gardening Solutions: Florida Native Plants  – see link to FANN: https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/native-plants.html

What are some evergreen groundcover options for our area?

Mondo grass, Japanese plum yew, shore juniper, ajuga, ferns such as autumn fern.

What are some ideas for partial morning sun butterfly attracting tall flowers to plant now?

Milkweed, salt and pepper plant, swamp sunflower, dune sunflower, ironweed, porterweed, and salt bush.

I’m interested in moving away from a monoculture lawn. What are some suggestions for alternatives?

Perennial peanut, powderpuff mimosa, and frogfruit.

We are new to Florida and have questions about everything in our landscape.

Florida-Friendly-Landscaping TM Program and FFL Web Apps: https://ffl.ifas.ufl.edu/

https://ffl.ifas.ufl.edu/resources/apps/

UF IFAS Gardening Solutions: https://gardeningsolutions.ifas.ufl.edu/

What are some of the top trends in landscaping today?

Houseplants, edible gardens, native plants, food forests, attracting wildlife, container gardening, and zoysiagrass lawns

Edibles

Artwork broccoli is a variety that produces small heads. Photo credit: Mary Salinas UF/IFAS Extension.

What vegetables are suitable for fall/winter gardening?

Cool Season Vegetables: https://gardeningsolutions.ifas.ufl.edu/plants/edibles/vegetables/cool-season-vegetables.html

North Florida Gardening Calendar: https://edis.ifas.ufl.edu/publication/EP451%20%20%20

Florida Vegetable Gardening Guide: https://edis.ifas.ufl.edu/publication/vh021

How can I add herbs to my landscape?

Herbs in the Florida Garden: https://gardeningsolutions.ifas.ufl.edu/plants/edibles/vegetables/herbs.html

My figs are green and hard. When do they ripen?

Why Won’t My Figs Ripen: https://www.lsuagcenter.com/profiles/rbogren/articles/page1597952870939

What is best soil for raised bed vegetable gardens?

Gardening in Raised Beds: https://edis.ifas.ufl.edu/publication/EP472

And there are always questions about weeds

How can I eradicate cogongrass?

Chamber bitter is a troublesome warm season weed in our region. Photo credit: Brantlee Spakes Richter, University of Florida, Bugwood.org

Cogongrass: https://edis.ifas.ufl.edu/publication/WG202

Is it okay to use cardboard for weed control?

The Cardboard Controversy: https://gardenprofessors.com/the-cardboard-controversy/

What is the best way to control weeds in grass and landscape beds?

Weed Management Guide for Florida Lawns: https://edis.ifas.ufl.edu/publication/EP141

Improving Weed Control in Landscape Planting Beds: https://edis.ifas.ufl.edu/pdf/EP/EP52300.pdf

Landscape practices

Can ground water be brackish and stunt plants?

Reclaimed Water Use in the Landscape: https://edis.ifas.ufl.edu/publication/ss545

How can I prevent erosion from rainwater runoff? 

Stormwater Runoff Control – NRCS: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/water/?cid=nrcs144p2_027171

Rain Gardens: https://gardeningsolutions.ifas.ufl.edu/design/types-of-gardens/rain-gardens.html

And https://gardeningsolutions.ifas.ufl.edu/pdf/articles/rain-garden-manual-hillsborough.pdf

What is the best time of the year to propagate flowering trees in zone 8B?

Landscape Plant Propagation Information Page – UF/IFAS Env. Hort: https://hort.ifas.ufl.edu/database/lppi/

Which type of mulch works best on slopes greater than 3 percent?

Landscape Mulches: How Quickly do they Settle?: https://edis.ifas.ufl.edu/publication/FR052

When should bulbs be fertilized?

Bulbs and More – UI Extension: https://web.extension.illinois.edu/bulbs/planting.cfm

Should I cut the spent blooms of agapanthus?

Agapanthus, extending the bloom time: https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/agapanthus.html

http://blogs.ifas.ufl.edu/wakullaco/2020/10/07/extending-bloom-time/

Plant questions

Monarch caterpillar munching on our native sandhill milkweed, Asclepias humistrata. Photo credit: Mary Salinas, UF IFAS Extension.

I planted native milkweed and have many monarch caterpillars. Should I protect them or leave them in nature?

It’s best to leave them in place. Featured Creatures: Monarch Butterfly: https://edis.ifas.ufl.edu/pdf/IN/IN780/IN780-Dxyup8sjiv.pdf

How does Vinca (periwinkle) do in direct sun? Will it make it through one of our panhandle summers? Can I plant in late August?

Periwinkles  and  No more fail with Cora series: https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/periwinkles.html#:~:text=Plant%20your%20periwinkles%20where%20they,rot%20if%20irrigated%20too%20frequently.

Insect and disease pests

What to do if you get termites in your raised bed?

The Facts About Termites and Mulch: https://edis.ifas.ufl.edu/publication/IN651

How to combat fungus?

Guidelines for ID and Management of Plant Disease Problems: https://edis.ifas.ufl.edu/publication/mg442

Are there preventative measures to prevent diseases when the humidity is very high and it is hot?

Fungi in Your Landscape by Maxine Hunter: http://blogs.ifas.ufl.edu/marionco/2020/01/16/fungi-in-your-landscape/

 

If you missed an episode, check out our playlist on YouTube https://www.youtube.com/watch?v=bp0HfdEkIQw&list=PLhgoAzWbtRXImdFE8Jdt0jsAOd-XldNCd

 

Soil Compaction in the Landscape

Soil Compaction in the Landscape

One big goal of establishing a home lawn and landscape is to enjoy an attractive setting for family and friends, while also helping manage healthy soils and plants.  Soil compaction at these sites can cause multiple problems for quality plants establishment and growth.  Soil is an incredibly important resource creating the foundation for plants and water absorption.

Photo courtesy: Stephen Greer, UF IFAS

Soils are composed of many different things, including minerals.  In Florida, these minerals often include sand of differing sizes and clay in the northern area of the counties in the panhandle of Florida. Soil is also composed of organic matter, nutrients, microorganisms and others.  When soil compacts, the air spaces between the sand or clay are compressed, reducing the space between the mineral particles.  This can occur anytime during the landscape and lawn construction phase or during long term maintenance of the area with equipment that could include tractors, mowers, and trucks.

What can be done to reduce soil compaction?  There are steps that can be taken to help reduce this serious situation.  Make a plan on how to best approach a given land area with the equipment needed to accomplish the landscape of your dreams.  Where should heavy equipment travel and how much impact they will have to the soils, trees, and other plants already existing and others to be planted?  At times heavy plywood may be needed to distribute the tire weight load over a larger area, reducing soil compaction by a tire directly on the soil.  Once the big equipment use is complete, look at ways to reduce the areas that were compacted.  Incorporating organic matter such as compost, pine bark, mulch, and others by tilling the soil and mixing it with the existing soil can help.  Anytime the soil provides improved air space, root will better grow and penetrate larger areas of the soil and plants will be healthier.

Even light foot traffic over the same area over and over will slowly compact soils.  Take a look at golf course at the end of cart paths or during a tournament with people walking over the same areas.  The grass is damaged from the leaves at the surface to the roots below.  Plugging these areas or possibly tilling and reestablishing these sites to reduce the compacted soils may be necessary.

Photo courtesy: Stephen Greer, UF IFAS

Water absorption is another area to plan for, as heavy rains do occur in Florida.  Having landscapes and lawns that are properly managed allow increased water infiltration into the soil is critically important.  Water runoff from the site is reduced or at least slowed to allow the nutrient from fertilizers used for the plant to have more time to be absorbed into the soil and taken up by the plants.  This reduces the opportunity for nitrogen, phosphorus, and other nutrients to enter water areas such as ponds, creeks, lagoons, rivers and bays.  Even if you are miles from an open water source, movement of water runoff can enter ditches and work their way to these open water areas, ultimately impacting drinking water, wildlife, and unwanted aquatic plant growth.

Plan ahead and talk with experts that can help with developing a plan.  Contact your local Extension office for assistance!

 

Water Quality Improves with a Chemical-Free Zone Along Your Shore

Water Quality Improves with a Chemical-Free Zone Along Your Shore

Our Gardening in the Panhandle blogs cover many horticultural topics concerning yards, however let us not forget about properties that contain a body of water (pond, lake, retention or detention basin, stream, river or Gulf of Mexico).  Out of the nine Florida-Friendly Landscaping™ principles, five directly deal with water quality.  Those principles are #2 Water Efficiently, #3 Fertilize Appropriately, #6 Manage Yard Pests Responsibly, #8 Prevent Stormwater Runoff, and #9 Protect the Waterfront.  An easy argument can be made that the remaining four principles (#1 Right Plant, Right Place, #4 Mulch, #5 Attract Wildlife, and #7 Recycle) can also impact water quality on your properties.

Pond 1

Photo Credit: University of Florida/IFAS Extension

The quickest and easiest way to start improving water quality is setting up a maintenance-free zone along your shore.  At minimum, you should keep all chemicals 10′ away from the water’s edge and increase that distance as your slope becomes steeper.  Chemicals include all fertilizers (#3) and any pesticides/herbicides (#6) meant for the landscape (there are times when situations arise where treatment of the water is warranted).  If you must fertilize up slope, make sure to reduce irrigation (#2) to about 25% of normal the first time which keeps the fertilizer from dissolving and running down your slope’s surface (#9).

Pond 2

Cascades Park in Tallahassee, FL.

If possible replace turfgrass with a no mow zone containing plants adapted for shorelines to prevent applications of fertilizer and chemicals.  Plants (#1) other than turfgrass will have deeper roots, stabilize the bank better and absorb more chemicals before entering the water.  These taller plants in turn can become habitats (#5) for birds and other specimens which can increase your ecosystem’s biodiversity.  Some properties have collection swales or low lying areas where water pools and then flows into the water.  It is best to understand how water flows through the property and reduce chemicals in those areas too (#8).

Organic Matter Decay

Heavy rains caused water levels to raise around this pond and decomposing leaf litter added a film over the pond.

As gardeners, we tend to compost our leaves and yard debris (#7) plus use mulch (#4) to reduce water loss from our soils.  Keep mulches and compost piles away from flood zones and when possible keep leaves from washing into your water as they can create films on the surface.  Never allow grass clippings to land on water surfaces as they will add nutrients when tissue decays.

As Florida continues to grow, we all must play an important role in keeping our water clean and safe for us, animals, birds, and aquatic life.  If you have questions on improving your water quality, please contact your local county Extension Agent or Water Regional Specialized Agent (RSA).  For additional information visit these other sites.

 

Protecting Florida’s Water Resources:  https://gardeningsolutions.ifas.ufl.edu/care/florida-friendly-landscapes/floridas-water-resources.html

Living on Water’s Edge:  http://www.sarasota.wateratlas.usf.edu/upload/documents/LivingontheWatersEdgeFreshwater.pdf

Urban Fertilizer Ordinances in the Context of Environmental Horticulture and Water Quality Extension Programs:  Frequently Asked Questions:  https://edis.ifas.ufl.edu/publication/AE534

 

 

 

 

Tough Plants for Tough Weather

Tough Plants for Tough Weather

Stoke’s aster ‘Mel’s Blue’ 20 days after Hurricane Sally’s landfall. Notice how soil was washed away from root ball, all the leaves emerged post-hurricane. Photo credit: Mary Salinas, UF/IFAS Extension.

Hurricanes can wreak havoc in your landscape, but they can also reveal what plants are the toughest and most resilient. It’s a great learning opportunity.

A few weeks ago, Hurricane Sally came along and brought about 10 feet of surge and waves across my landscape and completely covered everything except the tallest trees for about 18 hours. (Fortunately, our house is on stilts and we did not have intrusion into our main living areas.)

As expected, the trees, including Dahoon Holly and Sweetbay Magnolia, took a beating but stayed intact. With their dense fibrous root system, most of the clumping native grasses also stayed put.

Perennial milkweed 3 weeks post-hurricane. New topsoil and compost now covers the rootball. Photo credit: Mary Salinas, UF/IFAS Extension.

The most surprising plant species that survived were about a dozen Stoke’s aster and 3 perennial milkweed.  4-5 inches of soil all around them was washed away, most of the roots were exposed, and the leaves were stripped or dead. The other perennials that had lived nearby were all washed away. To my surprise, within about 10 days after the storm, these two plant species started poking up new stems and leaves.

Here’s a list of some of the plants either in my yard or in the neighborhood that survived Hurricane Sally’s storm surge and may be suitable to add to your coastal landscape:

  • Dahoon holly, Ilex cassine
  • Muhly grass, Muhlenbergia capillaris
  • Dwarf Fakahatchee grass, Tripsacum floridanum
  • Perennial milkweed, Asclepias perennis
  • Stoke’s aster, Stokesia laevis, specifically the cultivars ‘Mel’s Blue’ and ‘Divinity’
  • Bottlebrush, Callistemon citrinus
  • Gardenia, Gardenia jasminoides
  • Bougainvillea, Bougainvillea spp.
  • Flax Lily, Dianella tasmanica
  • Crapemyrtle, Lagerstroemia spp.
  • Cabbage palm, Sabal palmetto
  • Canary Island date palm, Phoenix canariensis
  • Sweetbay magnolia, Magnolia virginiana
  • Augustinegrass, Stenotaphrum secundatum
  • And, unfortunately, the rhizomes of the invasive torpedograss also survived.

For more information on salt tolerant and hurricane resistant plants, see:

UF/IFAS Gardening Solutions: Coastal Landscapes

UF/IFAS Gardening Solutions: Salt-tolerant Lawngrasses

UF/IFAS Gardening Solutions: Trees That Can Withstand Hurricanes

 

Summer Irrigation Tips

July’s hot summer weather has given way to August’s 31 days of what will likely be temperatures and humidity equally elevated and intense. Wishes for November’s cooler thermometer reading are already creeping into daily conversations. The lawns and gardens in Wakulla County have rains as a mitigating factor to counteract the wilting potential of normal to excessive temperature readings. Unfortunately the arrival of water from above is not on a set or easily predictable schedule.

Traditionally, summer is the wettest season in Florida, with more than half of the annual rainfall occurring during the June to September “wet season”. Florida’s highest average annual rainfall occurs in the Panhandle with averages exceeding 60 inches per year. The Pensacola and Tallahassee weather stations are listed among the ten “wettest” stations in the nation. Still, this pattern of seasonal precipitation can vary greatly between locations, years and even days.  This variability often results in the need to water the lawn, landscape and garden. By following a few guidelines, you can produce the best results for plants under stress and conserve a vital and limited resource.

It is most efficient to apply water between 5:00 a.m. and 10:00 a.m. for several reasons. Only water that is in contact with roots can be absorbed by the plant. If water is applied after 10:00 a.m., a substantial portion of it will evaporate before it reaches the roots; more will then need to be applied and this resource’s productivity will be reduced. Never water late in the afternoon as evaporation will still be a problem, and wet turf and plants will invite a variety of fungal diseases to flourish as night settles.

Photo Courtesy: Les Harrison, UF/IFAS Wakulla County Extension

In the case of landscapes and gardens, water should be applied only when the moisture in the root zone system has been depleted to an unacceptable level, usually by 1/2 to 2/3 of the stored soil-water. There are several ways to determine when the soil-water reservoir has been depleted beyond an acceptable level.  The simplest method is a visual inspection of the turf or plants. Common symptoms of water stress include leaf color changes to a bluish-gray tint, footprints which linger long after being pressed into the grass and curled or folded leaf blades. Be sure the sprinklers are delivering water to the target area as water which misses the soil and is applied to hard surfaces such as driveways and sidewalks will be wasted. It also may pose an environmental problem in the form of runoff.  Surface runoff that flows past the landscape will usually reach streams, ponds, or the Gulf of Mexico. If it picks up pollutants along the way, they too will reach the surface water bodies. 

Over watering can be just as damaging as too little water. Excessive irrigation water can infiltrate the ground and reach groundwater aquifers. This issue is complicated when groundwater runs close to the surface. Excessive nutrients or pollutants can be discharged into surface bodies or move vertically into the deeper land layers.  The connected springs and sinkholes in Wakulla County make the movement of surface water a common concern.  Responsible and efficient irrigation will have positive effects far beyond the front yard.

To learn more about the effective use of water in Wakulla County’s landscapes, contact your UF/IFAS Wakulla Extension Office at 850-926-3931 or http://wakulla.ifas.ufl.edu/