Digital Editions

What is the proper way to fertilize bulbs with granular organic fertilizer? If I sprinkle it on top of the soil as the bulbs are emerging in the spring, does the fertilizer ever work its way down to the roots? If so, how long until it reaches them?

Spring-blooming bulbs, though dormant throughout the summer months, will have a semi-awakening in the fall and commence root growth until the ground freezes. On some, like the grape hyacinth, you may even get leaves; this of course makes it easier to find the bulb patch. So, as the days cool off in the fall, this would be a good time for your first light application of fertilizer. A liquid bulb fertilizer may be used or a low nitrogen granular. The granular, however, will need to be lightly scratched into the soil and watered very well in order for the nutrients to reach the bulbs. This step allows you to skip an early spring application. Directly after bloom—when you’re removing the flower head and stems (making sure to leave the leaves until they are brown)—is the next time that you may want to fertilize your bulbs before they go back into their summer dormancy.

We have a vacation home in Central Michigan and were considering planting Amazoy zoysia grass plugs. The ground is very sandy soil and we have a lot of poplar trees on the property. Is this a good product for Michigan’s climate?

At first glance zoysia grass appears to be a pretty perfect turf plant, if you consider all of the advertising hype:

• Grows by spreading; no seeding necessary
• Winter hardy
• Requires minimal watering & mowing
• Perfect for play areas

All true statements. Unfortunately, for those of us in the North, you will need to add the fact that while your neighbors’ bluegrass/rye/fescue lawns are emerald green in the spring, you’ll still be looking out on your straw-colored yard waiting… and waiting… and… you get the point. Zoysia is a warm-season grass and won’t even begin to green up until the daytime temperatures are well into the 70’s and nighttime temperatures are above 40. Zoysia will also need full sun. Michigan summers are short enough as it is. Having a lawn that only greens up after the last frost and promptly browns out at the first frost doesn’t make it a highly recommended turf in our area.

I have a climbing hydrangea which is growing beautifully on a northwest facing wall. It has never bloomed, however, and I’m wondering if there is something I can do to encourage blooms? It shares a space with clematis, hydrangeas and hostas, which are all doing very well.

Climbing hydrangea (Hydrangea anomala subsp. petiolaris) is a true climbing vine that attaches itself to brick, stone, trees or just about anything and will, if not pruned, grow to 60 or 80 feet using its root-like holdfasts on the stems. When mature, this plant has four-season interest, with beautiful dark green, glossy leaves in spring, followed by flowers for several weeks in late June or July, and finally peeling and exfoliating shaggy bark in the winter.

This plant is hardy in southeastern Michigan, and your northwest exposure should be ideal. The growing conditions appear to be just fine since your other plants are flourishing. The encouragement you can provide will be to simply wait for this slow-to-mature plant to establish itself. Although you do not mention how long the plant has been in its present location, it may not have been there the three or four years necessary for it to start taking off. Climbing hydrangea does not like to be transplanted and is slow to grow the mature root system necessary for blooming. Patience will reward you.

I love spring-flowering bulbs, but I was wondering if violas are the only spring annuals for our area. For the period before our frost-free date, I would like to try something else for color that will fade out with the heat and need a summer replacement.

Violas and pansies, related but separate species, are the kings of cold-tolerant, early annuals. Violas are a more petite plant, producing smaller but abundant blooms. They also reseed, as evidenced by a long-time favorite, Johnny jump-ups. The cute purple and yellow blossoms pop up anywhere. Pansies are actually biennials or short-lived perennials in Michigan and have become the darlings of hybridizers for unusual color combinations. They mix well with the spring bulbs, such as daffodils, tulips and hyacinth varieties.

A few early, cold-tolerant annuals you might not have guessed are sweet alyssum, stock, snapdragons, dianthus, forget-me-nots, sweet peas, calendula, and lobelias. Start them in pots indoors or purchase hardened stock from your favorite greenhouse. Then nestle the sprouting pots in small clusters into the soil amongst your flowering bulbs. Surrounding them with soil protects and insulates their roots from freakish cold snaps. The refreshing color jazzes up the traditional spring bulb show and lends interest and texture to the overall display.

I have a three-year-old African violet that is watered and fertilized regularly, yet it has never flowered. It is in a west-facing window. How do I get this plant to bloom?

There are several reasons your African violet might not want to bloom. Let’s examine the “perfect” conditions for African violets and you can check them against what you are currently providing. The most important factors are light, pot size, soil, water and fertilizer.

Optimal light is the cooler morning sun from an east window with the plant located twelve inches or less away. They can take the hotter west window, just watch them for wilting or have a sheer curtain to block the hot summer and cold winter temperatures. They need 12 to 14 hours of bright, indirect light. An easy way to tell if your plant is getting enough light is to look at the leaves. If they reach for the light and have long upright stems, they need more. If they lay nice and flat on the pot they are happy. If you don’t have good windows, they grow easily under artificial “grow” lights with full spectrum bulbs placed 12 inches above the foliage for at least 12 hours a day (use a timer).

Temperatures should be between 70 and 75 degrees, although a cooler windowsill in hot (west or south) windows can work. Avoid drafty windows and doors or locations near heating and air conditioning vents.

African violets like to be consistently and evenly moist, but not wet. Watering from the bottom is a good technique, as is keeping the pot inside another pot. This insulates the plant from hot temperatures if it’s in a west window and allows it to wick up water from the deeper pot. Try to water with room temperature water and use fresh rain or spring water. Any water not absorbed by the soil within about 30 minutes should be poured out. If you water from the top, water carefully under the leaves and don’t splash the leaves. Too much water will lead to crown rot and too little will cause the leaves to wilt and invite pests.

African violets are heavy feeders (since they are shallow-rooted) and like fertilizers formulated especially for them. Most brands are recommended for use with every weekly watering. A fertilizer with a 12-36-14 formulation is good for bloom production (the middle number represents phosphorus, which is for healthy roots and blooms).

Small, tight pots, especially non-porous types like plastic and ceramic are best, but whatever you use must have a drainage hole. A plant with a 12-inch spread can be happy and bloom in a 4-inch pot (the rule of thumb is to use a pot with 1/3 to 1/2 the size of the plant spread). Make sure there is only one plant per pot. Sometimes African violets send out suckers; cut these off immediately.

A loose soil mixture with great drainage is essential to allow the small roots to penetrate. You should be able to easily push your finger into the soil.

Dry air is another possible reason your plant doesn’t bloom. They like 50 percent humidity. Place an open saucer of water next to the plant, or set the plant on a tray filled with pebbles and water. The pebbles keep the plant’s “feet” dry.

Removing spent blossoms (the entire stem) and dry or diseased leaves (carefully) will keep your plant happy. If you like a symmetrical plant you can remove a couple of outer leaves that ruin the circular appearance of the plant. Some experts say this also helps stimulate blooms.

Finally, according to the African Violet Society of America, if nothing else works, a bit of a shock can induce an African violet to bloom. They suggest tapping or squeezing the pot. Another way of shocking the plant is to withhold water until it wilts, then water. This is not advisable more than once because it can weaken the plant and invite pests.

I recently read that a 1 to 2 percent caffeine solution is a possible way to kill slugs. I know that coffee grounds themselves repel slugs, but what about the caffeine solution? How exactly does one make a caffeine solution of 1 to 2 percent?

The toxic effect of caffeine on slugs was inadvertently discovered by a biologist in Hawaii, Earl Campbell, now with the U.S. Fish and Wildlife Service, and Robert G. Hollingsworth, an entomologist with the U.S.D.A. Agricultural Research Service. Campbell was seeking a “silver bullet” solution to some tiny nonnative Caribbean frogs that hitched a ride on a ship and disembarked in the Hawaiian Islands.

These frogs are unbelievably noisy. Their mating calls go on all night and year-round, reaching 90 decibels. Note that OSHA requires workers to wear protective hearing devices at 85 decibels. So at this volume, sustained exposure to these irritating vocalists can produce irreversible hearing loss. Since the mid-1980’s, Hawaii’s alien frog populations have been rising exponentially, while the rest of the world populations are declining or becoming extinct. By sheer quantity and volume, the amphibians were now a health hazard and an ecological nightmare.

Campbell’s group began working through various off-the-shelf grocery products, trying to find a legal but readily available product to target the frogs. They found a caffeine-rich, anti-sleep preparation that worked at the product label’s recommended level. He got permission from the EPA to field test a dilute concentration of the compound on soil in greenhouses. As soon as Campbell anointed the soil with the caffeine solution, he unexpectedly discovered that slugs began surfacing and dying.

Hollingsworth became interested from a pest control perspective. Small snails chewing away at the roots ruin tropical ornamentals such as orchids. Hollingsworth tested various concentrations of dilute caffeine against the orchid snails. A 4-ounce solution of 2 percent caffeine devastated most of the garden slugs. Even a .01 percent solution killed a significant number.

The bottom line: caffeine makes a good botanical pesticide. According to Hollingsworth, the reason slugs and snails are so susceptible is that they have no exoskeleton to protect them from coming in contact with a water-based solvent. “The mucus, which is the basis for their locomotion, is very high in water content,” Hollingsworth noted, “and permits the water-soluble caffeine easy entry. Once inside the critters, the neurotoxin destabilizes the mollusks’ heart rate.”

Coffee tends to have a caffeine content of about 0.1 to .05 percent, so it should be somewhat effective at killing slugs in your garden. It won’t hurt to pour coffeepot leftovers on the soil around your hostas. Even the grounds lightly sprinkled over the soil surface will deter them and might also cause a toxic reaction. While it isn’t feasible at this time to make a 1 to 2 percent caffeine solution at home, anti-slug products containing this concentration might be made available in the future.

I want to start a rain garden in an area of my yard that sometimes is boggy but not always. The area is mostly sunny and the soil is sandy. I want plants that are native and not overly aggressive. Do you have any suggestions for a garden plan?

Polluted runoff is a big problem in urban areas where much of the ground is covered with hard surfaces such as roofs, streets, parking lots and sidewalks. Before development, rain and snow melt seeped slowly into the earth. Now water flows quickly across hard surfaces, picking up pollutants—from organic particles, pesticides, fertilizers, gas, oil and other types of residue—before dumping into storm drains.

Once in the storm sewer system, the water flows into local lakes and streams, thus polluting our water supply. Rain gardens are designed to direct polluted runoff into a low, vegetated area, where the pollutants can be captured and filtered.

The features of a rain garden aid in this biofiltration process: a shallow basin depth, gentle side slopes, soil that allows infiltration, and vegetation that traps sediment and sediment-polluting runoff. Vegetation shields the soil surface from raindrop impact while the root mass holds the soil particles in place. Improved water quality results from the nutrient removal process as the water and pollutants come into contact with roots and microbes in the soil. Plants, trees, and groundcover absorb up to 14 times more rainwater than a grass lawn.

The basic design components of a rain garden are a grass filter strip, a shallow surface water ponding area, a bioretention planting area, a planting soil zone, an underdrain system, and an overflow outlet structure.

A shallow ponding depth—approximately six inches—is preferred, underlain by two to four feet of depth for the planting soil zones. A strip of turf or groundcover at the top edge of the rain garden slows water as it flows into the garden and filters sediments. Water should infiltrate within 4 to 6 hours.

Ideally the soil is composed of a blend of 20 percent organic matter, 50 percent sandy soil, and 30 percent topsoil. This blend will naturally filter the rain as it runs into the rain garden. Some clay is desirable, because clay particles absorb heavy metals, hydrocarbons, and other pollutants. However, the clay content should not exceed 10 percent of the total. Clay soils hold water well, but high clay concentrations may cause poor drainage. Sandy soil permits water percolation, but very sandy soil is too permeable. If the soil is too sandy and will not hold water for any length of time, you may wish to add composted organic matter to the soil to increase moisture holding potential.

A soil pH of 5.5 to 6.5 is ideal for pollutant removal by microbial activity. A mulch layer on the garden surface aids in the decomposition of organic matter and helps to remove metals. It also helps to suppress weeds. Shredded hardwood mulch is best, because it resists flotation and has a greater surface area for binding metals in runoff. Soils in the landscape holding areas should not be compacted because this inhibits the water moving through the soil.

The way to make a rain garden, or any garden, appear “well kept” is to keep the edges tidy. Tall plants and grasses tend to flop over, so if you want a neat silhouette, you will want to stick with short species. Plants that can tolerate standing water and fluctuating water levels are typically planted in the center of the rain garden, while those at the outer edges grow in slightly drier conditions. Your local nursery can make recommendations as to what plants would be suitable for your needs. For more information on building a rain garden you can check out the website from Rain Gardens of West Michigan (www.raingardens.org).

A couple quick tips: Make sure that you locate downspout rain gardens at least ten feet away from the foundation of your house, so you don’t inadvertently direct water into your basement. Also, even if you are constructing a simple system with a rake and shovel, be aware of underground utility line locations.

When can I start putting a pre-emergent herbicide such as Preen on my garden beds?

There are two types of chemical weed controls: post-emergent and pre-emergent. Post-emergent herbicide kills weeds that are actively growing. A pre-emergent (Preen being one of these) prevents weed seeds from germinating, but does not kill existing weeds.

Pre-emergents work in the top 1 to 2 inches of the soil by creating a chemical barrier that prevents cell division in developing weed seeds. Different weeds germinate at different times of the year, and pre-emergents last anywhere from 3 to 6 months, depending on the brand you use and local conditions. The rate at which pre-emergents biodegrade in the soil and lose their effectiveness will depend on temperature, soil type, and moisture conditions of the soil. They will need to be reapplied more often in hot, humid conditions.

Depending on the brand, some pre-emergents are applied over the top of mulch, and some are applied to the soil before mulch is applied. To be effective for the spring season, apply pre-emergent in late winter or early spring, before the soil warms up.

While pre-emergents will not harm your plants if they come in contact with them for a short period of time, always wash or brush off stray granules from plant foliage to minimize damage or discoloration that could be caused by long-term direct contact with the chemical. Never use a pre-emergent herbicide in your vegetable garden, and be careful around areas where you intend to sow grass seed. If you spill a little in an area where you intend to plant grass, it will not grow.

The October 2006 “Tree Tips” column about oak tree problems discussed anthracnose and that a spring spray would help control that disease. What kind of spray would be best for my 2 very tall trees?

Since your trees are “very tall,” it is likely you cannot reach them while standing on the ground to prune or to spray. As such you need to call a professional. Also, the equipment used to help prevent anthracnose diseases in oaks requires the power of commercial grade hydraulic sprayers to propel the protectant.

Call a certified arborist who can examine your oak trees for problems, make an accurate diagnosis, and determine if they are in need of a preventive spring spray. A reputable arborist will be licensed by the state not only in tree knowledge but also in chemical application. They have the proper equipment and protective gear that are necessary when dealing with these products. They know the correct mixture and application regime to accomplish what is needed.

Is there an herb, or another low-growing plant, that I can plant to choke out mint and another unidentified spreading weed?

Before you can plant another low-growing plant to do battle with your mint and the ubiquitous “USW” (unidentified spreading weed), you need to weed out, with a spading fork and cultivator, the existing mint and weed root systems. Mint not only spreads through seed dispersal but also by sending out underground stems into the surrounding area, popping up a new plant where you least expect it. You simply can’t send in a new contender to the garden bed and hope it wins if the mint and USW are that well-established.

Your mission this season, if you decide to accept it, is to clean the invaded area of the noxious mint and USW, finding and removing as much of the roots as possible. If you had not done so last year, you might want to shear the mint carefully and dispose of spent flower heads. This will help prevent latent seeds from accidentally landing in the cleaned area as you remove the bulk of the plant.

A vigorous herb and low-growing plant to fill in the area would be any of the thyme varieties (Thymus). There are some wonderful lemon-scented and walkable cultivars now available. Depending on the size of the area, you could plant several varieties together, enjoying what each has to offer.

Since the mint is growing too well, the site is probably full sun and well-drained. Thyme loves those conditions as well. It will rot quickly in wet areas and suffer meltdown in hot, humid summers.

The next phase of your mission is vigilance. If you want the new pockets of thyme to thrive, you need to be on the lookout for mint and USW seedlings, pulling or cultivating them out before they can take hold and put down a root network. Look around your property, as well as your neighbors’ borders, for breeder plants that could be supplying seed for wind and animal dispersal. Taking a zero-tolerance approach this season to the former mint and USW area will give the thyme varieties a chance to establish themselves. They will cover the ground thoroughly, providing fragrance and flavor for your kitchen as well.