Dividing Perennials Assures Many More Years Of Color

Most perennial flower plants are best divided or moved either in fall or early spring, but the three beauties - Oriental poppy, bearded iris, and Madonna lily - go dormant in summer, so are best multiplied now.

For example, as poppy plants age, they become woody at their centers, and flowering declines. Digging up an old clump of poppies, then discarding the old crowns and saving and replanting the young crowns, is a prelude to many more years of flamboyant spring flowers. The young crowns, preferably left in groups of three, need a covering of 3 inches of soil.

If your clump of poppies is not so old as to need rejuvenation, you could just grub out a few root cuttings while hardly disturbing the plant.

Pieces of roots a quarter-inch thick and 3 inches long can be planted either horizontally, with a 1-inch covering of soil, or vertically, with their tops just beneath the surface. These cuttings flower by their second season.

Bearded iris and Madonna lily are similar to Oriental poppy in going dormant in midsummer, but that’s the end of any similarity in growth habits among these plants. Bearded iris spreads by means of finger-thick rhizomes that creep along the top of the ground, and lily forms a clump of underground bulbs.

To make new plants from, or to rejuvenate, an old iris clump, first dig up the rhizomes.

The best time to do this is earlier in the season, right after the plants finish flowering, but doing it now is almost as satisfactory and still allows time for roots to take hold before winter.

As with the poppy, discard old portions of the iris. Each young portion should have two or three fans of leaves attached. Completely remove any withered or old leaves, and shear healthy leaves to a length of a few inches.

In heavy soils, replant the thick rhizomes horizontally and halfway buried, so a plant with its short fan of upright leaves looks like a duck swimming on water. If your soil is well-drained, set the rhizomes beneath just a thin covering of soil.

A lily plant, like the other two plants, becomes overcrowded, in this case with bulbs. Again, the best time for digging, dividing, then replanting is just after the flowers fade, when the plants take a breather before growing new roots and leaves. Lily bulbs lack the protective covering of bulbs such as tulips and daffodils, so the less time a lily bulb is out of the soil, the better. Reset lily bulbs in the soil 8 inches apart under a covering of 2 inches of soil.

Expect little or no show of flowers the year following transplanting poppy, iris or lily, because the plants need time to establish strong roots systems and build up energy reserves. After that, though, enjoy years and years of color.