Tennessee Perennial Dividing Calendar: When to Divide Perennials in Zone 6-7
Most perennials in Tennessee need to be divided every 2 to 4 years‚ depending on what USDA zone they are in and when they bloom․ If the plant blooms in spring‚ divide it early in the fall‚ from late September to mid-October․ If it blooms in summer or in fall‚ it is best to divide it early in the next spring when new growth emerges․ You might see transplant shock‚ wilted foliage or a plant that just sits there sulking for a season if the timing is wrong․
The state is in hardiness zones 6a to 8a․ This is not a completely helpful designation because‚ for example‚ when a person in Mountain City (zone 6a) has a shorter frost-free season than someone in Memphis (zone 8a)‚ the person in the latter city needs to wait until much later fall to divide․ In zones 6a-6b‚ you will want to have all your fall divisions completed by early October; in zones 7a-8a‚ you have until the end of October‚ or even early November‚ if the weather is fairly mild․
Signs your perennial needs dividing
Look for these clues before you grab a shovel:
- The center of the clump has died out‚ leaving a donut-shaped ring of healthy growth around a bare middle - The plant appears healthy‚ but it has been observed that flowering has greatly diminished․ - The plant has outgrown its space and is crowding neighbors - Stems are flopping over, or the clump looks congested and weak
Hostas‚ daylilies, and Shasta daisies are usually the first plants to show a donut hole pattern․ Ornamental grasses and black-eyed Susans just get floppy and will produce fewer flowers․
Step-by-Step: How to Divide Perennials Correctly
2․ Water the day before․ Dry‚ hard-packed clay (the usual Middle Tennessee soil) is hard to dig and repels roots․ The area is watered deeply 24 hours earlier to soften the soil and moisten the plant before it is divided․
2․ Dig wide‚ not just deep․ Starting about 6-8 inches (150-200 mm) from the edge of the clump‚ use a spade or garden fork to dig a circle around the clump․ Most perennial roots spread outwards before diving downwards‚ so digging too close can cut through the very roots you wish to keep․
3․ Look underneath the clump‚ and when the circle of dirt is loose enough‚ pry underneath it and pull the whole root ball out․ You can shake off or brush off some dirt so you can see the root structure and the natural partitions․
4․ Choose your divisions based on root type: - Fibrous roots (hostas‚ daylilies‚ coral bells): Pull apart by hand or slice through with a sharp knife if the clump is dense․ - For woody or thick crowns (such as peonies and Shasta daisies)‚ use a spade‚ or‚ alternatively‚ pick and use two garden forks back to back through the middle and pry apart․ - Tuberous roots (some irises): Cut clean with a knife‚ ensuring each section has at least one eye or growth point․
5․ Keep divisions sized right․ Each new division should contain 3-5 healthy shoots plus a suitable amount of root mass․ Buying smaller divisions gives you more plants‚ but they take longer to establish and are vulnerable in their first winter․
6․ Replant immediately‚ or within a few hours․ A root left out of the soil for even half a day loses its vigor․ If you can't plant them right away‚ wrap the divisions in wet burlap or put them in buckets with just a few inches of water in the bottom and store them in the shade․
7․ Water in thoroughly and mulch․ Watering in after replanting helps settle the soil around the roots and removes air pockets․ A 2-inch (51 mm) layer of mulch can help retain moisture and moderate soil temperature while the plant re-establishes․
Why Cloudy Days Are Better Than You'd Think If You're a Seed
One of the most common mistakes made by inexperienced home gardeners is to attempt the dividing process on a hot‚ sunny afternoon․ A newly-divided plant with less root structure cannot replace by natural transpiration the water lost from its surface area as quickly as it is lost through the roots from the soil․ It is best for sod to be put down on cloudy days‚ or in the early morning or evening when temperatures are cooler․ If a rainstorm is predicted within the next day or two‚ it is better‚ as the rain sets sod better than hand watering․
For Tennessee‚ perennial versus biennial plants․
Divide in early spring when the first new shoots appear (March in West TN‚ April in East TN): - Daylilies - Hostas - Ornamental grasses - Black-eyed Susan - Coneflower
Divide perennials in fall (September-October‚ depending on your zone): - Peonies - Iris - Shasta daisy - Hardy geraniums
Don't divide in summer․ Everything is lush and green‚ but a Tennessee summer's heat and humidity are more than your plant can handle when it is trying to grow new roots․
Easy Perennials For You To Add While Dividing
If you are already out in the garden splitting clumps‚ this is a perfect time to fill in any gaps or expand existing beds․ A wonderful option for shady areas is foamflower․ Its heart-shaped‚ deeply lobed leaves can form a dense groundcover‚ and in the humid summer air and loamy‚ well-draining soils of Tennessee‚ it thrives․ It spreads freely on its own too‚ so a handful of divisions will fill in a shady border in a couple of seasons․
In wooded or dappled shade, you can plant our Shade Fern Package with division of hostas or foamflower for a low-maintenance layered look․ If you're planning to divide some daylilies this year‚ try a few from our daylily collection in a color you don't already have․ They are tolerant of clay soil‚ and may be easily divided in a few years․
Things Some Competitors Ignore
If you are going to divide several varieties at once‚ label each division before putting it aside․ It goes without saying‚ although perhaps not until you've got six unmarked bunches of apparently identical-looking hosta roots in front of you․ Do not fertilize divided plants until they start growing again, since stressed roots may burn rather than benefit from fertilization․
Certainly, splitting perennials is not complicated‚ but how you schedule the operation according to your particular zone and the day of the week‚ and how closely you watch the weather, will make the difference between plants that will bounce back in a few weeks and those that will take a full growing season․
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