Plant Preview

Welcome to Plant Preview, a blog dedicated to helping gardeners learn about gardening techniques and preview new plant cultivars. Read about new plants here first and hear how your "comrades in compost" are making use of new plant introductions in their gardens and landscapes. Blog author Geri Laufer is a life-long dirt gardener, degreed horticulturist, author and former County Extension Agent. Plant Preview is copyrighted by Geri Laufer.

Friday, June 25, 2010

A Riot of Summer Flowers

     This time of year my front Cottage Garden is a riot of color. The house faces south, and while this garden gets some shade in the early morning (when these photos were taken), it is primarily full sun. Because our home is so symmetrical with the twin gables, twin windows and shutters, twin window boxes and arched front door echoing the eyebrow window, I have taken special care to add elements of asymmetry like the Lady Banks Rose climbing up only one side of the front porch arch. The stone walk is 8-feet wide between the driveway and the front door but half that width going around to the left toward the Shade Garden. The 'Emerald' Zoysia lawn is like a plush green carpet and withstands the summer heat without irrigation, but in the photos it is dappled with sunlight.
     The color continues year-round, although late June is pretty much a highlight. Now the many Daylilies are blooming in shades from white to pink, purple, red, yellow and orange. Purple Coneflowers, Shasta Daisies and Black-eyed Susans provide a daisy flower shape to contrast with the trumpet shapes of the daylilies. Dark pink Coleus, black Sweet Potato Vine and silvery Lamb's Ears add durable foliage color, while spikey variegated Yucca and sword leaves of Siberian, Japanese and Roof Irises contrast with the horizontal lines of Creeping Thyme. Pink Crinum lilies are blooming with characteristic abandon, and clouds of blue-green leaves on white Baptisia remain as it produces its interesting ballooning seed pods.

     Some of the spring annuals like Love-in-a-Mist (Nigella) or Peony Poppies have seed pods filled with ripened seeds, some of which I am collecting to sow in January and to give to friends. I've been growing and saving seeds of my Gardening Grandmother's Feverfew (Brides Buttons) since 1981. Sometimes Zinnia or Annual Rudbeckia or even Ironweed seeds themselves between the cracks of the stone paving and if it doesn't obstruct traffic too badly I allow it to flower there. 
The Hydrangeas were briefly wonderful this year due to the early rains, but after 15 days straight of higher-than-90 degree F. temperatures and no rainfall the tender flowers have taken a beating. The leaves wilt every afternoon but then come back every morning ready for new solar abuse. They would perfer a little afternoon shade, but I envisioned a bank of powder blue against the ochre bricks when I designed the front border, so they are planted here. Wavy snakes of Foxgloves are filled with ripening seed. In my garden-before-last the Foxgloves actually did reseed, but not so in my last garden. Wonder if they'll germinate in place in this garden? Lavender Garden Phlox reinforces the color of the Purple Coneflowers. 
Lamb's Ears are blooming and its flowers around the periphery of the clump do not interfere with the pool of silver provided by the leaves. Showing only green for now are the fragrant Spearmint, Mexican Tarregon (Tagetes) and the late brilliant yellow Chrysanthemums that will bloom from Thanksgiving to late December or early January, when they are finally cut down by a hard frost. These are corseted in perennial hoops economically made from tomato cages cut in half (horizontally) using the super-giant red bolt cutters my Dad gave me so long ago. The exhuberent growth in this garden conceals their aluminium stays, as well as crowding out weeds.
     I heard a statistic that 80% of garden flowers do well in full sun, while 20% of them do better in shade, so I am grateful for the wide pallet of colorful flowers.

Sunday, June 20, 2010

Father's Day

     Father’s Day is a special day to celebrate our fathers. In 2010 the third Sunday in June marks the 100th anniversary of the holiday. Thanks and a tip of the hat to the Dads, Step-dads, Grand-dads, Uncles, Cousins, Big Brothers and men who have had an influence in our lives.
     A website with everything you ever wanted to know about Father’s Day can be found at and there’s a historical list of the Top TV Dads from Huffington Post at
Thanks, Dad!

Photo credit: Rat Race Escape Artists website

Friday, June 18, 2010

Cresting or Fasciation - One of Nature's Conceits

There are some really odd flowers growing in my garden. Instead of the usual round daisy shape of a Black-eyed Susan, they look flattened, crested or ribbon-like. See for yourself. 

The word for these fascinating distortions of the plant world is "fasciation", from the Latin 'fascia' = "to fuse".  

What causes plants to produce fasciated flowers? Mostly science doesn’t know. Some causes of Fasciation include bacterial infection, insect or mite attack, severe pruning, wounding or mechanical damage, chemical damage or experimental applications of plant hormones, or mutations in rapidly dividing cells at the growth tip. However, most appear by chance with no obvious cause.

Humans seem to be fascinated by fasciated plants, and the literature documents fasciation in more than 100 different varieties. Their unusual shapes make them prized by many, like the Fantail Willow that is essential in the world of flower arrangers. According to Dr. T. Ombrello of the UCC Biology Department additional examples are Crested Cockscomb Celosias (which I have propagated by seed) and beefsteak tomatoes. Dr. Ombrello says, “If you have ever wondered why beefsteak tomatoes have such unusual shapes, look at their flowers and you will readily see why”.  Many of the ones perpetuated by vegetative propagation  become cultivars within species.

How about sending in photos of the fasciated plants you come across? We'd love to see them. 

Tuesday, June 15, 2010

Top 10 Tips when Gardening with Children

1. Serene adults with their own enjoyment of the garden provide roles models for the child to imitate. Remember, gardening is caught, not taught!

2. Plan ahead to maximize success. Site the garden in full sun near a water source, and enrich the soil with compost.

3. Easy Does It. Try a small garden plot for starters, 2 x 4 feet or 3 x 3 feet.

4. Quick results are best for short attention spans. For example, try radishes instead of asparagus.

5. Little children tire easily. Let the adults provide the support for the child and do the weeding, but let the kids pick the cukes.

6. The small size of the child calls for appropriately scaled, child - sized tools, providing teaching opportunities for pride of ownership and proper care of tools. Be aware of good quality.

7. Individual adult attention, one-on-one, is a reinforcer in and of itself.

8. External recognition such as a blue ribbon in the Children’s Class of a juried Flower Show, a small cash prize at the Youth Division of the County Fair, or simply a printed certificate at the neighborhood Show & Tell, will be replaced later by pride and self satisfaction.

9. Use the child’s harvest, for example, after the strawberry plants start yielding, take a strawberry shortcake to school for a class treat, or pick some flowers to take to a shut in.

10. Claim your own rewards: renewal of a child-like joy and sense of wonder

Ferry Morse seed packets for children.

Saturday, June 12, 2010

Summertime Heat Tolerance

Plant Hardiness and Heat Tolerance

It’s summertime and the livin’ is easy; fish are jumpin’ and although the cotton is not yet high, the weeks of 90-degree temperatures are upon us. This got me to thinking about how plants get heat-stressed and the entire concept of heat-tolerance ratings. However, since the gardening public is more familiar with the idea of cold hardiness, I’m going to start with that.

Cold Hardiness
Plant hardiness is a complex phenomenon and depends on many variable qualities of individual plants (not of their projected sites). The Royal Horticulture Society (RHS) Shorter Dictionary of Gardening points out some natural adaptations to cold temperatures include deciduous or herbaceous habit, procumbent growth, thicker bark, seed dormancy or accelerated life cycle, among others.

Cold hardiness is a characteristic attributed to plants that are capable of withstanding the rigors of winter without greenhouse protection. Often abbreviated as “hardiness”, the general population sometimes uses the term loosely to mean a general toughness or ability to survive, but that’s not strictly the case. The actual story is really interesting!

Hardiness Zones

Back in 1960 the U.S. Department of Agriculture (USDA), in cooperation with the American Horticulture Society (AHS), produced an ingenious map based on annual minimum temperatures. Isotherms, contour lines connecting points of equal temperature on a map, were developed using data from 124,500 weather stations and analyzed by the Meteorological Evaluation Services, Inc., in Amityville, NY and labeled Hardiness Zones. Brilliant! They extrapolated variable characteristics of hardy plants to Zones on a map, thus producing an approximation; a guide or rule of thumb; shorthand, as it were, to enable people to get an idea of where plants will make it through the winter.

I am too young (!) to remember a time before Hardiness Zones were in common usage in the horticultural world, but this was a real breakthrough. This precious map was widely publicized, often printed on the inside covers of gardening reference books and was/is used extensively. In 1990 the map was revised to include Canada, Mexico, and Hawaii, and later zone maps were also produced by others for Europe, South Africa, Australia, New Zealand, Japan and China. But keep in mind, theses zones are simply an approximate indication of the coldest temperature band in which the plant will survive. Thus, most gardeners are familiar with the concept of plant hardiness.

Heat Tolerance
However, cold isn't the only factor determining whether plants will survive in the garden. At 86 degrees F. (30 degrees C.) plants begin to experience physiological damage, and with the advent of weeks of 90 degree Farenheit temperatures in Atlanta I really wanted to look at the concept of heat tolerance in plants.

As part of the 75th anniversary celebration of the AHS (1997), a Heat-Zone Map was published, based on the number of days each year that the daily high temperatures reach or exceed 86 degrees. The data used to create the map was gathered and again analyzed by the Meteorological Evaluation Services, Inc. This map has 12 zones which overlap but unfortunately do not follow the hardiness zones exactly, so when using both maps to make selections, two zones are indicated for plant. Each of the 12 zones of the Heat Tolerance Map indicate the average number of days each year that a given region experiences "heat days"-- temperatures over 86 degrees (30 degrees Celsius)-- at the point when plants begin to decline due to the heat. The zones range from Zone 1 (less than one heat day) to Zone 12 (more than 210 heat days). The use of Hardy or Half-Hardy Tropicals (what we used to think of as “houseplants”) in the garden provides an entire category of plants that laugh at heat waves, and it seems to me that this trend became popular after the advent of the Heat Tolerance data.

Plants vary in their ability to withstand heat, not only from species to species but even among individual plants of the same species! Unusual seasons-fewer or more hot days than normal-will invariably affect results in the garden. And even more than with the hardiness zones, gardeners find that many plants will survive outside their designated heat zone because of complications by many factors such as microclimates, rainfall, hot winds or cloud cover.

On the AHS website, H. Marc Cathey, AHS President Emeritus, points out, “The effects of heat damage are more subtle than those of extreme cold, which will kill a plant instantly. Heat damage can first appear in many different parts of the plant: Flower buds may wither, leaves may droop or become more attractive to insects, chlorophyll may disappear so that leaves appear white or brown, or roots may cease growing. Plant death from heat is slow and lingering. The plant may survive in a stunted or chlorotic state for several years. When desiccation reaches a high enough level, the enzymes that control growth are deactivated and the plant dies.”

So the AHS Plant Heat-Zone Map is used the same way that the Hardiness Map is used, but unlike the Hardiness Zone Map, this map is highly proprietary. “The AHS Heat-Zone map is a copyrighted document that is wholly owned by the American Horticultural Society. Any reference to, reproduction of, or attempt to code plants using the map's information without written consent by AHS is a violation of the copyright. Durable full-color posters of the AHS Heat-Zone Map are available for $9.95 each. To order check the website or call (800) 777-7931 ext. 119.”

I think because the Heat Tolerance Map is not open source, this resource is less widely used, which I think is shortsighted; too bad. What do you think? Do you bother with the heat tolerance zones when choosing plants for your gardens?

Photo credits: Thermometer-Ohio State Engineering, Hardiness Zone Map-Missouri Extension, Tropical containers-author photo.

Monday, June 7, 2010

Top 10 Tips for Watering the Garden & Landscape

Watering the Garden
Since plants are 90 – 95% water they can quickly wilt if they get too dry. Good gardeners monitor the water available to their plants (rain) and avoid this stressful wilting with extra irrigation. Some plants (thinking Hydrangeas here) wilt every day on hot afternoons but come back by evening. Others (Rosemary) are less tolerant and quickly turn yellow when water stressed.

But too much water isn’t good either. Plants require a balance of both water and oxygen around their roots. Overwatering excludes the necessary oxygen from the soil causing roots to rot and die and resulting in yellow or wilted tops. On the other hand, too little water does not allow the roots to replace water lost by the plant through transpiration from its leaf surfaces. In this case, tender roots shrivel and die, and again we get wilting. In both cases, either too much or too little water, the plant suffers from lack of moisture in its tissues.

I have long been uncomfortably amused by the dark concept of “PWP”. The Permanent Wilting Point is a technical term for “bye, bye baby”, the point of no return when the plant is DEAD.

So I’ve assembled my Top 10 Tips for Watering the Garden and Landscape Plantings.

1. How often to water depends on how often it rains. As a rule of thumb, most plants thrive with about an inch of water a week. Visualize a short, 10-minute downpour every two or three days. Keeping the soil lightly moist prevents it from drying out completely. It’s the fluctuation that is damaging to most plants.

2. How often to water also depends on the soil type. Clay soils hold water a long time, while sandy soils are like a sieve, letting the water quickly drain away below the root zone. Both types of soil can be improved with the addition of organic matter. Organic matter adds lightness and air to clay soils; it acts as “tiny sponges” holding the water in sandy soils.

3. The very best time to water is in the cool of the morning, when the wind is calmed, evaporative water loss is minimal and the rising sun quickly dries off the leaves.

4. Water the soil, not the leaves. When water sits on plant foliage for hours (e.g. overnight), fungus spores can germinate and attack leaves, buds, flowers, and fruit. Plants susceptible to leaf spots, fruit rots, and flower blights are best watered in the morning, when the warming sun will quickly evaporates the water and discourage fungus development. Avoid watering disease-susceptible plants in the evening.

5. Wind and air movement increase water loss from the pores (stomata) on the leaf surfaces, called transpiration. That’s why fuzzy or felted plants like lavender or silvery artemesia do well in hot, stressed situations. Anti-desiccant sprays are available for houseplants or for broad leaf evergreens when the soil freezes up north, but I don’t have much experience with them. Consider microclimates when planting.

6. Plants need more water on hot, bright days when the relative humidity is low, and evaporation is high. An insulating layer of organic mulch is good at reducing the evaporation.

7. Water needs vary with the type and maturity of the plant. Some vegetables and bulbs are tolerant of low soil moisture.

8. Set a rain gauge or two in an open area of the garden to learn how much water the garden receives each week and judge the need for supplemental irrigation accordingly. Use a straight-sided can or purchase a calibrated, easy to read gauge at a garden center.

9. Stand-alone containers or hanging baskets tend to dry out more quickly due to the combination of crowded, intensive planting and increased surface area along the sides of a porous pot, so they depend on careful monitoring. The smaller the container, the more frequently it needs water.

10. Sometimes a wilting plant does NOT need more water. This is true if plants are growing fast and the leaves get ahead of the roots' ability to provide them with water, and is easily corrected. Unfortunately it is also true if the roots are rotted from TOO MUCH water, which brings us back to the PWP.

Notably, young plants and new transplants require more moisture more often at the soil surface to help their root systems take hold. Water lightly but more frequently to accommodate their growth needs. Mature plantings with large root systems are best watered heavily but much less frequently than younger plants. The moisture soaks deep into the soil and encourages the roots to thrive. Follow watering guidelines in your municipality and happy gardening!