It’s time for dividing iris and day lilies

August has arrived and it is the month for dividing iris and day lilies. As the weather has been dry, these plants should be watered well before lifting and dividing. They will dig easier when soil is moist and roots are not so easily damaged.

Iris will outgrow their space in the garden and bloom will be reduced if they are not divided every three or five years. They can also become weedy and unsightly. When you dig an iris clump, the healthy new plants will be to the outside of the old clump. You can discard the old rhizomes; old rhizomes are usually nearest the fan of leaves. Iris are shallow rooted and are easy to divide.

Have your new spot ready by adding compost or peat moss and a little bone meal to the soil. If you want to plant them in the same area, this can be done by digging all the plants, working up the bed and planting back again after replenishing the soil.

Cut the tops to five or six inches if you wish, but the leaves can be left on although they are easier to handle if leaves are cut back. Iris rhizomes need to be planted shallowly with one third of the root above the soil. Plant the leaves outward toward the edge of the bed or in a circle of three to five with the leaves to the outside of the circle. Tamp down hard with your foot, water well and you are finished. They do not require too much water, but if it is dry, they should be watered. Fertilize again in spring with bone meal and you are finished. I advise growers to mulch the first winter to prevent winter kill to the newly formed roots. There are new reblooming iris on the market and am anxious to try them. Now is also the time to plant new iris plants.

Day lilies are named because each bloom lasts just one day. They are a very tough, long-lived perennial, but they too need to be divided every few years. This task is not quite as easy as the iris as they have an extensive root system requiring digging to a depth of 10 to 12 inches.

Day lilies can be divided by chopping apart with a shovel or pulling apart by inserting two spading forks back to back and prying them apart. You will save more divisions with the later method. Each division should be at least six inches across. Plant the roots the same depth as they were in the original bed. Plant in a new bed that has added compost or peat moss and bone meal.

Day lilies are planted similar to the method used for strawberries. After having a bed worked at least 18 inches deep, make a little mound to spread the roots around with the crown in the center. If some roots are really long, cut them off as you do not want to coil roots around in a circle. Add a little bone meal, according to package directions, water well and tamp hard with your foot. They can be mulched, being careful not to get mulch over the crowns. This helps hold moisture at planting time and protects them from winter’s thawing and freezing. I leave the tops on, but you could cut them back slightly. I would add additional mulch, such as straw, applied after the first hard frost for additional winter protection.

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