Perennial Plant Care
Get your plants off to a good start with a few simple steps to improve your soil and keep them looking good by following these tips.
Soil Preparation
Keep in mind that perennials will be residents in your garden for many years so proper soil preparation is important to get your plants off to a good start.
If you are putting in a new ground level bed or a raised bed in an area that was previously devoted to lawn, you’ll need to get rid of the grass first. Lay out the shape of your new bed with a watering hose then use a sharp, flat edge spade to cut vertically into the sod along the outline of your bed. Then, cut the sod into one foot square sections. Slide your spade under each section to sever grass roots and remove it. Shake off the excess soil and put it in a wheelbarrow or cart. You can use the pieces to patch bare spots in your yard or add them to your compost pile.
Loosen the bare soil with a spading fork or rototiller then add organic matter and soil amendments. Composted organic matter is the most common and most effective ingredient to improve soil structure. Good garden soil should have at least 5% organic matter. Spread organic matter 2 to 6 inches deep across your entire bed. The amount you add will be determined by your original soil and by the kind of plants you want to grow. Moisture loving woodland plants need more organic matter than prairie natives. Organic matter can be added in the form of homemade compost, compost that you purchase by the bag or in bulk, well-rotted manure or leaf mold. Port Kells Nurseries carries composted material in bulk or in bags. As a rule of thumb, one cubic yard of organic material will cover 100 square feet to a depth of 3 inches.
Once all the organic matter and soil amendments have been spread across the top of the bed, mix them into the top eight inches of soil with a spading fork, shovel or tiller. Use a rigid steel, bowhead rake to smooth the surface of the bed.
If possible, allow the soil to stand unplanted for several weeks after you finish working with it. Stir the soil on top (an inch or two below the surface) every three to four days with a scuffle hoe or cultivate to eradicate fast-germinating weeds. This will reduce your weeding chores during the rest of the season.
Watering
Keep a close eye on all newly planted perennials during the first growing season. Many new perennials die because they get too much or too little water. The soil around their roots should be moist, but not soaking wet, for the first two weeks. For the next two weeks or so, water when the soil 2 inches below the surface is dry to the touch. After that, check the garden soil once a week and water if the soil 3 or 4 inches deep is dry.
To establish durable, deep root systems water slowly and deeply rather than frequently and shallowly. A good rule of thumb is that many perennials grow well with 1 inch of water per week. The water can come from natural rainfall or from irrigation.
Mulching
Mulch is a material that is layered on top of the soil to conserve moisture, to moderate soil temperature, and to keep soil from crusting during drought and compacting from prolonged rain. It is also a tremendous time and labour saver because it greatly reduces the need for weeding.
Organic mulches are ideal for perennial gardens because they break down over time to improve the soil structure. Materials such as compost, well-rotted manure, shredded leaves and fine textured bark chunks are good choices. You can make your own mulch by composting or by using a power tool called a shredder-chipper that turns yard waste into mulch.
A 2-inch layer of mulch should be spread over weed free beds after planting and, if you use them, after soaker hoses have been laid in place. Be careful to keep mulch pulled away from the crowns of plants. Crowns that are covered with moisture holding mulch tend to rot. Organic mulches can be reapplied every spring as long as you aren’t suffocating plants.
Grooming and Maintaining
Once perennials are established, they require minimal maintenance but this doesn’t mean that no care at all is needed. None of the jobs you’ll do to keep perennials in peak condition require a great deal of time and energy when taken individually. Some things you’ll simply do as you walk along– pause to pull out a stray weed or snap off a dead flower. Chores such as mulching, which require special preparation or equipment, you can do when you have extra time available.
These few simple care practices will keep perennials looking their best and keep your plants in bounds.
Thinning is when you reduce the density of a plant by cutting out shoots or stems at ground level. Thinning is done to get more light into the center of a plant, to promote better air circulation, or to improve the general shape of a plant. Plants prone to powdery mildew like asters, garden phlox, and bee balm usually benefit from thinning in the spring. You can also thin low growing perennials such as bugle weed, Bethlehem sage and lamb’s ear in the summer if high humidity threatens to rot the crown of plants.
Deadheading is a term for removing faded flowers. If left, many perennials bloom gloriously for a short period of time. Then they stop flowering and set seed. Deadheading interrupts this cycle. If faded flowers are removed before they set seed, many will send out another flush of blooms to try to complete the reproductive cycle. The blooms in the second display may not be as large or as numerous as the first, but they are certainly worth the effort. Other perennials that bloom over an extended period of time benefit from deadheading because it increases the number of flowers that are produced and the length of time over which they are produced. Deadheading also gives you some control over flowers that can be invasive because they self-seed.
Cutting back is a technique used to keep leggy plants more compact, to promote new foliage growth, or to coerce plants to bloom repeatedly. Sometimes you can avoid staking tall plants that are prone to flopping like tall asters if you cut them back by about one-half in early summer. This keeps plants shorter than normal and eliminates the need for staking. Other plants like spring-blooming dianthus and moss phlox should be cut back by one-half after they bloom to prevent them from opening up in the center or getting scraggly. Still other plants like columbine, Shasta daisy, goldenrod, hardy salvia, and yarrow should be cut back to the basal foliage (leaves that grow from the crown or base of the plant) after they finish flowering. This will promote lush new foliage growth and, sometimes, another round of flowers.
Division may be necessary to revitalize perennials that have been in the ground for three years or more. Signs that it’s time to divide include the following: reduced flowering (either in size or quantity), bare spots in the center of a clump (all of the growth takes place in a ring around the outer edges), stems that were once stout and self-supporting flop, plants that are crowding out neighbouring plants, or if you just want more of something to plant elsewhere or to give to a fellow gardener.
