Garden Tips: Perennial flowers need attention

When perennial flowers first became trendy, many gardeners had the impression that perennials were low or no-maintenance plants. Since then, we have learned that perennials require regular care to keep them coming back each year.

At this time of year, most perennials are quietly resting in the garden, but as the weather starts warming, there are some important tasks that need to be performed. The first is cutting back dead growth killed by fall frost. If there are no signs of green growth at a perennial’s base, cut the dead growth back to the ground. Some types of perennials will already have visible green growth. Carefully remove dead leaves and stems to uncover the new growth.

Weeding is also on the spring chore list. Winter weeds will grow quickly once the weather warms. If you see any, get them out of there before they get a chance to grow. Just make sure you are pulling weeds and not perennials.

With weeds in mind, spring is an opportune time to renew the wood chip or bark mulch around plants. Because of our moist winter conditions, organic mulches in will have had the chance to break down, enriching the soil but leaving a layer of mulch that may not be thick enough to provide good weed control. Check the depth of mulch and apply more if the layer is less than 3 to 4 inches thick for coarse mulches, or less than 2 to 3 inches for finely textured mulches.

Organic mulches help retain moisture and control weeds, but care must be taken not to overdo it. Too much mulch can kill plants, especially if it is placed over the crowns (bases) of the plants.

Another springtime task in the perennial garden is division. Over time, most perennials will need to be divided. The frequency of division varies from type to type, becoming evident when the center of a clump starts to die out, or the plant’s flower production has significantly declined. Perennials may also need to be divided if they are outgrowing their allotted space. To find the typical frequency of division for each kind of perennial, check a reliable garden reference.

Division is best in the spring once plants have started to grow, but before the new growth is more than 4 to 5 inches tall. Early season bloomers, such as Oriental poppies, peonies, iris and Asiatic lilies, are an exception. They should be divided after flowering in late summer or early fall. There are also perennials that do not like to be divided or moved, such as flax, lupine, Russian sage, evening primrose and butterfly weed.

Division tends to be a rigorous task. It requires digging up the plant, washing soil from the roots and crown, removing dead parts and then dividing live portion into several clumps. Sometimes division can be accomplished by gently pulling the plant apart using garden forks, but more often, the process involves using a sharp garden knife or spade to cut apart the clump and remove the dead portions. Again, a good garden reference can clue you in what may be needed when dividing each kind of perennial. The newly separated divisions should be replanted right away at the same level that they were growing previously, and then watered in to settle the soil.

It is still a bit early and the soil is too wet to be taking on these perennial flower chores today, but it will not be long before you can get started.

This story was originally published January 23, 2016 at 11:29 PM with the headline "Garden Tips: Perennial flowers need attention."