The Gardening Guru

David Daehnke
Mahwah, New Jesrey 07430
Here to help the experienced as well
as the novice gardener.

The Gardening Guru's Organic Lawn Care Manual (part deux)


The other five macronutrients - phosphorous, potassium, calcium, magnesium and sulfur - don’t get as much attention as nitrogen, but they are just as important. If you have used a high-nitrogen fertilizer in the past, there may be an imbalance in the soil. The best thing you can do is have your soil tested for pH and nutrients. This will not only tell you if you have a deficiency, but will also tell you how much of each nutrient to add to you soil. Phosphorous Phosphorous works behind the scenes and in the soil. It helps seed to germinate and to establish itself quickly and strongly. For established turf it aids in root growth. Phosphorous is present in every plant cell, where it is used to transform other elements into energy. To maintain adequate supplies of phosphorous in the soil, you need to add only 1/2 pound per 1,000 square feet per year. That can be provided with 5 pounds of bone meal, or you can use fish emulsion, cottonseed meal, or milorganite. Potassium Potassium doesn’t show up in color, growth or density, but has been shown to “toughen” the turf. It makes grass more resistant to heat, cold, drought, disease and traffic. The normal rate per year is 1 to 2 pounds per 1,00 square feet. A good source of potassium is wood ash, but that is not something you can put on your lawn, considering you would need 10 to 20 pounds per 1,000 square feet. Calcium, Magnesium and Sulfur Calcium helps by improving the uptake of nitrogen and increasing the growth of root hairs. It is also necessary for cell division within the plant. You can provide calcium by applying dolomitic limestone, which will also supply Magnesium. Magnesium is a component of chlorophyll that plays an important part in photosynthesis and helps absorb phosphorous. Sulfur is a nutrient you shouldn’t have to worry about unless you have been using the high-nitrogen fertilizer. Sulfur improves the grass color, increases carbohydrate reserves, contribute to cold tolerance, protein synthesis and new growth. Powdery mildew is more prevalent when sulfur is low.

Micronutrients Iron Iron improves fall and winter color, enhances root development, reduces the effects of stress, and is essential for the formation of chlorophyll. Excessive phosphorous creates an iron deficiency. Milorganite is a good source of iron. Manganese Manganese activates the photosynthesis process. Soils that have a high pH (7.5 or above) are usually deficient in this. Zinc, Copper, Boron and Molybdenum These are needed in minute quantities and if not applied properly, can cause the lawn more harm than being deficient. Check the fertilizer bag to see if these are included.


When the soil pH raises higher than 7.5, it can lead to deficiencies in the above mentioned micronutrients. If it goes below 6.0, the availability of phosphorous is greatly reduced, and calcium and magnesium are depleted. Nutrient availability is best when the pH is between 6.0 to 7.0. At a higher or lower rate, microorganism activity slows or even stops, reducing the breakdown of organic matter and the consequential release of nitrogen, sulfur and other nutrients. You can put all the fertilizer on that you can, but it will never reach the grass plants To raise pH (Pounds of limestone needed per 1,000 SQ.FT. to raise pH to 6.5 in each soil type)

Soil pH Sand Loam Clay 4.5 50 135 195 5.0 40 105 155 5.5 30 80 110 6.0 15 40 55

To lower pH (Pounds of sulfur needed per 1,000 SQ.FT. to lower pH to 6.5 in two soil types)

Soil pH Sand Clay 8.5 45 70 8.0 30 45 7.5 10 20

Using a Spreader

Although you can spread fertilizer by the handful, it is much easier and more precise to use a spreader. There are two different types on the market; broadcast and drop spreaders. A drop spreader is the most precise spreader available. This can be a benefit because you are applying fertilizer to specific areas, but can be a problem if you are not precise in following the wheel pattern. I call this effect a “football field” effect, where there are stripes in the lawn greener than the ones next to them. A broadcast spreader is not a precise, but it is meant to overlap each pass. Most of these cover a 6 to 8 foot swath on each pass. The label on the fertilizer you use will tell you the settings for your specific spreader, or you can mark off an area 1,000 square feet, set your spreader to a certain number. Cover the area (one path each until covered), replace the leftover fertilizer into the bag and weigh the bag. This will give you the pounds per thousand SQ.FT. of fertilizer USED. Then go back to the calculation used previously to figure the pounds of nitrogen per 1,000 SQ.FT.


Mowing is the most important thing you can do to your lawn. It can be the most beneficial or the most harmful. If you are an average homeowner, you spend 40hours a year if not more behind your lawnmower. Chances are your technique falls under two categories; the cut it each week at the same time in the same way, or the I mow it when it starts looking like a Savannah and you start losing things and people in it. A rigid mowing schedule does not suit the grass at all. Saturday does not mean its time to cut the grass. Grass grows at different rates at different times per year. Several factors should influence your mowing decision; water, heat, fertilizer, disease, dormancy and seasonality. Properly done, mowing can kill weeds, cure diseases, save water and provide fertilizer. Spend a little time figuring out the best schedule for your mowing and you will save yourself a lot of work later on in the season. At different times during the year, you will have to raise or lower your cutting height. Sometimes you may have to cut twice per week, while at other times you will only mow twice a month. To understand lawn mowing, it helps to know how grass plants grow. Grasses are basal growing crops. That’s why you can cut off their tops without killing them. The growing point is at the crown of the plant, near the soil line. The tips of the blades are not the youngest, but are the oldest part of the blade. Cut them off and the new growth pushes up from the crown, not from the top.

The good and bad of mowing

When the mower cuts of those tips, the plant undergoes a lot of changes. Mowing is the violent, physical removal of living tissue, causing a severe shock to the plant itself. The shock is due to the reduction of the food available to the plant. Grass lives mostly on the food produced in the leaves rather than drawn up by the roots. The leaf areas are where the plant’s photosynthesis takes place. Cut those blades and you reduce the availability of the plant to produce food. The food manufactured by the leaves is used for topgrowth and root growth. The longer the topgrowth, the longer the root growth. If you cut your lawn short, your roots will only be by the surface area and not down deep where the nutrients and water are. When you cut more than 40% of the leaf surface, the roots stop growing all together. The closer you cut, the longer it takes for the roots to begin growing again. Also, every time you cut the grass (especially if the lawn mower blade is dull), you are creating ports of entry for diseases. Close cutting also allows the sunlight to penetrate the soil and dry out the soil while encouraging weed seeds to germinate. These are the bad things that happen when mowing. When properly done, mowing can thicken a lawn and make it more weed-resistant. Like every other plant, its main purpose is to set seed and reproduce. When you cut the lawn, you are interrupting this process by cutting the seed heads, and the plant responds by producing more plants asexually, by tillering. The result is a thicker lawn, and with a thicker lawn the weeds seeds cannot germinate and there is no room for them to grow. Cut your lawn at a higher height instead of a lower height, and cut more frequently than once a week.

Mowing heights (Here are the best mowing heights, in inches, by species. The mower deck should be raised in hot weather or shade, and lowered for the last mow of the year.)

Grass Type Cool Weather Hot Weather Last mow Kentucky Blue 3 4 3 Fine Fescue 1 1/2 2 1/2 1 Tall Fescue 2 1/2 4 2 Perennial Rye 1 1/2 2 1/2 1

A quick mowing guide

You may need a ruler at first, but you will soon be able to eyeball when your lawn needs to be cut. But until that time, mark a wooden stake at the normal cutting height, then another mark at 1/3. This way you can visually keep a check on your lawn height and never cut too much off at onetime.

A rotary mower blade can spin as fast as 130 mph, and can shatter the grass blades as much as cut them. This is why you need a good, sharp blade. On a golf course, blades are sharpened once a day. The homeowner should sharpen his blades once a month. What size lawnmower should you have? It depends on the size of your lawn. A 1 acre lawn mowed with an 18’ lawnmower would make 171 swaths and hike the average of 6.9 miles behind it (two hours 18minutes). A 21” mower would make 141 swaths and hike 5.7 miles in one hour and 54 minutes. The choice is up to you. Also mow the lengths of the lawn to cut back on the time it takes to turn the mower around.


Misunderstood, maligned, thatch is though of just like dandruff. They don’t know where it comes from but they know it is bad. Lets disprove the common myths about thatch. 1). Thatch is always bad in every shape and form - No one is ready to promote thatch, but a little is not bad at all. It may even be beneficial. As mentioned earlier, it returns nitrogen to the soil, and if less than1/2 thick, it can act as a mulch to hold moisture and reduce weeds. 2). Thatch is caused by grass clippings - Clippings are not the main ingredient of thatch, because they start breaking down and providing nitrogen within a week after cutting. Thatch is mainly made up of roots, stolons, and rhizomes. These plant parts are high in lignin, a fiber, which makes them slow to decompose. Also, fertilizers, insecticides, herbicides and fungicides can actually slow down the decomposition process. 3). Thatch can be prevented by raking or bagging the clippings after mowing - As stated above, thatch is made up of other materials than grass clippings. Removal of grass clippings can actually slow down the decomposition time by removing this quick decomposer.

How can you win the war of thatch? Worms are excellent thatch busters as well as aerators. They prefer a lawn free of chemicals and acid fertilizers, a pH of 6.25 to 7.5, and moderate amounts of nitrogen. Also microorganisms help break down thatch.

Bringing microorganisms back into your lawn

A commercial product called Ringer’s Lawn Restore actually contains microorganisms and this product works well in reducing thatch. Aerating your soil will help bring microorganisms back. A compacted soil leaves too little oxygen for microorganisms. There are bars that you can aerate your lawn with, or a good pair of golf shoes will do just as well. Once you have removed the thatch, keep up with cultural practices that keep thatch out; fertilize sparingly, mow lightly and often, and take care not to over water your lawn.

Water wisely

Try to picture 27,154 gallons of water, enough water to fill a 6 foot deep pool that measures 20 feet by 30 feet. A 1 acre plot of grass needs that much water in a thorough watering. Even a moderate 5,000 square foot lawn will consume 6,000 gallons of water. Now before you start totaling your water bill, there are a few things to consider. You don’t have to supply all of that water with a hose and sprinkler. A good part of that will be supplied through rain. If your soil has enough organic matter in it, it will help store the moisture once it receives it instead of puddling and running off (clay) or leaching through the soil(sand). This number also changes in the summer. Lawns naturally go into a dormancy period when extreme hot weather is present, but we have been instilled with the notion that our lawn must be green ALL season long instead of letting nature run its course. A dormant lawn will resume normal growth when the stress effecting it has subsided (either heat or cold). In many cases, over watering can do more harm than good. Again we place more emphasis on keeping up with the Jounces instead of doing what our lawn wants us to do. The more water a lawn gets early on in the season, the more water it will need later on. Continuous moisture in the Spring will only create lazy roots that will not grow down into the soil, but instead remain up at the surface. On the other hand, to little watering may not be helpful at all. A sprinkler left running 10 minutes in one spot will not have enough time to soak the soil and the water will evaporate, not even getting to the roots. The trick is to water in a way that encourages grass to grow deep roots, generally 6 to 18 inches deep. Now some grasses just won’t grow that deep, such as bentgrass, which has shallow roots. Also keep in mind that root length is in direct relationship with shoot height; you mow low, the roots remain shallow. It is also important to keep in mind what kind of soil you have. The soil will determine when you should water, and even the type of sprinkler you should use. At full saturation, clay soils hold up to 2 1/2” of moisture per foot of depth, and supply turf for almost 2 1/2 weeks without any rain. Loam can hold 1 1/2” of moisture per foot of depth, and sand can hold 3/4” of moisture. You should not water until the reservoir is almost dry.

How much do I water?

Remember the statistics from above. If you apply two inches of water, it would not be too much for a clay soil (2 1/2”), but for a sandy soil, which can only hold up to 3/4”, the 2” would be wasted. Infiltration rates (the amount of water that can be absorbed in one hour) has to be kept in mind along with the holding capacity. These two numbers will effect what sprinkler you use and for how long. If you have a clay soil with a sprinkler running at 1 inch per hour, only 0.1 inch will be absorbed and the rest will be run-off. Not a good deal for you or your lawn. Flow rates for sprinklers are normally printed on the side of the box it came in. What if your sprinkler puts out more water per hour than the soil can accept? Let’s say that your sprinkler puts out 0.6 inches per hour and you have a clay soil that will accept only 0.1 inches per hour. You should run the sprinkler 10 minutes on, 50 minutes off, and you won’t waste a drop. Infiltration rate of water

Texture Inches/hour Sandy 1.0 Sandy loam 0.5 Loam 0.25 Clay loam 0.15 Clay 0.1

The key to watering is to make sure the lawn receives 1” of water per week, including rainfall. It is that simple. When watering, do not water after 3 p.m. in the afternoon. Any moisture after this time can sit overnight and become a host for disease. Make sure the lawn dries out thoroughly before nightfall comes. Remember top water only when necessary, before nightfall, and when you water, water thoroughly.


You can have a good looking, virtually weed free lawn without the use of chemicals. You can have a good looking, virtually weed free lawn without the use of chemicals. Now that I have hypnotized you into believing this, you must understand the laws of the lawn. 1). What is a weed? A weed is, terminology wise, a plant that is out of place or in the wrong place. On a putting green at a golf course, Kentucky Bluegrass would be a weed, whereas on your home lawn, bentgrass is the weed. Society’s perception of a weed has changed over the years. Clover was soft to walk on, mows well, smothers other weeds as well as fixing nitrogen from the air. It was sold by the tons and mixed into lawns. It wasn’t until a company came along and said that clover didn’t fit into a “modern” lawn did it fall from grace. By the way, the company also sold a chemical that would kill the clover. What about dandelions? Are they weeds? Not to the kid blowing puffballs, or the old man making dandelion wine or the farmers in Vineland, New Jersey. They grow dandelions in neat little rows for their tasty greens that are sold up and down the east coast. On those farms, turfgrass is the weed. The most important question you can ask yourself is, “Can I stand a few weeds in my lawn?” As my father always told me, weeds stay green all summer long and your lawn looks green from the road, so they can’t be all that bad. If you must remove the weeds, do so with cultural methods, such as the dandelion fork. To keep future weeds out, the best defense is a healthy, thick lawn. If the lawn is thick and vigorous, there won’t be any room for the weeds to elbow their way in. Keeping your lawn 1/2” higher in the summer will not only keep the roots long, but will also shade out the newly emerging weeds. If you have a weedy lawn, good grass care will eventually force the weeds out, but this will take time. You can quicken this time by doing the elbow grease of pulling, chopping and cutting the weeds. This will not be as easy as spraying the lawn with herbicides, but there are plenty of reasons to avoid using chemicals. Chemicals are poisons, plain and simple. And as I have stated earlier, chemicals can slow down the biological processes that strengthen the grass plants, decompose thatch, and discourages diseases. There are several bad management practices that can lead to weeds; 1). You are growing the wrong type of grass for the area. 2). Your soil is compacted 3). Heavy use 4). Improper fertilization 5). Drought or improper watering habits 6). Mowing too closely 7). You shouldn’t grow grass in that area.

The following pages include pictures of the weeds you may encounter, and when to watch for them.


How would you feel if I told you that you could reduce the amount of crabgrass to nothing without work, chemicals or weeding? The University of Rhode Island has showed that higher mowing alone reduced crabgrass on their test plots to almost nothing over a five year period. They also found out that the non-chemical control worked better than the chemical control, even though it took time. The second study was done over 50 years ago by the Ohio Extension Service. It showed that a late season fertilizer (November) got the grass growing earlier which in turn crowded out the crabgrass. The third method is more drastic and should only be used on severely populated crabgrass areas. Cover the area with the black weed fabric that is available on the market today for ten days. The crabgrass will be dead when the fabric is removed, but the regular grass will be yellow and will recoup by two weeks


Again, as with weeds, bugs very rarely trouble a healthy lawn. The first step in natural insect control is learning not to over-react and nuke the entire lawn for a half a dozen bugs. The point is to attack only when they are actually doing damage to your lawn in a widespread way. The second step is to provide a habitat that is beneficial to grub eating birds and beneficial insects. Birds just need a water source, cover, and food during lean months to become your best friends and the bugs worst enemy. Beneficial insects feed on the nectar from several plants, including Queen Anne’s Lace, coriander, dill, fennel, black-eyed Susan, sunflowers and yarrows. Now you don’t have to plant these in your lawn...beneficial insects cover a 50 yard area from these plants, so you can incorporate them into your landscape plantings. I could have a seven night course just on bug problems and how to identify them, but hopefully the cultural practice I have told you will keep these critters away. Enclosed you will find examples with the damage associated with each. Most garden centers will have the “Ortho Problem Solver”, a great resource when identifying the damage and insect. Use’s free!


You awake one morning to find that a patch of your lawn has turned brown. By the time you get home from work, the patch has doubled in size. The next day there are literally hundreds of patches engulfing your lawn. What do you do? Grab a fungicide? Make an emergency call to a lawn care company? Panic? To most of us, lawn diseases are mysterious and since we know little about them, they frighten us. Many factors can trigger a disease outbreak in your lawn: poor cultural practices, too much water, not enough water, too much fertilizer, not enough fertilizer, inadequate lime, soil compaction, poor mowing habits, and surprisingly enough, too many pesticides and chemicals. If you do have a problem, good cultural practices can help eliminates the diseases. In fact, a lawn that is pampered will be the first to get a disease. Diseases are a sign that something is wrong with your lawn. There is a triangle of plant pathology that is needed for a disease to become a problem. 1). There is the disease agent itself, and for a lawn it is a fungus. 2). There is a host plant that is susceptible to the disease. 3). Conditions must favor the development of the disease.

If any of these “legs” are not present, the disease cannot occur. We will now look at each leg and how to break the triangle to prevent a disease infestation.

Disease Agents

All major turf diseases are caused by fungi, and these fungi are always present in our lawns. The chemical approach would be to nuke the fungus, but the fungus will never disappear. There are about 100 different disease causing fungus, and in a normal lawn you will find at least 5 if not more. In a healthy lawn, the disease pathogens are outnumbered by the nonpathogenic microfauna and microflora (amoebas, nematodes, insects, bacteria, actinomycetes, and fungi) that the good will out compete the bad for food. This means they have the upper hand and keep the disease causing organisms in check. Stress, caused by poor cultural habits, can give the disease organisms an upper hand and they will run rampant. In time if the stress is reduced, the soil will reestablish the equilibrium and the disease will disappear. The common approach today is to grab the fungicide and knock it back quickly. This may work for the short term, but in the long term you may make the problem worse. The fungicide will not only kill the bad, but also the good fungus. The results can be further outbreaks of diseases. If you continue to use fungicides, the fungus will become resistant to the fungicide and it will continue to spread. There have been studies that show turfgrass diseases have been made worse from fungicides than better. Rusts, leaf spot, red thread, typhia and pythium all have been made worse from an application of benomyl. On the other hand, Michigan State University researchers have found that commercial organic fertilizers could help lawns and also reduce thatch, which is a major contributor to the disease cycle. As strange as this may sound, if you can find a liquid seaweed extract to apply with a hose end sprayer, there is a hormone in seaweed that naturally prevents diseases, and also fertilizes as well.

Grass Hosts

With the newer, more disease resistant varieties of grasses on the market today, lawn turf isn’t a gracious host to diseases as it once was. All told, there are over 200 varieties of grasses that are resistant to one or more diseases. Remember, the first step is to plant the right grass in the right place. A grass that is in the wrong local will be stressed and susceptible to attack.


The third leg of the disease triangle is the conditions that favor the growth of the fungus. You are limited to the things you can changes, which are few and far between. Mostly you can’t change humidity or stop the rain, but you can make sure your lawn is the healthiest and most resistant when those conditions are favorable. The more maintenance spent on a lawn usually means the more susceptible it is. There are several reasons for this. 1). Excessive nitrogen force the grass plant to grow too quickly, making it easy for certain diseases to strike. Overfertilizing also discourages earthworms and other microorganisms, which in turn increases thatch and the diseases that harbor there. 2). Acid fertilizers, such as ammonium sulfate, found in most common fertilizers, favor the fungi in the soil while discouraging bacteria and actinomycetes, both fungus fighters. 3). Excessive watering a foliar feeding soften the roots system. They are not strong, healthy and deep. 4). Lawn herbicides actually increases rusts and fusarium disease in you lawn. 5). Frequent low mowing stresses the grass plants and makes them susceptible to disease.

How to be a disease detective

To diagnose a disease or to get help from your local Garden Center, you’ll have to be able to answer these questions.

1). What species of grass is affected? 2). When did the problem first appear? 3). What were the temperature in the day and night when it first appeared? 4). Has the weather been exceptionally wet or dry? 5). What were the first symptoms? 6). Has the symptoms changed? 7). Has the affected area grown larger or changed shape? 8). Do the grass leaves show lesions, stripes or patterns? 9). Was the lawn watered recently? 10). Is the area sun or shade? 11). Has anything spilled in the area?

The following list is here to help you diagnose your lawn problem. Always consult a professional if you are undecided.

Diseases by Seasons

Spring; Necrotic leaf spot, pink patch, red thread Early Summer; Brown patch, fusarium blight, stripe smut Late Summer; Brown patch, dollar spot, powdery mildew, pythium, rusts, stripe smut Fall; Fusarium patch, necrotic ring spot, pink patch, red thread

Preferred Conditions for Disease

Cool Weather (below 60 degrees); fusarium patch, powdery mildew, red thread, slime mold, smuts, drechslera leaf spot Warm Weather (60 to 80 degrees); dollar spot, necrotic leaf spot, red thread Hot Weather (80 degrees +); brown patch, fusarium blight, pythium, rusts Dry Weather; dollar spot, drechslera leaf spot, melting out, red thread, rusts Wet Weather; brown patch (hot and humid), fairy ring, leaf spot, melting out (cool), pythium, red thread, slime mold, stripe smut High Nitrogen Levels; brown patch, drechslera, fusarium blight, fusarium patch, powdery mildew, pythium Low pH; dollar spot, stripe smut Shade; powdery mildew, pythium Low Mowing; drechslera, fusarium blight, necrotic ring spot Thatch; Fusarium blight, fusarium patch, leaf spot, slime mold, stripe smut

Disease Pattern Shapes Circle; brown patch, snow mold Irregular; pythium, slime mold Patch; red thread Ring; fairy ring Spot; dollar spot, fusarium blight, necrotic ring spot, stripe smut Unpatterned; drechslera, powdery mildew, rusts

Disease Color

Green; fairy ring Pale Green; fusarium blight, smuts Pink; red thread Red; drechslera Red to Tan; fusarium blight, rusts Tan; brown patch, dollar spot, drechslera, fusarium patch White; powdery mildew White and Black; Slime mold Yellow; fusarium patch

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