Gardens of Water: The Basics
C O A S T A L
N E W S
S T A T E
N E W S
Gardens of Water
nc state university NORTH CAROLINA COOPERATIVE EXTENSION Summer 2009
Water gardens can be designed to fit
almost any landscape, no matter how
large or small. When choosing the
location of a pond or pool, consider placing it so
that it can be appreciated through a window from
the house or as a focal point in the landscape.
There are several ways to create a water
garden. The most popular is using a plastic liner,
which comes in PVC (polyvinyl chloride), butyl
rubber or polyethylene materials. These liners are
chemically inert and safe for fish and plants. They
come in various thicknesses, from 20 – 45 mils,
and generally last anywhere from 10 – 20 years.
The liner will be the most costly item, with the
price based on the size of your water garden and
liner type. Fountains and waterfalls add beauty
and a focal point to a water garden. Place the fo-cal
structure where it will have the most impact.
A pool can be stocked with four types of
plants: deep-water plants, bog plants (mar-ginals),
oxygenators, and floating plants. A
mix of these plant types ensures a thriving,
self-sustaining system. Cover 60 – 70% of the
pond surface with floating plants, such as water
hyacinth, and/or container plants with floating
foliage, such as water lilies. Place 1 or 2 bunches
of submerged or oxygenating plants per square
yard of pond surface area. Many aquatic plants
are very aggressive and should be planted in
containers to prevent spreading and overcrowd-ing.
Fill the containers with heavy garden soil,
and avoid chemicals or fertilizers that can harm
aquatic life. Pack the soil tightly in the container
and 1 – 2 inches from the container rim. Cover
the remaining depth with pea gravel to keep the
soil from floating up, and place the container at
the correct depth in the pond. Plants should be
introduced to the pond during the growing sea-son.
In newly constructed pools, place the plants
several weeks before introducing fish.
You must wait 24 – 48 hours before stocking
the pool with fish and aquatic plants so any chlo-rine
can evaporate. If your water is treated with
chloramine or chlorine dioxide, use counteractive
chemicals from a water-garden supplier. Various
brands are available; many add enzymes, aloe and
other ingredients to help keep fish healthy dur-ing
their transition. Combining fish and aquatic
plants creates an ecological balance in the pond.
In addition to a filter system, fish and aquatic
plants should counteract any algae growth that
occurs after construction. It can take anywhere
from 6 – 8 weeks to establish a balance.
As with any garden, maintenance is neces-sary
to keep a water garden thriving. Maintain
filters, remove debris, and keep fish and plants
healthy. For more information, visit http://www.
in this issue
JC Raulston Arboretum
JC Raulston Arboretum
JC Raulston Arboretum
Sustainable Gardening — Summer lawn fertilization
Plants, Pests and Pathogens
Televised live the second Tuesday of each month and featuring horticultural agents and specialists from NC State University and the NC Cooperative Extension Service, Plants, Pests and Pathogens is your opportunity to stay up to date on the latest horticultural problems and plant recommendations from a variety of NC experts. Plants, Pests and Pathogens is televised live at many Extension offices across the state on the second Tuesday of May, June, July and August, from 10 am to Noon. To find out when and where you can participate, contact your local Extension center.
Clematis, Ascochyta blight
(Photo courtesy Janna Beckerman, NCSU Image Library of Plant Problems)
Food Production — Blossom-end rot
Now that spring has sprung and warm-season grasses — such as bermuda, centipede, zoysia and St. Augustine — are flourishing, it is time to begin fertilizer applications. Each type of warm-season grass needs different nutrients, with some needing more than others. It is best to obtain a soil sample before making applications. Soil testing is more accurate than guessing. It eliminates the guesswork and the possibility of applying too much or too little of any key nutrient. If you have not taken a soil test, follow the guidelines below for your specific grass.
For a bermudagrass lawn, after green-up apply 1 pound of nitrogen per 1,000 square feet, every 4 to 6 weeks, from March through August. Examples of a complete fertilizer to use are 12-4-8 or 16-4-8. A little math is needed to determine exactly how much fertilizer to apply to meet the 1 pound of nitrogen per 1,000 square feet. Fertilizer is made up of a ratio of nitrogen, phosphorus and potassium. The first number represents the percent weight of the bag that is nitrogen, the second number phosphorus, and the third number potassium. To determine the amount of nitrogen needed, divide the first number by 100. So if you were using 12-4-8, you would need to apply 8.3 pounds per 1,000 square feet.
For a centipedegrass lawn, do not apply any fertilizer until mid-June. Centipedegrass lawns need ½-pound of nitrogen per 1,000 square feet of a high potassium fertilizer such as 5-5-15, 6-6-12 or 8-8-24. Typically only one application is needed per year, with exceptions to the coastal areas that may need another application in August to enhance performance. To determine the amount needed per 1,000 square feet, just divide the first number by 50.
For a St. Augustinegrass lawn, apply ½-pound of nitrogen per 1,000 square feet using the same fertilizer recommended for bermuda. Make the ½-pound N application in May, June and August, but apply 1 pound of nitrogen per 1,000 square feet in July.
For a zoysiagrass lawn, apply ½-pound of nitrogen per 1,000 square feet 3 weeks after spring green-up, using the same fertilizer recommended for bermuda. Make another application in late June or early July, and again in mid-August.
Tomatoes, squash and cucumbers are summer favorites for eastern NC gardeners. They tolerate our warm weather, are easy to grow and have the potential to generate a lot of fruit from a single plant. This makes them ideal vegetable crops for home gardeners with a small amount of space. However, all of these crops have the potential of developing a disorder called blossom-end rot.
Blossom-end rot is triggered by a lack of calcium in the cell tissue at the blossom end of the fruit. This leads to a breakdown of the cell tissue, followed by secondary fungal infections. The secondary infections are easily managed by simply picking off the infected fruit, but how do we stop the initial onset of the end rot? Controlling calcium is the key. Calcium flows into plant tissues with water that is drawn up by roots from the soil. If this process is disrupted, the flow of calcium stops. Your answer to blossom-end rot? Keep the calcium flowing.
To manage blossom-end rot, maintain the soil pH at 6.0 – 6.5 with proper lime applications (as indicated by soil test results) and through consistent, deep watering. Maintaining soil pH in the 6.0 – 6.5 range ensures there will be adequate calcium available for roots to absorb.
Deep watering also helps maintain a consistent flow of water from the roots to the new growth. Shallow watering results in plants setting roots too close to the soil surface, which quickly dries out. Applying ½-inch of water two or three times each week encourages plants to set roots deeper in the soil where water volume and soil temperatures are cooler and more consistent.
More detailed information on blossom-end rot in fruiting crops like tomatoes, squash and cucumber can be found online:
Summer squash: http://hgic.clemson.edu
(Photo courtesy Joe Zobkiw, NCSU Image Library of Plant Problems) Regional News of the Coastal Plain
• During dry weather, water
deeply rather than frequently to
promote deeper, more drought-resistant
• Removing the old flowers from
many annuals and perennials
will promote the production of
new blossoms throughout the
• A 2- to 3-inch layer of pinestraw
or bark mulch will help reduce
weeds and conserve soil mois-ture
in landscape beds.
• Scout vegetables and fruits
regularly for problems. Have
problems identified by your
local Extension agent, and get
recommendations for control as
soon as a problem begins.
• Most vegetables and fruits
require regular watering and
fertilization through the sum-mer
to keep producing. Many
herbs, on the other hand, are
very drought tolerant and their
flavor diminishes with excess
water and nutrients.
• Harvest vegetables regularly to
keep up production.
• Mulch vegetables and fruits with
straw, old leaves or aged bark
to help control weeds and hold
moisture in the soil.
• Mowing regularly and at the
correct height will promote
dense turf and help reduce weed
problems. Centipede, bermuda,
and zoysia grasses should be
mowed at a height of 1-inch,
while St. Augustine should be
mowed at 3 inches.
• Leave clippings on your lawn
– they return nutrients and
moisture to the soil and do not
contribute to thatch buildup.
Environmental Stewardship — Reducing inputs
Garden Spot — New Hanover County Arboretum
Can we reduce our reliance on fertilizer, water
and pesticides in 2009? Of course we can.
Let’s take a look at how we can reduce the need
for all three in our own backyards through good
Regarding fertilizer, maybe — just maybe
— we tend to overdo that in the first place,
particularly on mature trees and shrubs. Un-necessary
fertilization with nitrogen can increase
disease problems and reduce drought hardiness.
Landscape plants that have low fertilizer needs
include common coastal natives such as Eastern
redcedar, live oak, yaupon holly, American beau-tyberry,
devilwood osmanthus, blanket flower
and wax myrtle.
Sandy soils are not only low in fertility,
they’re also extremely dry. So the coastal plants
cited above are also good choices for low water
use. Other drought-sturdy natives (or near na-tives)
include Shumard oak, nutall oak, Ameri-can
holly, southern magnolia, longleaf pine
and hickories. Rosemary comes to mind as an
excellent drought-tolerant (and low-fertility)
herb. Crapemyrtle, ginkgo, camellias, Chinese
fringetree and Chinese pistache are tough non-natives
to consider for low-input landscapes.
Strategic plant selection is also critical in
reducing insect and disease problems in the
landscape, which reduces the need for pesticide
applications. Some plants are known to have
chronic pest problems, and we should limit our
use of these plants in the landscape. In addi-tion,
we should also strive for a greater overall
diversity of plant selection, which will support
a more robust beneficial insect population as
well as reduce the risk of pest epidemics. When
homeowners and landscapers overuse a limited
palette of plants, problems tend to crop up over
time. Instead, our landscapes should be made up
of a wide array of plant species because mon-oculture
and overuse lead to problems.
New Hanover County Coop-erative
Extension started their
efforts to develop the Arboretum
Gardens in 1985, on the grounds
of what had once been Bradley
Creek Elementary School. Now
(24 years later) the gardens offer
enthusiasts a chance to learn in a
beautiful and relaxing garden set-ting.
From the beginning, Master
Gardeners have been a vital part of
the planning, designing, construct-ing,
planting and maintaining of
the Arboretum, located at 6206
Oleander Drive in Wilmington. Open
during daylight hours, the gardens
are free to the public and feature
a large water garden that houses
a wonderful collection of water
lilies; a Japanese tea house nes-tled
in the Japanese Garden; a
bountiful vegetable garden where
you can collect ideas for your own
backyard; a ‘Try a Tool’ shed which
features tools and devices that make
gardening less stressful; as well as many
other theme gardens that showcase good plants
for southeastern North Carolina. The gardens
are always changing, and
new demonstration trials
are planted seasonally. Life
today moves at a fast pace.
Make plans to stop and smell
the roses at the New Hanover
County Arboretum and take home
some ideas for your garden. Learn more
— David Barkley
The Arboretum at New Hanover County
includes a children’s garden and
a large water garden. (Photos
courtesy JC Raulston Arboretum)
Showstopper — Knock-Out Red Rose
For years disease-resistant roses have been on the market only to disappoint Southern gardeners. Well, look no further because the Knock-Out® Red Rose (Rosa hybrida ‘Radrazz’ – PP #11836) has the grit to withstand our hot, humid Carolina weather.
This exciting rose cultivar is a shrub rose that grows about 3 feet tall and wide. As the weather warms, 3-inch diameter cherry-red blooms appear as terminal clusters of single flowers. As long as the plants continue to grow through spring, summer and fall, this rose will continue to flower. Like nearly all roses, Knock-Out® Red Rose performs best in full sun with fertile, well-drained soil. Prune during the growing season on an “as-needed” basis to control plant size. Water during periods of drought to maintain a continual supply of flowers.
Chosen in 2000 as an All-America Rose Award winner, this 2009 Showstopper Plant is truly a knock-out !
Extension Gardener provides timely, research-based horticultural information. We publish 4 issues per year. Send comments about Extension Gardener to
Editor and Team Leader
Lucy Bradley, Ph.D., Extension Specialist, Urban Horticulture
Box 7609, NC State University
Raleigh, NC 27695-7609
Managing Editor Will Strader
Content Editor David Goforth
Coastal Plain Anne Edwards,
Piedmont Carl Matyac, Mark Blevins
Mountains Donna Teasley,
Production Editor Barbara Scott
Designer Karl Larson
The use of brand names does not imply endorsement by N.C. Cooperative Extension nor discrimination against similar products or services not mentioned.
Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
©North Carolina Cooperative Extension
Extension Gardener may not be reproduced without written permission. Any news media using sections of the newsletter should credit “Extension Gardener, N.C. Cooperative Extension.”
Straw-bale gardening saves space but requires more attention to watering and nutrients than traditional gardening. Vegetables that grow well in bales include lettuce, tomatoes, cucumbers, squash and eggplants. Condition straw bales 10 days before planting. Place each bale at its growing location in full sun and on edge to keep the string from touching soil. Soak the entire bale for 3 days by slowly watering it. Over the next 5 days, add a high nitrogen fertilizer (such as 33-0-0) at 1 tablespoon per day and slowly wash it in. On day 9, add a complete fertilizer (17-17-17, 10-10-10 or 19-19-19) and water again. Plant on day 10 and water again. One bale can hold 2 tomato plants, 6 cucumbers or 2 to 3 squash. A soaker hose will save time. Wilting indicates the need for watering.
Around the State
Pest Alert — Downy mildew
In late summer agents start to receive samples of downy mildew on muskmelon and cucumbers. This disease can cause a lot of damage quickly. Cucumber and muskmelon are the cucurbits most susceptible to downy mildew, but it may also attack melons, squash, pumpkins, gourds, and other members of the Cucurbitaceae family.
Symptoms first appear as small, angular, yellow lesions on the upper side of the leaf. A white to purplish mildew may be observed on the lower side of the leaf during humid weather. As the lesions expand, their centers turn brown. Often the margins of the diseased leaves curl upward. During favorable weather leaf lesions coalesce, killing large areas of the leaf surface. This results in a stunting of the plant and a failure of the fruit to mature properly. Even fruit
Downy mildew on a cucumber leaf (Photo courtesy ©G.C. Holmes, NCSU)that reach maturity may have an off-flavor. In severe cases, the entire plant will die.
The fungus requires extended periods of wet weather and leaf wetness for the infection. Several cucumber varieties are resistant to downy mildew, but watermelon and muskmelon varieties are not. Control of downy mildew depends on cultural practices, early detection and timely applications of fungicides. Early detection is essential for the proper control of foliar pathogens. If weather conditions become favorable for the development of downy mildew, begin protective fungicide applications and continue on a 4- to 7-day interval. Look for fungicides containing the active ingredients mancozeb or chlorothalonil.
JC Raulston Arboretum
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