Winter Garden Care: A Complete Guide for Tennessee Gardens
Now for the short version: winterize by cutting back dead stems after the first hard frost‚ adding 2 to 3 inches of mulch before the ground freezes‚ watering deep but very infrequently until the ground freezes (don't drown your plants in winter)‚ and don't fertilize until spring․ Get all four of those steps right and most of your perennials‚ shrubs‚ and young trees will survive a Tennessee winter․
That said‚ the details matter a lot more than the basics suggest‚ and different plants need different handling․ Here's what actually works‚ based on what our growers do every year across Middle‚ East‚ and West Tennessee․
Know Your Zone Before You Do Anything Else
In all‚ Tennessee has three USDA hardiness zones: 6b for the hills and mountains of extreme East Tennessee‚ 7a in the central part of state near Nashville‚ and 7b to 8a around Memphis and in the southwestern part of the state․ A plant that is hardy for Memphis may need special care in Gatlinburg․ The first frost occurs between October 15 and November 1‚ depending on where you live‚ and the last frost occurs sometime in mid-April․ The six months in between are your winter care window․
Mulch Is Doing More Than You Think
Many gardeners think mulch is only decorative․ It's not․ This layer‚ made of bark shavings‚ pine needles or straw 2 to 3 inches deep‚ should protect your perennials from freeze-thaw cycles that will kill them by freezing their roots․ It is not the cold that kills them in Tennessee․ It is when the ground freezes‚ thaws during one of our January warm spells‚ and then refreezes a few days later․ That cycle wrenches roots right out of the soil․
Mulch should be applied after the first hard frost‚ as mulching too early may prevent the soil from cooling and put off the time when your plants go dormant․ If you apply mulch‚ keep it an inch or two away from the plant crown‚ so moisture does not amass on the stem causing rot․
Watering Doesn't Stop‚ It Just Slows Down
Watering every 2 to 3 weeks is necessary unless there is heavy rain․ This is because even in winter‚ when dormant‚ plants will still lose water from their roots‚ and Tennessee has meaningful dry periods in November and February․ It's easier to do this in late morning rather than evening‚ when the moisture on the foliage will have enough time to dry before it freezes․ Container plants will dry out more quickly than ground plants‚ so check weekly․
Do not water a day before a hard freeze‚ the water around the roots refreezes harder and causes more damage than not watering․
Cover Young and Tender Plants‚ Not Everything
New trees‚ shrubs and herbs and perennials less than a year old in the ground do not have roots that can tolerate a hard freeze․ Wrap tree trunks with burlap or tree wrap․ Cover your tender perennials with frost cloth sheets or bedsheets on nights when temperatures remain below 25 degrees Fahrenheit (−4 degrees Celsius)․ If a warming occurs during the day‚ uncover plants as moisture can cause more damage than the frost if trapped beneath the covering during the day․
Established natives and hardy perennials usually don't need this kind of work․ Save it for the ones that actually need it․
Do Not Prune Heavily Yet
Fall pruning is a common mistake․ Pruning a plant back in October or November produces new growth that has no chance of hardening off before the first freeze and has not been hardened off by the time winter arrives․ Major cutback should be done in late winter or very early spring‚ when you know the most severe cold has ended; however‚ any dead‚ diseased‚ or damaged stems can be removed any time in the year․
Milkweed: Support the Monarchs Through Winter Too
Although milkweed is as easy to grow as most perennials‚ as a genuine monarch host plant it requires a little extra consideration․ Common milkweed is hardy and requires little special care‚ except for gathering up the dead stalks and leaves once they turn brown to prevent fungal infections from wintering in the debris․ Butterfly milkweed is just as hardy; once the leaves begin to die after the first frost‚ cut it back to within 5 inches of the ground so it does not waste energy while trying to leaf back out․
The tropical milkweed varieties‚ since they are not as hardy as the native varieties‚ and thus would not grow well in the winters of Tennessee‚ need real protection․ If your tropical milkweeds are in pots‚ you can move the pots into a garage or an unheated storage shed when the nights drop below freezing․ You can mulch in-ground milkweed plants in the fall after the first frost․ Water sparingly over the winter months (enough that the soil isn't dust)‚ and do not fertilize beyond September․ Late fertilization pushes up tender new growth that has no time to harden before the cold gets it․ If you'd like to expand your plantings next year‚ TN Nursery has a whole lot of native milkweeds bred to handle your winters (no fuss of tropical varieties needing extra warmth and protection)․
Creeping Phlox Needs Almost Nothing ‚ Which Is the Point
Creeping phlox is about as low-maintenance for winter as it gets․ It's evergreen‚ so don't cut it back because those leaves are providing natural insulation for the crown all winter․ Remove any dead or diseased foliage you see․ Then put down a 3-inch layer of mulch‚ such as pine needles or shredded leaves‚ and only water as needed during the winter months․ Container-grown phlox requires a little more attention‚ as the temperature of the roots can fluctuate more easily than those of the same plants in the ground․ Skip fall fertilizer here too‚ for the same reasons as everything else on this list․
One Last Thing Most Guides Skip
Check all your plants after every freeze-thaw cycle‚ not just at the end of November and at the beginning of spring․ A quick stroll through the garden after a warm snap followed by a hard freeze allows you to identify heaved roots and press them back into the ground before they get damaged․ It takes five minutes‚ and may save plants that look fine right up until they don't leaf out in April․
Winter prep is not a glamorous task by any stretch of the imagination‚ but your March garden will be much improved because of the work you've done now‚ and your crops will be hardier come next year․
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