DIVIDING PLANTS
There are lots of reasons to divide plants, and when we say plants, we mean perennials, the plants that return year after year, but aren’t woody shrubs or trees. This includes most plants that grow from bulbs, tubers or corms. First, plants are divided or moved because they are overgrown, overcrowded, lack vigor or are in the wrong place — or because they’re so successful, you’d like more of them in another spot.
• The general rule is to divide summer- and fall-blooming plants in early spring, and spring bloomers in the fall. If in doubt, on when to divide which plants at
• Don’t divide lavender and sages; they’re too woody to take this well.
• Water the plant a day or two before you divide. Cut back any top dead growth from last season (compost the clippings). Move mulch away from the plant.
• Choose a cloudy, cooler day if you can. Also great: A day when moisture is forecast after you transplant.
• Prepare the new planting hole first; amend if needed. A wider hole is better than a deeper one for re-establishment. If you’re re-doing an entire planting bed, consider to help break up clay and conserve moisture. Read more at
• Use a shovel or spading fork to dig around all four sides of your target plant at least 4 to 6 inches away from the clump. Lift the entire clump with your shovel and carefully take it to its new home. If the clump is too heavy to move with the shovel, place it on a tarp or box and slide it over to the new planting site.
• For asters, bee balm, lamb’s ear and coneflower or other plants with roots that spread wide, tease root ball apart by hand or with knife or shears.
• The clumping root systems of day lilies, hostas, astilbes or ornamental grasses need to be cut apart with a sharp knife, shovel, even a saw for really large grasses. You can make many divisions from a single plant.
• Install divided plants at the same depth they occupied in their old homes. Firm soil around them. Water well, then mulch.
PROPAGATING PLANTS
Few gardeners say no to free plants (bindweed might be the only exception). Why not help the plants you have to make more of themselves?
• The easiest way is by taking a stem cutting. This new plant often matures and flowers more quickly than a seed-grown plant. You can propagate houseplants, outdoor geraniums, coleus, begonias and succulents — almost any healthy, growing plant.
• Here’s the preparation: Water the plant the day before and sterilize tools and containers with one part bleach to nine parts water (isopropyl alcohol works, too). You’ll need rooting hormone from a garden centers and lightweight, sterile potting soil (heavy soils retain too much water). Fill the pot with moistened, but not soaked, potting soil.
• Cut off a piece of a young, healthy stem up to 6 inches long, with 4 or 5 sets of leaves. Cut large leaves in half to prevent water loss.
• The bottom cut should be right at an angle below a leaf node (where the leaf joins the stem). Remove the two bottom sets of leaves.
• Create a small hole in the container of rooting hormone with a chop stick or pencil, and then insert the cutting in the product, getting it all around the stem. Place the cutting in the container; don’t let the leaves touch the soil. Several cuttings can be placed in the same container. Add water until it comes out of the bottom drainage holes.
• Place a clean plastic bag with a few small slits over the cuttings; keep the leaves from touching the plastic and place in a warm, indoor area out of direct sun.
• Roots will form in the next two to three weeks. Keep checking moisture levels; keep the soil damp, but not too wet.
• Remove the plastic. Once the plants are growing new leaves, you can begin hardening them off — gradually exposing them to outdoor light and conditions. Then they’re ready to be planted outdoors or repotted.
• You can also propagate some hardwood shrubs and trees — red-twig dogwood, willows, privet, roses and forsythia. Look for healthy shoots, about as thick as a pencil. Complete all the steps the same day, because cuttings that dry out will not root. Rooting for woody plants can take up to 6 weeks.
• You can also do this in late summer with woody herbs such as lavender, sage and rosemary. Plant lavender and sage outdoors, and use the new rosemary plants indoors all winter.
• Got African violet, grape, Swedish or English ivy, philodendron, coleus, basil, mint or impatiens? Cuttings from these babies will grow roots in just plain water. Cut 4- to 6-inch sections that contain a growing tip with two sets of leaves. Place in a bright location away from direct sun. Keep leaves out of the water, and change that water often. Once they’ve rooted, you can plant in the indoor or outdoor conditions they like.
IN THE LANDSCAPE
• Precipitation has been scarce; drying winds have not. Your landscape likely needs a deep soaking. Here’s where a long screwdriver you don’t otherwise need comes in handy. If the ground is moist, the tool will easily go in; if not, it’s time to water.
• Until your sprinkler system is turned on, drag out the hose, attach a sprinkler and water areas for 15 minutes, then move. After each soaking, do the screwdriver check.
• Water around the edges of tree branches using a sprinkler or soil needle. For evergreens, water 3 to 5 feet beyond the end of the branches. Water trees to 12 inches. More from Denver Water:
• Continue cleaning up the garden, cutting back spent foliage, refreshing mulch levels — you could even begin a new compost pile.
• Aerate the lawn a day or two after a good soaking rain or watering. Follow aeration with fertilization or wait until later in May to fertilize.
• Wait to remove spring bulb foliage until it’s complete spent after the plant has bloomed. Or just wait until the plants around the bulbs hide it.
• Continue planting bare root ornamentals and fruit — roses, strawberries, and raspberries. Asparagus crowns, potato tubers and direct seeding cool-season leafy vegetables, radish, arugula, turnip, parsnips, peas and onions. Have frost covers available for cold snaps.
• Despite those hot afternoons on the deck, it’s too early to plant warm-season vegetables (tomatoes) herbs (basil) and ornamentals (petunias). But you can plant hardened off cool-season plants — pansies, snap dragons — and direct seed flowers such as sweet peas and alyssum. It’s also a great time to plant lettuces, radishes, and other cool-season greens that come up quickly.
Betty Cahill: gardenpunchlist.blogspot.com
