Deseret Nursery Perennial Farm

Dividing and Reinvigorating

Overtime, many perennials can eventually wear themselves out. The clumps may also thicken to the point that the plant looses its classic look, or stems and branches begin to flop, nest open or develop dead zones. This usually occurs after a three to five year time frame.  When this occurs the plant can be divided.

Dividing the clump is best accomplished in the spring on most plants. As the plant emerges from winter dormancy, take a shovel and slice through the center of the clump while it is in the ground. Then slice around the parameter of the clump and under it, while it is in the ground. The pieces of the clump can then be lifted out of the ground intact and replanted. A large clump can be quartered, or even more. Examples would include Gaillardia, Salvia, and upright Sedums and ornamental grasses.

Perennials that are woody or are sub shrubs typically cannot be divided readily, their branches are best cut down or back by 30% to reinvigorate the stems and form. Examples would include Russian Sage, and Agastache.

Perennials that are prostrate or low growing can be reinvigorated by cutting the foliage inward by 50% such as creeping phlox, or lightly shearing the top of the foliage as in the case of Aubrieta or Rock Cress.

A plants purpose in life is to procreate by producing seed.  Once it has done this, it says to itself "I have done my job, and it takes a break, or checks out.  However, if the blossoms are removed as they fade, it thwarts this endeavor, and the plant tries to boom again in order to produce seed. The removal of faded blooms and stalks, and the effectiveness of this is not universal or worth while on all plants. And while it is always beneficial, it is not always critical. Sometimes it will cause the plant to rebloom significantly, and other times it is not worth the effort. Many plant tags will state that it "blooms all summer," And while technially you can find a bloom later on in the season, realistically perennials bloom 6-8 weeks, and if they have a second flush of blooms, it is not as generous as the first.

However, removing faded flower stems will always improve the general appearance of the perennial, and can help divert energy to the roots for growth for the following year. On certain perennials the process of bearing seed can  also wear the plant out or down. 

Perennials definately benefit from fertilization, although they are not high consumers of it.  We recommend that this takes place in the fall, although it can be done at anytime of the season. In low water situations, a fall fertilization is made effective by the winter snow melt transporting the nutrients.  A granular fertilizer of 16-16-8, or a 10-10-10 is appropriate.

The third major component of xeriscaping is mulching.  Mulching is the placing of a thick layer of organic compost/matter on top of the soil aroung the plants. This would consist of decorative bark, composted yard waste, or ground up aged wood chips.  We emphasize that this needs to be a thick layer. 4 plus inches. 

 In addition to a weed supressant, It helps to significantly retain moisture in the soil. It also helps to keep the roots cool during the heat of the summer.  Quite often, if the roots are cool, the plant  is much happier. Furthermore, the reduction in water expenditures significantly defrays the cost of placing of mulches, and its replenishing on an annual basis.  

The broad scale use of gravel as a mulch or ground covering should be minimized. The negatve effects of heat accumulation and radiation from it are many in the landscape and in the urban evironment in gereral.  It should rarely exceed 50% of the ground area, and should not be placed imediately around the plants.