If you have an impossible time coming to grips with our weather this garden season, you have the best of company. The forecast so familiar to most Washingtonians -- "cloudy skies, with a good chance of showers today and tomorrow" -- has been repeated every weekend since late March. In between, there was a rainy Easter, a miserable Mother's Day, a wet and gloomy Memorial Day weekend, and showers the first weekend of June, albeit with tropical temperatures.
Meanwhile, the crises have been piling up. Depending on this weekend's weather and the extent of your landscape, this could be one of your busiest, catch-up gardening weekends of the year, and most of the chores are basic maintenance.
First, the lawn. If you have a sunny lawn, it's smart to apply Balan pre-emergent crabgrass control today or tomorrow, not only to continue total protection against crabgrass for the balance of the summer, but to control goosegrass, also known as silver crabgrass, on the lawn next month.
Goosegrass seed will germinate in the next 10 days, showing on the lawn the second weekend of July; from then on, it expands until it becomes an island of sorts, displacing good grass in the process. By late August, you could have so many dozens of "goosegrass islands" on the lawn that your only choice would be to kill everything with glyphosate, de-thatch and seed all over again. A Balan application this weekend eliminates that possibility.
If you have to cut the lawn, cut first, then apply the granular Balan. Follow spreader settings on the label. Leave the clippings behind for the next two mowings of the lawn after the Balan goes down.
Your second application of potassium sulfate (0-0-50) is targeted for the lawn this month at four pounds per 1,000 square feet. A spreader setting of 4 on the rotary Cyclone or Spyker spreader will apply the proper amount. Schedule your application so it rains shortly after the treatment, otherwise delay the application until rain is imminent.
Potassium sulfate relieves stress conditions so turfgrass is better able to withstand summer drought and scorching temperatures. University tests underscore the need for supplemental applications of potash apart from periodic fertilizer treatments. The product is available at most garden centers, nurseries, hardware stores and some building supply centers.
Over the past two weeks, yellow nutsedge has sprouted on sunny lawns, a problem that should not go uncontrolled. Nutsedge will spread throughout a lawn and landscape if not controlled, especially here in June, when it is easily stopped with Rockland's Super Crabgrass Killer (MSMA). Cut the lawn first, then apply MSMA; if your exterior water line from the house has an anti-backflow device, use the hose-end sprayer to control the nutsedge, otherwise the sprinkling can will do.
Let's clear up a crucial point about Super Crabgrass Killer. The label states to use one ounce in five gallons of water, applied to a 1,000-square-foot area. If the air temperature is below 90 degrees, use this rate, but if the temperature is 90 or above, you should use a half-ounce of MSMA to five gallons of water for the same coverage. The professional label (designed for golf course superintendents) always included this lower rate to avoid burning any good grass when the MSMA was applied to the lawn.
Apply MSMA as soon as possible as long as no rain is in the forecast. A week later, cut the lawn again, then make a second treatment. The nutsedge will be in limbo soon after, and no babies or seeds will be sprouting elsewhere on the lawn next June.
Sunny lawns traditionally go off-color in June. The reason is the sudden immobility of iron in the soil. In scorching soil temperatures, iron is no longer available to turfgrass roots. Because iron is needed, along with magnesium, for chlorophyll production, the grass turns pale green in color. Enter chelated iron and the lawn greens up soon enough. Applied to the lawn, chelated iron is absorbed by roots and foliage, after which it breaks down inside the plant to release its iron for optimum chlorophyll production.
Pick up a quart of Dexol's liquid iron about $8 and comes with its own hose-end applicator), which treats 5,000 square feet, or a gallon of liquid Ferromec for about $18, which will treat your lawn for the next decade or longer. Golf course superintendents have standardized on Ferromec for years, so it has multiple success stories to its credit. Apply either product over the next week, repeating in late July to retain good turfgrass color for the entire summer.
Pythium is the bane of over-watered, over-fertilized and over-managed June lawns. It happens when nighttime temperatures stay above 68 degrees and relative humidity hovers around 90 percent. Bingo, you have an outbreak of pythium disease, also called "grease spot" because of the greasy look of infected soil, and sometimes "cottony blight" because of the white cottony webs showing on infected blades of grass in the early morning hours. Usually, the webs show on blades on the perimeter of the infection, with dying and dead grass showing inside the circle.
Our one lawn management practice triggering pythium is over-watering. When the soil has its fill of water, disease spores in organic matter in the soil start flowing with the water, infecting healthy turfgrass wherever the water flows. If your lawn is on a slope and you find grass dying along the path that water takes from high to low ground, know that pythium has struck. Eventually, when water reaches the low point, it fans out in all directions, and pythium as well.
Two pythium cures are on the market: Aliette and Subdue 2E, both expensive fungicides by any standard. They are available only in water-soluble powders, not the granular formulation that one would expect for homeowner application. One application of either product is usually enough to erase pythium, providing you stop watering altogether and bag all future clippings. Washington's wet spring has predisposed a good many hardpan lawns to pythium, so beware!
With rhododendron, prune the withered flowers if you haven't done so already; if you don't prune, you could count next year's flowers on one hand. Here is how to prune:
Go down the remains of the flower, which looks like a miniature candelabra with seedpods at the top of the candles (actually, trusses). Go down the stem to the point where all the trusses come together, where you will find the start of new growth. In some cases, this growth is millimeters long, but a half-inch or more in others. Growth spots usually are opposite each other on the stem.
Using a sharp steak knife, cut through the stem a quarter-inch above the start of the new growth. In effect, this releases the "brake" on new growth for the rhododendron, and growth will resume almost immediately. Repeat this pruning to all stems showing withered flowers, even to those dried trusses from a year ago that were never pruned away. Surprisingly, growth will resume there once the old trusses are removed.
Mountain laurel is pruned in the same manner. Remove all withered blossoms this weekend to promote new growth. Laurel and rhododendron should be fertilized, initially with an application of Hollytone or F&B acid shrub plant food, perhaps with a light covering of compost or leaf mold, too.
If laurel or rhododendron leaves have turned pale green (enabling you to see the veins in the foliage), insert your electronic pH soil tester into the soil on the side nearest the foundation. If your test shows a pH between 5.5 and 6, a light application of iron sulfate, also known as ferrous sulfate, on that side of the plant is in order. If the pH is above 6, substantially more iron sulfate will be needed, probably a 12-ounce coffee can filled halfway.
Also, mix up a small amount of chelated iron in a hand-held sprayer, with spreader-sticker added, and apply to foliage in the evening when no rain is forecast. A few sprays will turn things around while the iron sulfate begins its job of reducing the soil pH over the next two months. Jack Eden is the host of "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM).