Answer: Armeria (thrift) spreads slowly, but eventually needs dividing, especially when the center becomes bare! There are two ways of dividing thrift. You can dig systematically beginning at one edge of the bed and dividing the live from the dead, replanting the healthy parts, or you can dig each clump, cut away the live ends to replant and toss out the dead centers. Whichever way you launch your attack, be sure to dig deeply enough to unearth as much of the root mass as possible. The less damage you do to the roots, the faster the plants will recover. I've found that thoroughly watering the area 24-hours prior to digging and dividing makes the process go much easier.
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