Late September finds most summer annuals looking a bit ragged around the edges and, really, who can blame them? For several months the plants have given their all–flowering and flourishing–despite the cooler-than-normal temperatures.
But there's a time for everything and now it's time to redo container gardens. Newly planted pots should last well into November and, perhaps, until Thanksgiving if we're lucky.
In my column about a month ago I detailed more than 30 plants with outstanding fall features. With the exception of some tender annuals, all are terrific options for a fall container garden and, in addition, there is the bonus of using the plants later in the garden.
Listed below are additional design ideas for fall container gardens. • Plant frost-tolerant herbs like thyme and rosemary. • Consider small-sized woody trees and shrubs. • Try an evergreen (also easily transitioned to a winter container garden). A lovely and graceful plant with bright foliage is 'King's Gold' False Cypress (Chamaecyparis pisifera 'King's Gold'). • A distinctive accent is a grouping of berried branches. Look for rose hips, cranberrybush viburnum, crab apple (love the cultivars with golden fruit), bayberry, glossy black chokeberry or bittersweet which also can be curled artfully about the pots. • Display containers with cornstalks, gourds or big, colorful pumpkins.
Frosts and freezes. Light frost. Killing frost. Hard freeze. Confusing terms, aren't they?
Technically, frost and freeze have different definitions but often, in the vernacular, are used interchangeably.
In the October/November 2009 issue of Horticulture magazine, Dr. Ed Brotak, a former meteorology professor, wrote, "Frost is the formation of white ice crystals on an exposed outside surface." He continued, "The major concern is for the water inside the plant. If this water freezes, then plant tissue damage is possible, if not likely." And while frost itself doesn't harm plants it can be "a good warning sign that plant damage has occurred or may occur."
Now that the terminology is clarified, what are important dates for our part of the country?
The best data I found is in an exhaustive report the National Climatic Data Center of the National Oceanic and Atmospheric Administration compiled for 3,106 locations from 1951 – 1980. The report defines the various freezes as follows:
Light Freeze: 29 – 32. Tender plants killed with little destructive effect on other vegetation.
Moderate Freeze: 25 – 28. Widely destructive effect on most vegetation with heavy damage to fruit blossoms, tender and semi-hardy plants.
Severe Freeze: 24 or less. Heavy damage to most plants. The ground freezes solid with the depth of the frozen ground dependent on the duration and severity of the freeze, soil moisture and soil type.
Below is the chart for Hinckley with probability percentages for 36-, 32- and 28-degree temperatures. (I didn't think it necessary to check microfiche for temperatures of 24, 20 and 16!) The probabilities for 36 are included because temperature readings are taken about 5' above the ground and surface temperatures (i.e., where plant parts are) can be 4 – 8 degrees lower.
TEMPERATURE 10% PROBABILITY 50% PROBABILITY 90% PROBABILITY 36 Aug 23 Sep 8 Sep 23 32 Sep 9 Sep 19 Sep 29 28 Sep 15 Sep 28 Oct 10
While so far this has been a lovely September, clearly our warm days are numbered. Enjoy them while you can!
Design Journal. Some years I can't bear to rip out a geranium or gorgeous coleus that grew faithfully for me all summer. Somehow it doesn't seem fair. Instead of composting favorites this year, grab a pretty vase (I especially like antique aqua canning jars), fill with water and root cuttings.
It's a breeze. Snip about 4" – 6" off the tip. Remove foliage that will be under water and place the jar in an east window or bright, indirect light. Soon, cute white roots will form and the cuttings can then be transplanted into small pots.
In addition to geraniums and coleus, try impatiens, fuchsias, wax begonias, annual vinca vines, lemon verbena, oregano and sage.
This column also appeared in the Askov American, Askov, Minnesota, Kanabec County Times, Mora, Minnesota, and Pine City Pioneer, Pine City, Minnesota.
