The Ornamental Garden in June
With the arrival of the summer solstice on June 20 comes hotter, steamier weather and the most active season of the year for dedicated gardeners. As spring planting winds down, shift your focus to the following tasks:
Maintain Your Ornamental Beds
- Weed your flowerbeds at least once a week, more often if you have the time and the inclination.
- Deadhead spent blossoms on annuals to keep plants looking tidy and to encourage re-blooming.
- Water plants deeply and infrequently at the root level. This is particularly important for newly planted ornamentals. If you use a sprinkler system, try to water in the mornings so that foliage can dry off during the day.
Monitor Ornamentals for Pests and Disease
- Japanese beetles – The Japanese beetle is one of the most devastating landscape pests in central Virginia at this time of year. The grubs pupate in the soil in spring and emerge as adults in June and July with voracious appetites. They arrive in groups and can quickly skeletonize the leaves of many ornamental plants. The best strategy for managing these beetles is prevention and early detection. When the pests first appear in the landscape, immediately remove them from affected plants. The logic in doing this is that the presence of the beetles on a plant attracts more beetles. A quick “organic” way to dispense with them is to pick them off plants by hand early in the morning when they are sluggish and drop them into a bucket of soapy water. Virginia Cooperative Extension Publication ENTO-97NP, Japanese Beetle, provides information on this pest and strategies for controlling it. For additional information, see University of Kentucky Cooperative Extension Service Publication ENTFACT-451, Japanese Beetles in the Urban Landscape. It includes lists of landscape plants that are seldom damaged by Japanese beetles as well as plants that are likely to be attacked by them.
- Rabbits — It’s easy to blame deer for damage to your ornamentals, but rabbits tend to like the same plants. Some strategies for keeping bunnies out of your garden include:
- Deer repellents. Rabbits and deer belong to the same mammal family and any organic spray that contains rotten eggs and hot pepper should repel both critters. The downside to repellents is that most of them need to be re-applied after heavy rains. TIP: Like deer, rabbits also don’t like the scent of blood meal or Milorganite fertilizer.
- Fences or other physical barriers. If you have plants that are prone to rabbit browsing, install a physical barrier of chicken wire or other small gauge wire. If that’s not a practical solution, you may need to consider installing a rabbit-proof fence around your entire garden. To be effective, the fence needs to be 3 feet tall and constructed of chicken wire or other wire with openings no more than one inch wide. Rabbits can tunnel, so make sure the bottom of the fence is buried about 6 inches deep.
- Rabbit-resistant plants. Rabbits don’t normally bother Allium, Artemisia, Achillea (yarrow), Monarda, Baptisia, Irises, Salvia, lavender, monkshood, Russian sage, lilacs, or viburnums. For additional rabbit-resistant plantings, check out Penn State’s Cooperative Extension Publication on Rabbit-Resistant Garden and Landscape Plants.
- Dogs. If you don’t have a dog, encourage your friends with dogs to visit you often.
Collect and Save Seeds
When you’re not busy battling pests in the garden, try collecting and saving seeds. Start with spring-blooming plants such as Dianthus, sweet William, poppies, and bleeding hearts. Collect the seeds after the flowers have faded and seeds are dark brown or black. Spread the seeds out and allow them to dry thoroughly so that they don’t become moldy. Place the dried seeds in paper envelopes or air-tight glass jars and label and date them. Store the seeds in a cool, dry, dark place over winter. Some people like to store seeds in their refrigerators. Remember: open-pollinated species will come back true from seeds. Hybrids will not.
Consider yourself to be an advanced seed saver if you try your luck with trickier seeds that require stratification or scarification or both in order to achieve germination. For example, collect Baptisia seeds after the pods darken and begin to split open. If you plant the seeds ¼ inch deep while they are fresh, they should germinate within about 2 weeks. However, if you wait until later in the season to germinate them, they must be chilled (stratified) for 6 to 12 weeks first. Then, before planting them, scarify them (lightly scratch with sandpaper or nick the seed coat). As an alternative to scarification, pour hot water over the seeds and let them soak for about 24 hours before planting them.
Salvage Root-bound Plants
As prime planting season winds down, you’re likely to encounter lots of “bargain” plants for sale. Make sure you’re buying healthy specimens and not badly stressed plants. I’m referring specifically to root-bound plants that have outgrown their pots and not been re-potted into larger containers. Being root-bound (or pot-bound) prevents plants from taking up water and nutrients, stunts the plant’s growth, and may eventually kill it. Root-bound plants are easy to spot. They’re the ones with roots growing out of the pot’s drainage holes. If you want to try salvaging such a plant, cut off the roots that have emerged through the drainage holes and remove the plant from the container. You’ll see dense masses of matted and tangled roots. In some cases, the roots may be coiled in a circle at the bottom of the pot. If the roots are brown or black, they are probably dead. If they are white, they are alive. Cut off any extremely long coiled roots near the root ball. Using a sharp knife or hand pruners, make several vertical cuts through the root ball about 1 to 2 inches deep (depending on the size of the root ball). While that sounds drastic, it’s necessary in order to stimulate new root growth. It help the roots grow out or down into the soil rather than around in a circle.
After daffodil foliage has died back, use a shovel or garden spade to dig up the bulbs. Dig several inches away from the clump to avoid damaging the bulbs and their offsets. Bulbs are usually planted fairly deep, so be prepared to dig down to about the depth of your spade. Lift the clump of bulbs from the ground being careful not to damage the roots. Gently twist the bulbs apart with your fingers. Discard any that look damaged or diseased. Re-plant the bulbs in a sunny spot with good drainage. Mix in a good amount of compost or other organic matter before you replant them. Plant them three times deeper than the circumference of the bulb. In other words, if the bulb measures two inches around its middle, plant it six inches deep. If you replant any of the bulbs in the original location, incorporate some fertilizer in the planting site to re-build nutrient levels.
Propagate Stem Cuttings
Late spring to early summer is a good time to propagate stem cuttings of woody ornamental plants. Camellia, cotoneaster, viburnum, deutzia, and lilac are examples of plants that can be easily propagated this way. Softwood cuttings should be taken from tender new growth on woody plants, just as it begins to harden. To learn how to propagate plants, refer to Virginia Cooperative Extension’s publication 426-002 on Propagation by Cuttings, Layering and Division (pubs.ext.vt.edu/426/426-002).
Remove Spent Rhododendron Blooms
Now that rhododendrons have finished blooming, carefully remove the old blooms. This will promote better blooming next year. In addition, it will give the plant a tidier appearance and will help prevent insect infestations. The best time to deadhead is within 2 to 3 weeks after the blooms have faded. The technique for deadheading is simple: Grasp the spent blossom cluster (called a truss) and carefully pinch it off or push it aside with your thumb. This will reveal the developing flower buds for next year’s flowers. Be careful not to injure those as you remove this year’s dead flower clusters.
If you’re looking for something different for your garden, try growing succulents. Many species of Sedum, Sempervivum, and Euphorbia can tolerate our summer humidity and are hardy enough to withstand our USDA Zone 7 winters. Sedums, in particular, are drought tolerant once established, deer resistant, and may be used as an alternative to mulch for smothering weeds. They are low- growing, colorful, and, in some cases, finely textured. A few that are readily available in garden centers include ‘John Creech’, ‘Blue Carpet’, ‘Angelina’, ‘Lime Zinger’, and ‘Dragon’s Blood’. Give them a sunny spot and plant them in well-drained soil. Most Sedums are slow growing but a few are aggressive growers. Fortunately, they are easy to pull out. Just don’t let them crawl over into your lawn where they may be more difficult to remove.
Soil that drains well, especially in the winter, is key to growing succulents successfully. To improve drainage, mix some pea gravel or horticultural grit (which is smaller than pea gravel but coarser than sand) into the soil. You may also need to build up or mound the soil so that water flows away from the plants. If you select succulents that are not hardy enough for our winter weather, try growing them in containers in soil that has been formulated for cacti and succulents and then bring the containers indoors for winter.
Consider Designing and Installing a Rain Garden
More and more people are installing rain gardens to capture rainfall and storm-water runoff. If you’re in the process of planning a rain garden, choose plants for it that can tolerate occasional flooding as well as long periods of dry weather. Va. Coop. Ext. Publication 426-043 on Rain Garden Plants recommends one plant species for every 10 to 20 square feet. In the example they give, a 140-square-foot garden should have 7 to 14 different plant species, consisting of a mix of tall, medium and low-growing species. A sampling of some of the plants recommended for rain gardens include:
- Trees: Black gum (Nyssa sylvatica), Carolina silverbell (Halesia tetraptera) and hornbeam (Carpinus caroliniana)
- Shrubs: American beautyberry (Callicarpa Americana), spicebush (Lindera benzoin), and winterberry (Ilex verticillata)
- Perennials: Beard tongue (Penstemon), black-eyed Susan (Rudbeckia), and blue lobelia (Lobelia siphilitica)
- Ferns: Cinnamon Fern (Osmunda cinnamomea), holly fern (Crytomium falcatum), and royal fern (Osmunda regalis)
- Grasses: Feather reed grass (Calamagrostis acutiflora), switchgrass (Panicum virgatum), and foxtail grass (Alopecurus pratensis)
Eradicate Poison Ivy
Are you familiar with the rhyme “Leaves of three, leave them be?” The reference is to poison ivy. On average, it takes about 2 to 3 weeks to recover from the rash caused by contact with urushiol (pronounced u-ROO-she-ol), the active ingredient in the plant’s sap. If you find this noxious vine sprouting in your landscape, here’s how to get rid of it safely: Loosen the soil around the roots so that they will be easier to pull. Slip a plastic trash bag over your gloved hand. Grasp the plant through the plastic bag and pull it out by its roots. Pull the trash bag up over the plant, securely tie the bag, and place it in the trash. DO NOT COMPOST OR BURN THIS PLANT.