Dirt Divas

June 3, 2007

Smiling, a steaming cup of coffee in hand, you head to your back porch for a quiet moment.

Last weekend you planted containers with cheerful, blooming annuals so you expect your favorite retreat to be lovely this morning, and much appreciated after a hectic work week. But what a shock! Your wonderful flowers look like the neighbor's dog has used them for a urinal all week, or maybe they've been attacked by a band of malicious fairies with miniature propane torches! Most certainly there has been foul play!

Hardening off your plants is not a luxury. Dry, brownish leaves, on otherwise healthy looking plants recently put outdoors, is probably sunburn, caused by neglecting this important practice. The cell structure of house or greenhouse grown plants is not strong enough to tolerate full sun or strong winds, without first being acclimatized or hardened off.

Hardening begins two weeks prior to planting. The seedlings should be exposed to a week of cooler temperatures, have fertilizers withheld, and go nearly dry between waterings.

During the second week of hardening, normal watering is resumed, and the seedlings are placed out-of-doors the first day for only an hour or two in weak or filtered sun, under a tree or shrub, or even under a layer of burlap, in a location that is not in the full force of the wind. Each day for a week, the seedlings must be put out for a longer period of time until they can tolerate a full day of sun, and/or wind.

Having outlined the standard procedure for hardening off, I can't think of anyone who follows it precisely, except my own mother, whose heart is tenderly inclined towards her infants, the seedlings. Most of us, however, purchase our plants as burgeoning adolescents from a greenhouse or nursery.

How then to proceed? If the plants are out-of-doors when you acquire them, they may be partially hardened.

I still keep mine in less than full sun and wind for a few days to be safe. If the plants are not out-of-doors when you get them, they must go through the second week of the hardening process.

How much is too much? If the leaves are desiccated and brownish, the plant has had more sunbathing than required, and needs less sun for a couple of days. In case of wind, if the stems or leaves are snapped off, or the plant is lying prostrate, find a more sheltered location for a day or two. And don't forget your trees and shrubs. Although the leaves of shrubbery are not as susceptible to sun or wind as those of herbaceous plants, they too can succumb to harsh conditions, so it is best to harden them for a few days before planting.

If you're busy, try a shortcut. I put my seedlings to harden on the north side of my house, where they are under a tree (filtered sun), exposed to full sun only in the early morning and late evening (weak sun), and backed against a neighbor's shed (shelter from the wind). As I am essentially a lazy gardener, I thus avoid bringing the plants indoors, unless the nights are

too cool.

That brings us to temperature. Normally we begin hardening our plants when the weather is favorable. Nighttime temperatures in the 50s are good for most plants. This spring the nights have been so chilly, we must resist the urge to exile our plants before they are comfortable, concerned that they have time to flower or make produce before frost.

But remember, your plants will not put on much growth until nighttime temperatures climb above 50 degrees, so no hurry.

I diverge. We were discussing shortcuts. I have tried purchasing a plant that is not hardened and planting it immediately. I then placed a garden chair on its side south of, and close to, the plant, with the corner of the chair, where the seat and back meet, pointing south. This provides adequate shade and some support in case of wind. It is not at all attractive, but it helps when your gardening time is limited. Which brings us back to our weekend gardener.

Will those sun burnt plants be cheerful no more? Not to worry. They can be salvaged. Pick off the damaged leaves, keep the plants watered, and in two or three weeks, good cheer will return to the retreat; by then however, the mosquitoes will be too thick to step outside. But that is for another time. Happy hardening!

Hally Truelove is a Master Gardener and Plants Woman who lives and gardens in Wasilla with her two daughters, a handful of cats, a bunch of bunnies, some guinea pigs, a couple of dogs and a frog. Contact her at 376-0909.