June 2024 Hort Tips
View the June 2024 Hort Tip articles below.
Garden Tips for June!
David Hillock, Senior Extension Specialist
General Landscape
- Find someone to water plants in the house and garden while on vacation. Harvesting vegetables and mowing the lawn are a must and imply that someone is home.
- Mulch ornamentals, vegetables, and annuals to reduce soil crusting, and to regulate temperatures and moisture during hot summer months. Mulching will reduce about 70 percent of the summer yard maintenance.
- Remain alert for insect damage. Add spider mite to the list. The foliage of most plants becomes pale and speckled; juniper foliage turns a pale yellowish color. Shake a branch over white paper and watch for tiny specks that crawl. Watch for first generation fall webworm. (EPP-7306)
- Continue to water the landscape deeply as needed. Apply at least one inch of water each time.
Turfgrass
- Fertilize warm-season grasses at 0.5 to 1 lb. N per 1,000 square feet. Do not fertilize fescue and other cool-season grasses during the summer.
- Dollar spot disease of lawns can first become visible in mid-May. Make certain fertilizer applications have been adequate before applying a fungicide. (EPP-7658)
- Seeding of warm-season grasses should be completed by the end of June (through July for improved varieties such as Monaco, Yukon, and Riviera to reduce winterkill losses. (HLA-6419)
- Brown patch disease of cool-season grasses can be a problem, avoid over-watering these grasses. (HLA-6420)
- White grubs will soon be emerging as adult June Beetles. Watch for high populations that can indicate potential damage from later life cycle stages as grubs in the summer. Apply preventative white grub treatments from late April to early June.
- Post-emergent control of crabgrass and summer annual grasses is best performed on young plants. (HLA-6420)
- Conduct the simple irrigation audit in your home lawn. This simple procedure may save you money, keep plants healthier and help conserve Oklahoma water resources. (HLA-6610)
- Aerification of warm-season grasses like bermudagrass should be done in summer months if needed to control compaction.
Fruit and Nut
- Renovate overgrown strawberry beds after the last harvest. Start by setting your lawnmower to its highest setting and mow off the foliage. Next thin crowns 12-24 inches apart. Apply recommended fertilizer, preemergence herbicide if needed and keep watered. (HLA-6214)
Trees and Shrubs
- Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk and remove the least desirable trunk as soon as it is noticed. (HLA-6415)
- Pine needle disease treatments are needed again in mid-June.
- Remove tree wraps during the summer to avoid potential disease and insect buildup.
- Softwood cuttings from new growth of many shrubs will root if propagated in a moist shady spot.
- Protect trees from lawnmowers and weed eaters by mulching or using protective aerated covers.
Flowers
- Pinch back leggy annuals to encourage new growth. Fertilize and water appropriately.
- Feed established mums and other perennials.
- When picking fresh roses or removing faded ones, cut back to a leaflet facing the outside of the bush to encourage open growth and air circulation.
- Stake tall perennials before toppling winds arise.
Earth: Beneficial Fungi
David Hillock
Fungi are an incredibly diverse kingdom of organisms. As gardeners, we are familiar with the edible forms of fungi that we may try growing ourselves or use in cooking. We also deal regularly with fungi that produce plant diseases in the landscape. There are also many beneficial fungi that live in the soil and benefit the plants we grow.
The two main types of beneficial fungi below ground are saprophytes and mycorrhizae. Saprophytic fungi grow on decaying matter such as leaf litter, fallen trees, and dead animals. They help break down these materials into organic matter, thus replenishing the soil. Mycorrhizae are fungi that develop a partnership or symbiosis with living plants, such as trees and grasses. Their presence increases the effectiveness of the plant’s roots. The fungi deliver minerals and nutrients from the soil to the plant roots, which in turn supply the mycorrhizae with water and carbohydrates. Two types of mycorrhizae are ectomycorrhizae, which grow outside of roots and endomycorrhizae, also called arbuscular mycorrhizae, which have highly branched hyphae that penetrate root cells.
As much as 90% of all plant species have mycorrhizal associations. Some plants, like pine trees, are highly dependent upon mycorrhizal fungi for growth. The prairie ecosystem is also dependent upon mycorrhizae.
Mycorrhizae are an important component of soil. The long, threadlike hyphae help hold soil particles together. With all the fungi in the soil it must have an impact on soil structure. They help support soil structure and healthy soils. We can protect these beneficial fungi in our garden soils through several practices:
- Limit fertilizer applications.
- Utilize organic fertilizers.
- Practice low-till or no-till gardening.
- Avoid fungicide use, especially soil drenches.
Resource
Oklahoma Gardening segment, June 30 – July 1, 2012, Information Sheet (#3853), with Dr. Gail Wilson, Associate Professor of Natural Resource Ecology and Management.
Deadheading!
David Hillock
“Deadheading” is a term often heard amidst the conversations of gardeners across the country. One not familiar with the term may be somewhat startled by such a word. However, it simply means to remove old, faded, spent blooms from your plants by pinching or cutting them off. By deadheading your flowers, new blooms are encouraged, and the blooming period of many plants can often be extended.
Remove old blossoms by cutting or pinching back to just above a leaf node on the stem below the flower. If the stem of the plant is somewhat woody and tough, then pruners or a pair of sharp scissors may be used. Soft herbaceous plants can be pinched by hand. When I worked as a gardener in Utah, we used a good old pair of sharp sheep sheers to cut back the hundreds of petunias and other annual flowers we were growing. Petunias respond well to a good haircut about early to mid-July. Many of the newer varieties of annuals on the market are self-dead-heading and may not need trimming. But, if necessary, cut them back about one-third to half-way, give them a shot of fertilizer and watch them bloom like crazy the rest of the summer. Other plants that respond well to deadheading include ageratum, geranium, marigold, and zinnia. Many perennials can also be enjoyed longer by deadheading, which can extend their bloom period.
Reclaiming Property from Moles
David Hillock
Moles are hairless, beady-eyed, web-footed animals about four to seven inches long that leave visible tunnels running just under the soil.
Moles prefer loose, moist soil full of grubs and earthworms, which can be problematic for landowners and gardeners.
Moles are extremely beneficial animals as they remove many damaging insects and grubs from lawns and gardens, as well as aerate the soil. However, their burrowing habits can disfigure lawns and parks, loosen the soil around shallow rooted plants and create havoc in small garden plots.
For small areas, such as flowerbeds or small gardens, a metal or hardware cloth fence should be installed and buried to a depth of at least one foot and bent out at a 90-degree angle. This will not be practical for large areas.
There are many techniques to rid the property of moles, including scaring them away with vibrational devices, using chemical products or toxic baits and using fumigants. Most of these are not highly effective. The most successful and practical method of getting rid of moles is trapping. Traps are well suited to moles because the mole springs them when following its instinct to reopen obstructed passageways. Success or failure in the use of these devices depends largely on the operator’s knowledge of the mole’s habits and of the trap mechanism.
A popular style of mole trap is the harpoon or impaling-type trap. This style has sharp spikes that impale the mole when the spring-loaded spikes are driven into the ground.
Select a place in the surface runway where there is evidence of fresh mole activity and where the burrow runs in a straight line. Dig out a portion of the burrow, locate the tunnel and replace the soil, packing it firmly where the trigger pan will rest.
Once the location is determined, the trap is set by raising the spring, setting the safety catch and pushing the supporting spikes into the ground, one on either side of the runway. The trigger pan should just touch the earth where the soil is packed down.
Release the safety catch and allow the impaling spike to be forced into the ground, which will allow the spike to penetrate the burrow when the trap is sprung by the mole later. Now the trap is set and should not be disturbed. Also, there should be no disturbance to any other portion of the mole’s runway.
If a trap fails to catch a mole after two days, it can mean the mole has changed its habits, the runway was disturbed too much, the trap was improperly set, or it was detected by the mole. In any event, move the trap to a new location and try again.
Moles are very important animals and should only be trapped when they are creating a significant problem. Their benefits far outweigh the damage they cause under most circumstances.
Also, verify that moles are the cause of your damage and not gophers, which create conical shaped mounds rather than long visible runways in the lawn. Gophers are typically found in sandy soils.
Why Aren't My Plants Blooming?
David Hillock
This is a common question received in our offices. When plants are selected for their flowering habit, it’s frustrating when they fail to bloom. It is often difficult to pinpoint the exact cause of a plant’s failure to bloom but here are some possibilities.
The plant may be in a location that is too shady. Full-sun plants need at least six hours of continuous sunlight to develop blooms.
There may be excessive competition from adjacent shrubs or tree roots. Too much competition from nearby plants may stress other plants to the point that flowering is limited.
Planting too deep may prevent flower buds from setting. A good example of this is peonies. Peonies won’t bloom properly if the crown of the plant is set too deep in the soil. The crown of the plant should be right at the soil surface.
Pruning at the wrong time of year could be a factor. Spring-flowering plants such as lilacs, forsythia, and azaleas produce their flower buds during the summer months and open the following spring. If these plants are pruned in late summer through winter, the flower buds will be removed. For late-summer flowering plants such as butterfly bush, crapemyrtle, and chaste tree, a mid-summer pruning could remove their flower buds thus prevent flowering from occurring.
Excessive sucker growth (fast-growing, unwanted branches growing up from major limbs near the base of the trunk) might reduce or limit flowering.
Newly planted trees, shrubs, and perennials may not flower for a year or two after transplanting. They may need sufficient time to develop their root system before they will again set flower buds.
Some plant species must reach maturity before they bloom. For example, wisteria may not bloom until it is 7 to 10 years old. Knowing how a plant was propagated may take the guess work out of how old it is and whether you can expect it to bloom sooner rather than later. If the plant was started from seed, verses from cuttings or grafting of older wood, it will need to reach its maturity stage before it can bloom.
Low winter temperatures or late frost can kill flower buds. This can be a problem with plants that bloom on old wood (spring-bloomers), such as some hydrangeas.
Soil chemistry may be a factor. If nitrogen is not in balance with other nutrients, plants may produce excessive vegetative growth at the expense of flower development. A soil test can help determine if this may be contributing to the problem. If high nitrogen levels are detected, eliminate, or reduce nitrogen fertilizer applications for a while.
Golden Rain Tree, Koelreuteria paniculata
Casey Hentges, Associate Extension Specialist
Bailey Singleton, Extension Assistant
When we think about adding flowers into the garden we typically think about small herbaceous plants. However, mid-June we often get questions about the “yellow flowering trees” people see planted around in the landscape. This is the appropriately named Golden Rain Tree, Koelreuteria paniculata, which produces a striking abundance of yellow panicles that are about a foot long and cover the tree’s canopy. With so many flowers and our Oklahoma wind, as these flowers fade, they can resemble golden rain and even create a yellow carpet below the tree. After these flowers fade, paper seeds pods begin to develop that sort of look like tiny paper lanterns extending the season of interest for this tree as they start out a lime green color and dry to a tan color.
The Golden Rain Tree is a deciduous tree with a pinnately compound leaf. It has good open branches that form a round canopy without any pruning. At maturity it will reach about 30-40’ tall and wide.
It is often used as an urban landscape tree because of its aesthetic value and smaller stature, as well as due to its tolerance of clay soil, drought, high pH, and air pollution. It is hardy from zones 5-9 and has no major pest or disease concerns here in the U.S. because it was originally native to China, Korea, and Japan. However, it has been here in the U.S. for quite a while as it was first introduced in the 1700s. While this tree may work for some urban settings, a note of caution must also be stated because this tree can easily reseed in more open spaces. The Oklahoma Invasive Plant Council has the Golden Rain Tree on their watch list for disturbed areas in Southeastern Oklahoma, but they have been seen in other parts of the state as well.