Dividing Perennials in Your Garden
You can divide perennials whenever the ground isn't frozen, but the best time of year for division is a couple of months before severely cold or hot weather sets in. You want to give newly planted sections a chance to settle in and get a strong start before they have to cope with weather extremes.
If you live in a cold climate, divide your perennials either in spring, when the newly emerging foliage is up several inches, or in late summer, six to eight weeks before temperatures are expected to drop below freezing. In warm-winter regions, divide your perennials in the fall.
To divide perennials, follow these steps:
1. Soak the ground a few days before you plan to work, if the soil is hard and dry.
Ideally, the soil should be soft enough that you can dig into it easily with a shovel or spading fork, but not so muddy that it sticks to you or your tools.
2. Cut all the stems down to 4 to 6 inches (10 to 15 cm) from the ground.
3. Dig up the whole clump.
Cut a circle a few inches outside the edge of the clump you're planning to divide. Don't worry if you cut roots — they grow back.
4. Place the whole clump on a tarp or an old sheet and look it over.
Some plants come apart as easily as pull-apart cinnamon rolls. Others are impossibly dense and tangled. Tug at the crowns and see what happens. If the plant doesn't come apart easily, you have two options:
• Soak the whole plant in a large bucket for a few hours to soften the soil and then rinse it off with a hose. Now, you can untangle the exposed roots by using your fingers to separate the individual crowns.
• Use a shovel or a sharp knife to slice the root mass into as many chunks as you need. For really tough roots, you may need to use an ax or hand saw.
5. Pull off and discard all the dead stuff and any tough, woody parts.
Make certain that each division has both roots and leaves. Keep the biggest, healthiest chunks and compost the rest if it's disease-free.
6. Replant and water thoroughly.