Questions

Ashes — July/August 2011

Q. Can I use the ashes from my wood stove in the garden or in my compost?
— Jane Marshall, Monroe

A. Wood ash is a desirable soil amendment if used in the right amounts. Wood ash supplies calcium, potassium and many microelements. The greatest concern is overuse.

Because wood ash is considerably more alkaline than limestone, overuse can raise soil pH to unacceptable levels. Thus, wood ash should be considered similar to limestone in its use (although less is needed to raise the pH) and soil tests for pH should be performed regularly to make sure your soil pH is not excessive.

Typically 20 pounds of wood ash (equal to a 5-gallon pail) per 1,000 square feet of garden or lawn per year is suggested.

— Gregory J. Bugbee, Soil Scientist, CT Agricultural Experiment Station, New Haven, (203) 974-8512, Gregory.Bugbee@ct.gov

Coffee Grounds — July/August 2011

Q. Is it a good idea to put spent coffee grounds in the soil? My soil is kind of clayey. If so, why?
— Priscilla Kissick, Branford

A. Spent coffee grounds can be used in moderation in the garden. Coffee grounds are organic and contain approximately 1.45% nitrogen. They also contain magnesium, calcium, potassium, and other trace minerals.

Some claim that the caffeine makes plants grow faster but this is unproven.

Coffee grounds can be sprinkled on the soil surface at a rate of 10-20 per 1,000 square feet. When preparing a garden, an inch or two can be worked into the surface 6 inches of soil. This will help loosen up clayey soil.

Again, routine soil tests are suggested to make sure you soil pH, etc., is in the right range.

— Gregory J. Bugbee, Soil Scientist, CT Agricultural Experiment Station, New Haven, (203) 974-8512, Gregory.Bugbee@ct.gov

Lawn Cutting Height — July/August 2011

Q. At what height should I cut my lawn?

A. Mowing height depends on the type of turf you have and the time of year.

The following advice assumes a typical mix of cool-season grasses such as Kentucky Bluegrass, Fescue and perennial Ryegrass.

In the spring, make your first cut at 2 inches and throw away the clippings in case there are any overwintering fungii.

As spring turns to summer, gradually increase the cutting height. When summer heat/drought arrives, you should be cutting your lawn at 3 inches or higher.

As fall approaches, gradually reduce cutting height back down toward 2 inches. This is particularly important if you're going to do any fall seeding.

Some grasses, such as Bent grass and Zoysia, can be cut lower than 2 inches in the spring and fall but always let your grass grow longer during periods of mid-summer heat or drought.

Make sure your mower blades are SHARP. Lawns can be severely damaged, even ruined, by being shredded by a dull or improperly adjusted mower. Rotary blades should be sharpened and balanced frequently. Make your job easier, prolong mower life, and keep your lawn happier.

Cut often enough so that you do not cut off more than one-third of the grass blade at a time. If your lawn has become very long due to long periods of rain, like this year, cut higher first, then re-cut three to four days later, until the height is back to normal. You can kill your lawn by scalping it. Besides, it looks terrible! Brown is a funny color for grass.

Try to leave the clippings, if they aren't bunching up in clumps which can smother the grass. This will return nutrients and organic matter to the soil. [Editor's Note: Over the course of a year, the nutrients provided by the clippings are equal to one fertilizer application.]

If you cut wet grass, it will not cut easily or distribute the clippings. Wet clippings tend to bunch together, requiring raking. So try to cut when your lawn is dry.

Cut at different angles each week and don't cut wilted grass because it can cause serious harm. If possible, water your lawn after cutting.

— Todd Harrington, Harrington's Organic Land Care, Bloomfield

Crabgrass & Grubs — March/April 2011

Q. My lawn is wrought with crabgrass and ruin from grubs. Do I treat these things chemically or plant new grass first?
— Susan Ewart, Harwinton

A. The damage has already been done. Applying chemicals is not only a waste of time and money but also a potential source of pollution that could affect your well and your health.

Better to start over and the best time of year to do that would be early fall, because you don't have the summer insects and weeds to deal with plus there is less chance of a drought. Our cool season grasses (blue rye and fescues) grow and develop best in the cool weather, not in the middle of the summer.

If there's a history of crabgrass I would seriously think about getting chemical and biological soil tests done. We find that if pH values are in the high 6 range or close to 7, and the base saturation of calcium is above 68%, there is less chance of crabgrass growing well.

After getting your soil tested you should apply a half-inch of finished compost to the areas in question and reseed. Most likely these areas are in full sun and, if there is no irrigation available, I would reseed with a 90% turf type tall fescue and 10% blue rye mix. Turf type tall fescue is a bunch grass but has a thicker blade that helps shade out the crabgrass in the spring and has allelopathic properties that inhibit the growth of certain other species. If the clippings are left, that will also help reduce crabgrass.

The good news is there is an organic product called Corn Gluten Meal (CGM) that can be applied in the spring that helps suppress crabgrass and some other weeds. It also makes an excellent spring fertilizer.

OK, now for the bad news. About every 5 or 6 yards we visit, the homeowner has applied corn gluten meal the previous fall and is puzzled as to why he/she has so many weeds. A common comment is, "I think I caused a bigger weed problem. Look, I have more weeds than my neighbor and they didn't apply anything." The sad thing is, I know exactly how they feel.

Harrington's used CGM for more than 10 years trying to get it to work. We always thought our timing was off, or it was not good product, so we would change suppliers, but every year we had people wondering why their weeds were so bad. The reality is they are absolutely right; they did cause a larger problem when they applied corn gluten meal in the fall or too late in the spring.

Why? To answer that we have to understand how corn gluten works. Dr. Nick Christians at Iowa State University (ISU) discovered the pre-emergent qualities of CGM and later Dianna Liu, as a graduate student at ISU, eventually isolated the five individual dipeptides (combinations of two amino acids) that had the ability to inhibit root formation of germinating seedlings. It is important that we understand that CGM does not inhibit germination. It inhibits root formation.

For CGM applications to be successful, it must be applied 2 to 3 weeks before seed germination, watered in sufficiently and then all irrigation shut off to allow the soil to dry out. This allows seeds to germinate and allows time for desiccation before the next rain/water occurrence. If the soil is moist after the point when the CGM's effectiveness is degraded then the weed seedling will produce roots and will "grow out" of the CGM. If this scenario occurs then the weed seed will have the benefit of the CGM's "9" nitrogen (N=9 in N-P-K), allowing it to grow faster, taller and stronger than if nothing was applied.

The fall/winter application of CGM, in my opinion, is not a good horticultural decision and does not provide effective weed suppression. It is not a good horticultural practice because 20 lbs. of CGM per 1,000 sq. ft. is the equivalent of 2 lbs. of nitrogen at a time when plants are naturally going dormant. That amount of nitrogen will stimulate freeze-prone tender growth instead of allowing the plant to harden-off for the winter. Also, high nitrogen applications increase the chance of our cool-season grasses succumbing to fungal diseases, such as brown patch and snow mold. When you add on the challenge of needing a dry period to allow for the desiccation of the weeds, then chances are CGM is not going to deliver as advertised.

When should corn gluten meal be used? The only time I would recommend using CGM would be in the spring as the grass is greening up. This application supplies the grass a shot of nitrogen so that it greens up quickly, increasing its density and height so that it can physically out-compete the weeds. Physical competition is the most effective weed-suppressing tool. Any weed suppression the CGM offers is a bonus and thus not a waste of money or labor. I still have a "but" to inject here. CGM is composed mostly of nitrogen, containing little or no phosphorus or potassium. This makes CGM a very "white bread" sort of diet for the plants. It's not a well-balanced product that feeds the soil and plant in a holistic manner.

— Todd Harrington, Harrington's Organic Land Care, Bloomfield

Controls for Grubs Other Than Corn Gluten & Milky Spore — March/April 2011

Q. Are there effective controls for crabgrass and white grubs other than corn gluten and milky spore?
— Diana Byrne, Clinton

A. See crabgrass control above!

When it comes to grubs it's been totally hit or miss with the milky spore and beneficial nematodes. Let's talk a little about the entomopathogenic nematodes (EPNs), tiny roundworms that can deliver pathogenic bacteria to certain kinds of insects. The nematodes either actively seek out the insect or lie in "ambush," waiting for an insect to pass nearby (depending on the nematode species). There are several species of nematodes currently available commercially but they tend to be fairly specific as to the kinds of insects they attack.

Several people have asked me recently about nematodes. The two most frequently asked questions are: 1) Which species is most effective against white grubs? and 2) When should I apply the nematodes?

Which nematode is most effective against white grubs? Based on information from colleagues of mine in other states, the most effective species of nematodes against white grubs that is readily available is Heterorhabditis bacteriophora (Hb). We have conducted trials in previous years that achieved acceptable levels of control with Hb nematodes against Japanese beetles, Oriental beetles, and European chafers. However, we were able to do everything "just right" -- time the application when grubs were present and most susceptible, and water in very thoroughly.

Dr. Albrecht Koppenhofer, a turf entomologist at Rutgers University, probably knows more about nematodes and their interactions with white grubs than anyone else in the United States. He tells me that he has a very different experience -- that Hb works quite well against Japanese beetle grubs but not the other species. He has also tested other species of nematodes and some show promise, but most are limited in their availability. He also discovered a new species of nematode, Steinernema scarabaei, which show tremendous potential against many species of white grubs, including all the ones that are problematic in New England. But that nematode has proven difficult to produce in large volumes. Dr. Koppenhofer's field and laboratory trials with S. scarabaei have demonstrated the effectiveness of that nematode. (In fact, it appears that a single application may last for more than one season in some parts of New Jersey.) But because of the production issues, it will be a while before we see that nematode available on the market.

So, for now, the best bet regarding nematodes on white grubs appears to be Hb. Keep in mind that the New Jersey research indicates Hb may be marginal in its effectiveness against grubs other than Japanese beetles. If you are able to optimize the timing of application and follow with adequate water, you certainly increase the likelihood of success.

What is the best time to apply nematodes to control white grubs?

The challenge in using nematodes to control white grubs is that the nematodes are endoparasitic. They need to be able to penetrate through the grub, so the grub needs to be large enough for the nematode to enter. White grubs have "sieve plates" on their spiracles, which provide a level of protection. In addition, grubs can often sense nematodes and spend time "grooming" trying to prevent nematodes from entering through the mouth. Finally, if you delay application until grubs are already in the third, and largest, developmental stage or instar, nematodes may not be effective. So, ordinarily you want to make the application when most of the larvae have hatched out of the eggs and are first instars or very early second instars. For some of you in southeastern Massachusetts, that may be the first or second week of August. For those of you further north, you may need to give the grubs a chance to finish hatching, and your timing may be a week or two later. There are few, if any, other organic or non-chemical based methods on the market to manage white grubs. We are in the early stages of testing a new product this fall with a manufacturer that we should have available this spring. It's a pure 10% Neem powder that has worked extremely well in our field trials. We hope to have a granular form of this product that homeowners can apply with their spreaders available for sale this spring.

— Todd Harrington, Harrington's Organic Land Care, Bloomfield

Are Corn Gluten Fertilizers Better Than Chemical-Based Fertilizers? — March/April 2011

Q. Are corn gluten-based fertilizers an effective way to improve lawn and soil over chemical-based?
— Paul & Susan Salisbury, East Haven

A. Absolutely a better choice over a chemical-based fertilizers because not only does it prevent some weeds from developing in the spring, but also does a really nice job at greening up the turf because of its high nitrogen value, which runs between 9-10% with most manufacturers. CGM is also a food source for many of the beneficial organisms in the soil where the chemical-based products can be detrimental to the soil's beneficial biology. But, even with some organic products like CGM, there can be pitfalls. Honestly, I am not a complete fan of corn gluten meal because it's a by-product of the corn syrup industry and is sold as an animal feed commodity, so the price is always higher than products that are waste products that should be used as fertilizers. I think CGM was born out of advertising hype and a need for an organic weed control. My hope is that we will soon have effective tools that stand up to field trials and not just laboratory studies. Maybe ISU will be able to isolate the effective portions of CGM and create a stable organic weed preventative that has longevity in the field.

— Todd Harrington, Harrington's Organic Land Care, Bloomfield

Weed Control in Garden Walkways — March/April 2010

Q. I manage a community garden with granite dust pathways between raised beds. Weeds are out of control, gardeners are elderly. Any suggestions? Hand pulling too difficult; management nix on flamethrowers, I don't want Roundup® anywhere near the place!
— Susan Watson, Bloomfield

A. Several organic tactics and strategies are available to you. In all cases, it is most effective to control newly emerging weeds when they are most vulnerable. Frequent monitoring and hoeing when seedlings are less than an inch high saves hours and hours of weeding later on.

Organic Herbicides

I have used two organic weed control products with success. Nature's Avenger® contains a citrus extract and can be applied to walkways. Burnout II, made by St. Gabriel Organics, is based on citric acid and clove oil. Both of these may need to be reapplied to older, more established weeds in the pathway. And, most importantly, avoid drift into your planting beds!

Physical Barriers

Physical barriers such as black plastic and typar can be placed under the gravel in your pathways. These preclude light and will eventually smother out weeds. Layers of newspapers or cardboard will also work. They will eventually break down and are available for free. Most ink used in newspaper these days is soy-based and safe, but I still try to avoid colored or wax paper or cardboard with glue. A thin layer of mulch, hay or straw could also be used to cover these physical barriers to camouflage their less aesthetic aspects.

Wood Chips

Fresh (uncomposted) wood chips can also be used as weed control in walkways. They have an extremely high carbon to nitrogen ratio. As micro-organisms break down the carbon, they will seek out and rob nitrogen from the leaves, roots and soil beneath them, knocking down any plants in their way. Eventually, the chips will compost and return these nutrients to the soil. But, in the meantime, keep them off your garden plots.

— Nancy Ballek Mackinnon, Ballek's Garden Center, East Haddam