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Articles by Dr. Francis Gouin

Part 2: How to supply nutrients organically

     In organic gardening, all nutrients are supplied through the process of mineralization. As organic matter is decomposed by the microorganisms that digest the cellulose and hemi-cellulose, minerals contained within the cells of the animal or plant tissues are released into the soil. After the microorganisms have digested all digestible cells, they die. Since their bodies consist mostly of proteins, the proteins are broken down by enzymes, releasing more nutrients, mostly nitrogen (N), into the soil. 
    The rate of mineralization is dependent on temperatures in the soil.
    Under laboratory conditions, mineralization rates are measured at room temperature, 72 degrees. Moist soil samples are held in temperature-controlled containers for several days, then the amount of available nitrogen in the soil is measured. This process is repeated until the figures are stable. Mineralization rates are faster at temperatures above room temperature and significantly slower at temperatures below room temperature. At 72 degrees, the mineralization of compost is between eight and 10 percent. Mineralization of organic matter stops when soil temperatures approach the freezing point.
    The rate of mineralization has a major effect on plant growth.
    Because soils are cooler in the early spring, the rate of growth is often reduced for early spring crops such as peas, cabbage, broccoli, cauliflower, lettuce and spinach. Cooler soils mean fewer nutrients becoming available. This problem can be minimized by selecting south-facing slopes for early spring and late fall crops. Planting the crops on ridges is another method of encouraging early warming of soils. A soil raised above a natural grade warms faster than a soil that is level on grade. Covering the area to be planted with a sheet of clear polyethylene several weeks before planting, followed by ridging and covering the ridges with black plastic mulch, is labor intensive but will stimulate early mineralization. Soils warm very rapidly under clear plastic due to the greenhouse effect. However, anticipate early growth of spring weeds, requiring light cultivation or spraying with horticultural vinegar. Ridging and mulching with black plastic will also provide weed control.
    Apply no more than four cubic yards of compost or animal manure per 1,000 square feet in any one year. Five percent is one year’s limit for organic matter added to the soil. Excessive applications of either can stimulate excessive vegetative growth and weak spindly plants. With the mineralization rate eight to 10 percent, 90 to 92 percent of the minerals remain in the soil’s organic matter. So repeated applications of compost and organic matter should be based on soil test results.
    If existing soils contain less than three percent organic matter, an initial application of four cubic yards of compost or animal manure the first year followed by repeated applications at two cubic yards in successive years (or on alternate years for sandy soils) can be adequate. In silt or clay loam soils, these levels may be excessive, requiring greater dependency on soil test results.
    Initially, compost or animal manure should be incorporated to a depth of six to eight inches, deeper if possible. Because organic matter reduces the bulk density of soils, deep incorporation promotes deep rooting, making crops more tolerant to drought. As deep incorporation of organic matter promotes deep rooting, the roots that penetrate this region will continue to maintain the organic matter concentration in that region.
    Repeated applications of compost or animal manure should be incorporated only in the upper three inches of soil. This results in concentrating the nutrients in the region where seed germination occurs and where roots of new transplants initiate growth. Leaching will move nutrients deeper into the soil as the growing season progresses.

Lesson 1: From the ground up

     Organic gardening is a science based on being able to supply nutrient needs and ideal growing conditions that will produce healthy plants that can resist diseases and pests. Fruit and vegetables free of pesticides are considered healthier because they are untouched by man-made chemicals with the potential to cause health problems.
    Success in growing plants organically begins with selecting land that can generate ideal growing conditions. Site and soil are of utmost importance. Establishing an organic garden on a slight slope facing south gives you soil that warms more rapidly in the spring and stays warmer in the fall than soil on a northern slope. A warmer soil will release nutrients from organic soil matter faster. Sandy soil will warm faster than silt or clay soil because there is less water present and the soil is denser. However, during drought, sandy soils will need supplemental irrigation and/or mulch to satisfy the water needs of the plants.
    Full sun also helps warm the soil, enabling the release of nutrients from organic matter and maximizing ­photosynthesis.
    Well-drained soils are essential to promote deep rooting of plants and early warming of soils. Avoid poorly drained soils. Good air drainage is essential for the rapid drying of foliage to minimize disease problems.
    Since the organic content of the soil is the primary source of nutrients for plants, the pH measurement of soil acidity should be monitored by regular soil testing at three-to-five-year intervals. Soil testing is also a guide to maintaining optimum levels of nutrients such as calcium (Ca) and magnesium (Mg) and to prevent phosphorus (P) and manganese (Mn) from accumulating in excessive amounts.
    The organic garden thrives on organic matter. To be successful, you need to increase the organic matter of the soil to five percent and above. For every percent of organic matter present in soils, 10 pounds of nitrogen (N) is generated per acre per year through a biological process known as mineralization. To obtain optimum yield, you must maintain the organic matter content of the soil at between five and 10 percent. Maintaining levels of organic matter concentration above five percent requires yearly applications of organic matter. Good sources include compost, animal manure and organic fertilizers such as fish emulsion, cotton seed meal, bone meal and compost tea.
    In choosing seeds, the organic gardener seeks varieties with vigorous growth characteristics and disease resistance. In planting, avoid over-crowding, which increases competition among plants for sunlight and moisture. Crowded plants are more susceptible to diseases because they tend to be weak and their foliage is likely to remain wet for prolonged periods of time.
    Healthy plants are more resistant to diseases than weak plants. However, healthy plants are equally susceptible to insect damage, though they are better able to tolerate limited plant damage before significantly reducing yields.

Can the Bay Gardener solve it?

About 30 years ago, I began to build up my garden with compost and leaves. Every few years, I would gather and put down about three feet of leaves to rot and be tilled into the 50-by-50-foot garden space. The garden now has a beautiful loamy soil. I have been planting with wonderful results for about 20 years.
    About six years ago, I collected the leaves and put them down but did not plant for two years. I gather the bags of leaves, mostly oak, from neighboring houses. Several mulched bags of grass were in the mix this time.
    When I next planted my garden in a six-by-30-foot area, all the plants, tomatoes and cucumbers withered and died over a 12-hour period. The plants had been in the ground for about three weeks and had begun to produce small vegetables.
    I immediately removed them. The University of Maryland Extension Service recommended I plant buckwheat and oats. This I did for two years in a row. It grew beautifully, and so did the weeds.
    This year I have once again planted the garden. In the very same area, all the vegetables withered and died over 12 hours.
    The garden has been tilled many, many times. This is the only area that has the problem. It has not spread to another section of the garden.
    Could I have gotten some chemical like Roundup in the collected bags? If that is the case, why has it not moved with all the tilling?
    I might add that the dead plants have perfectly healthy root systems, and there are no tunnels or holes from moles or voles.
    I am totally at a loss as to what is happening and as to what I can do to fix the problem. Any advice you can give would be greatly appreciated.
–Pat Fessler, Crownsville

The Bay Gardener’s Solution


    The problem is not Roundup. Glyphosate, as the Monsanto weed-killer is called, deteriorates into phosphorus once it enters the soil. It does not have weed control properties when it becomes a soil component.
    I suspect that the soil is infested with fusarium, which is a fungus, or possibly sodium or soluble salts. I suggest that you have the soil tested by A&L Eastern Agricultural Laboratories. Request the S3 test to include soluble salts and sodium. Submit one sample of soil from the affected area and a second soil sample from the surrounding area. Do not indicate crop or request recommendations. Each soil sample should include at least five core samples from each area. Air-dry the samples overnight before mailing them for fast results. Print submission form and instructions from the web page: www.al-labs-eastern.com.
    Have the lab send me the results at DR.FRGouin@gmail.com. We’ll get to the bottom of this.

Rest and replenish your bed

If you were wise enough some years back to plant asparagus, you’ve been rewarded with a spring feast. Now it’s time to give your asparagus bed a rest to ensure future harvests.
    An asparagus bed planted in full sun in well-prepared and well-drained soil can remain productive for 20 years or more — if you treat it well.
    If you want your bed to serve you with an abundance of spears each spring, you must avoid over harvesting. Stop gathering spears by mid-June — now — to allow mature foliage to develop. An abundance of foliage is necessary to replenish the energy in the roots and crowns for next year’s crop.
    Extending the harvesting season until July will result in a limited crop next season because insufficient time was allowed for recovery. On the other hand, if you limiting the harvest to just a few weeks in the spring, the bed will expand too quickly, crowding the stems. This problem is corrected by extending the harvest season the following year.
    Weeds can be a severe problem in asparagus beds. Keeping up with weeds begins in the spring before the spears appear. Cultivate the beds lightly by using a Nebraska flat blade or a sharp hoe or by shallow tilling. I like to cultivate my asparagus bed the first week in April. We don’t start cutting asparagus spears until mid-April.
    Once the stalks have developed and the plants are in full foliage, an onion hoe is ideal for removing weeds. Soon after I make my final harvest in early June, I appliy Preen at the recommended rate. Preen is cleared for use on vegetable crops.
    Fertilize or mulch with compost soon after the harvest season. I apply calcium nitrate at the rate of one pound per 100 square feet and then apply a one-inch layer of compost. I also place a trickle irrigation line down the middle of each bed before applying the mulch. The trickle irrigation lines are on a feeder line of their own.
    In the fall, do not cut off the stems until the foliage has turned completely yellow. Patience allows all of the nitrogen in the stems to drain down to the crown, where it is readily available for next year’s crop.
    As asparagus beds age, they become more attractive to asparagus beetles. Thus far I have never had a severe infestation.
    However, in August you are likely to see caterpillars of different colors feasting on the foliage. These are mostly butterfly caterpillars that can most easily be picked by hand each day unless you are interested in promoting butterflies.


The Mystery of Bulb Storage, Solved

Q    I read your May 22 column (www.bayweekly.com/node/22306) on moving daffodil bulbs. It’s time to move mine, and your column is helpful. However, I have always wondered why you can’t just replant them right away. After all, they spend the summer in the ground if you don’t move them. But I’ve planted daffs right after I dug them, in June, and they didn’t do well at all. And these were my most vigorous growers. So why do they need to be stored until fall?
     –Lucy Goszkowski, Annapolis

A    Many bulbs are damaged in digging. Storing them before planting in the fall allows the wounds to callus. When bulbs are planted immediately after digging in the summer, damaged bulbs will rot. If you don’t mind gaps in your new planting, go ahead and replant the same day you dig.

Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.

Last winter was hard on this easy-to-grow fruit tree — but not fatal
The winter of 2013-2014 was so severe that it killed fig trees back to the ground. Many plants also suffered severe rabbit damage at the base of the young stems with smooth bark. Rabbits eat the smooth brown bark at times when other food sources are scarce.
 
As we are located at the northern climatic range for growing figs, we need to anticipate winter damage at least once every 10 to 15 years. According to my records, the last time fig plants were killed back to the ground was during the winter of 1997-1998.
 
If the stems and branches are not exhibiting new growth by early June, the tops of the plants have been killed. However, if you look closely at the ground beneath you should see new shoots emerging from the roots.
 
Cut the dead stems as close to the ground as possible and use them next winter for starting the fire in your fireplace or wood stove. Fig wood ignites very quickly and makes good kindling. 
 
Allow the new shoots to grow two to three feet tall before thinning. To avoid crowding, allow at least 3 feet of space between new stems. Select only the more vigorous stems to develop and prune out the unwanted ones. Do not simply break them away but use clean, sharp pruners to remove stems close to the roots. If you break the unwanted stems, you are likely to see additional sprouting that you will have to remove later.
 
This year’s new growth will not produce figs. If you do see figs developing in the axils of the leaves, rub them away with your hands. Allowing the fruit to develop on the new growth will weaken and dwarf the stem.
 
Allow the new stems to grow five to six feet tall before pruning away the tip of each. Tip pruning will stimulate multiple branching, which will provide more fruit for the coming years and prevent the stems from getting too tall. Preventing the stems of figs from growing above six feet facilitates harvesting. 
 
I have never fertilized my figs in the 20 years that I have been growing them here in Deale. Fertilizing figs makes them difficult to manage. If the summer foliage has a good dark green color, it is best not to fertilize them. The plants will tolerate a wide range of soils and are not sensitive to different soil pH.  
 
Figs are a fruit crop that I recommend to home gardeners because they require little attention and never need to be sprayed. Pruning to facilitate harvesting is all the attention they need. 
 
If rabbits are a problem there are several preventions. Surrounding the area with two-foot-tall chicken wire is the simplest if you have an extensive planting. If you only have a few plants, there are white plastic wraps that expand as the trunk grows. You can also solve the problem by loosely wrapping the trunks with two layers of chicken wire.
 
There are several varieties of figs offered by mail order nurseries.  I grow Brown Turkey (pictured) and Golden Egyptian. I have not seen any differences in hardiness between these two varieties.  Both were killed to the ground this winter.

Time your pruning for both desirable growth and flowers

While azaleas were blooming mid-month, I passed a home in the Deale area where the bushes were so large that it must have been impossible to look out through the lower part of the front windows. They must have been sheared at some point because the middle of the plants appeared very bushy.
    This is a common problem and one that is simple to correct — once you get out the pruners and get past fear. 
    Well-established azaleas are almost impossible to kill. Their only sure death is by over-mulching or repeated mulching with hardwood bark. The plants are very shallow-rooted; over-mulching them suffocates the roots. Repeated applications of hardwood bark lowers the acidity of the soil and releases high levels of manganese, which prevents iron from being absorbed by the roots.
    If azaleas are well established and growing too well, simply prune them back 12 to 18 inches below the windowsill now, as the flowers are wilting. The sooner you prune the better. Stems up to three-quarters-inch in diameter will sprout new branches by the hundreds. Do not prune all of the stems at the same height. Cut some stems back 12 inches, others 18 and others 24 to give the plant a more natural appearance.
    Within three weeks after pruning, you will see small green dots emerging from the bark. Each of those is a potential branch. If you allow all the green dots to develop, you will get too many branches, giving the plant a bottle brush appearance. To avoid this, in mid-June or early July, use your fingers to rub away half of the developing nubs. These newly emerging branches are soft, succulent and easily removed. In mid-August repeat the process, this time keeping the best-developed and strongest branches and removing the others.  
    Do not fertilize or mulch the plants with compost until after vigorous growth appears on the pruned stems. Keep them thoroughly irrigated during dry periods.
    Since azaleas initiate flower buds beginning in mid- to late September, avoid shearing the plants after the middle of August. Flower buds are initiated at the ends of newly developed branches. If you delay shearing until mid- to late September, you will be eliminating most of the new growth, and the plants will have no flowers next spring.

Plan to dig, separate, store and replant in fall

As years pass, clumps of daffodils, narcissus, jonquils and hyacinths become crowded, resulting in smaller flowers. Shrunken flowers mean it’s time to dig and replant. Wait until after all of the foliage has died back to the ground.  
    Mark the location and flower color of clumps to be divided before all the foliage is gone. Make a large plant label and stick it in the middle of the clump.
    Dig with a garden spade, starting at least six inches away from the outer circle of dead leaves.  Assume the bulbs are now deeper than the original planting depth: Bulbs are equipped with contractil roots that pull them deeper in the ground at the end of each growing season. This is a survival feature as bulbs originated in arid regions. Thus when digging bulbs that have been in the ground for a long time, you’ll have to go two to three inches deeper than the original planting depth so the bulbs can be lifted from the ground without damage.  
    After you’ve lifted the bulbs from the ground, shake away loose soil; do not separate the bulbs from each other until after the soil has dried.
    Then separate the clusters of bulbs from each other and thin them, allowing only two or three daughter bulblets to remain attached to each large bulb. Dust the bulbs with a fungicide such as a five-percent solution of Captan. Place them in an onion bag and hang in a cool, dry place to protect them from rodents.  
    In late September or early October, the bulbs will be ready for planting.  To avoid future overcrowding, dig the planting hole at least 10 inches deep and amend the soil in the bottom with compost. The top of the each bulb should be at least eight inches below the surface of the soil. The deeper bulbs are planted, the fewer daughter bulbs they will produce because there is less oxygen available. Less propagating means less crowding.


Stink Bug Report

    A report from the University of Maryland Department of Entomology indicates that research at Virginia Tech found colonies of stink bugs that wintered unprotected outdoors have been killed by severe cold temperatures. 
    If this is true, it will help considerably in reducing the population, but it will not exterminate them. Stink bugs that managed to overwinter in the cracks and crevasses of homes and heated buildings will persist.
    Based on the invasion we are experiencing at Upakrik Farm in Deale, the cold winter has not made a dent in the stink bug population. On warm days, they pour out of their winter hideaways.
    The pheromone traps I tested last fall never attracted a single stink bug.
    The only defense that has been 100 percent reliable in capturing stink bugs is the Bugzooka. This vacuum gun sucks them into the barrel without killing them and smearing their stinking guts on windows or woodwork. It is fun to use and gives you the feeling of sweet revenge. Order at www.bugzooka.com.


Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.

It’s good to eat and pretty enough for the flower garden

Asparagus is a vegetable that’s good looking enough to be planted in the flower garden. The foliage makes an excellent garden backdrop or can be used in sunny beds to give light shade to flowers that prefer partial shade.  I remember a flower garden where asparagus provided shade for an under-story planting of impatients and verbena. The effect was most attractive as the asparagus foliage created the impression of looking through a light fog.
    The lacy foliage varies from light-green to purplish-green depending on variety. Several harvests of the spears can be made before you allow the stems to grow to maturity.  
    To keep volunteers from taking over your flower garden, seek to buy male plants. If that’s not doable, dig out the berry-producing female plants.
    Asparagus requires advance preparations and well-drained soil.
    Asparagus are grown from roots purchased from nurseries, garden catalogs or garden centers. The roots are generally packaged in bundles of 10 to 25. Most asparagus roots are dug up in the fall and placed in cold storage for spring planting. However, soil preparation should start in the fall with a soil test. Asparagus is a long-term crop, so the pH and nutrient concentrations should be at their optimum levels from the very beginning.
    In commercial production, roots are planted deep to facilitate harvesting and minimize irrigation. Mechanical harvesters cut spears below the surface of the soil.
    Home gardeners who plant their asparagus roots deep can cut the spears underground, harvesting white-stemmed spears. Asparagus crowns can alternately be planted just a few inches below the surface of the soil. But shallow-planted beds are likely to need irrigating.
     To prepare an asparagus bed for cutting spears below the surface of the ground, remove the top six inches of soil in a trench approximately 12 inches wide. In the bottom of the trench, add a two-inch-thick layer of compost and spade or rototill as deeply as possible. Cover the excavated soil with an inch of compost and blend it with the soil. In the spring, remove about a two-inch layer of soil from the ditch and spread the roots of each asparagus crown, spacing crowns a foot apart. Cover the crowns with two to three inches of the amended soil. Check the trench weekly and add additional soil as the stems elongate. Avoid covering the spears.
    If you are planting the crowns shallow, incorporate a one- to two-inch layer of compost as deep as possible into the soil and dig a three- to four-inch-deep trench for planting the crowns.
    Do not harvest asparagus spears until the beginning of the third growing season. The first harvest should be limited to two or three cuttings. At the end of the harvesting season, mulch the bed with a two-inch layer of compost. For additional growth, spread one-half cup of calcium nitrate per 10 square feet.
    The onion hoe is the ideal tool for weeding asparagus beds.
    I apply Preen only after the harvest is complete with a second application in September to control winter weeds. Preen, which is made from fluoride, is cleared for use on vegetables and will control grasses but only a few broadleaf weeds. It is most effective when applied on clean, cultivated soil and watered or cultivated into the soil immediately. Preen provides weed control for only six to eight weeks.


Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.

Hoe, mulch or a touch of herbicide

The better you control weeds in the garden this year, the fewer weeds you will have next year. Weeds have the capacity of generating thousands of seeds, which means that many seeds scattered on the ground this year will be germinating next year. Not all of the seeds will germinate at once. Many hard seeds can remain in the ground for years, especially if they get buried.  
    Frequent light cultivation while the weed seedlings are small is the best method of control — providing you have the time.
    When cultivating or hoeing, disturb as little soil as possible. The more soil you disturb, the more weed seeds you are likely to stimulate into germination. Most of the weeds in hiding are summer annuals that require being exposed to sunlight to germinate. With ample moisture in the soil, many need only a second or so of light to initiate germination. Many large commercial farms now sow and cultivate their crops at night to minimize weed problems.
    I use a hand-push, single-wheel cultivator with a sharp, flat Nebraska blade that slices the weeds at the soil line. This tool causes little disturbance of the soil, and it can be used with minimum effort. The Weed Bandit is also a good tool for controlling weeds.
    Whatever your tool, it must be sharp. For good weed control when seedlings are young, all that is necessary is to cut the top from its roots.  The roots are not capable of regenerating at this stage of development. You can do all you need by simply scratching the surface of the soil. Controlling weeds that are several inches tall requires more effort and more digging.
    Mulch can also control weeds.  Unless you are using black plastic, mulch tends to make the soil cool. If you are growing tomatoes, peppers or eggplants, delay mulching until the first cluster of fruit is forming. Plastic mulches must be anchored along the edges, lest they blow away. You can mulch with newspaper, but you’ll need 10 to 12 layers to provide adequate weed control. Unless kept wet or anchored, the paper can blow away. Shredded paper or cardboard makes better mulch because both are easily spread and, once wetted down, tend to mesh together and stay put. The other nice thing about using paper is that it will rot in place and leave little residue because it is pure cellulose.
    Straw is often used in the garden, especially around tomato and pepper plants.  However, unless the straw is free of weeds, it can be a source of more and different kinds of weeds next year. Never use hay as it is generally loaded with seeds.
    The only herbicide I feel comfortable using to control weeds is Preen. A fluoride, it is effective only on germinating weed seeds. It has no effect on weeds once they have germinated. It must be applied on clean cultivated soil and watered immediately. I use it in my asparagus bed only after we have finished cutting. I use it in the onion bed two to three weeks after the transplants have been planted. I also use it with carrots, parsnips, radishes and beets after the rows have been thinned to the proper spacing. It is useful in the flower garden applied one to two weeks after transplanting.
    To avoid injury, Preen must be applied as directed. It will provide control of crabgrass, goose grass and a few other weeds for six to seven weeks. This is time enough for the crop to shade the ground and the weeds.


Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.

You don’t have to wait until 2061 to delight in its offspringHill in compost to enjoy potatoes early and late

There is nothing like going into the garden and digging a nice big potato with a thin skin for dinner. A freshly harvested white potato from a plant still actively growing guarantees you not only great satisfaction but also a vegetable that is filled with vitamins because you don’t have to remove the skin to eat it.
    If you plan ahead, you need not wait for the potato plant to die back to the ground before you start harvesting.
    It’s common to grow potatoes by hilling them with soil, which stimulates the plants to generate rhizomes on which the potato grows. Part of that way of planting is to wait to harvest the potatoes until after the plants have died back to the ground. Late-harvested potatoes store better. But you have to wait to eat freshly dug potatoes. That’s a delicacy I enjoy as early as possible in the summer, so I hill my potatoes using compost made from leaves raked the previous fall. The compost still contains a large percentage of partially decayed leaves, but it is rich brown, light and easy to handle. I apply six inches of the compost as soon as the plants have grown a foot tall. Lift the bottom leaves of each plant so they don’t come in contact with the ground but are supported by the compost.
    As soon as the plants have grown another 10 to 12 inches, I apply another six to eight inches of compost, again lifting the bottom leaves from the ground and firmly applying compost along the stems. Another application of compost is made after the plants have grown another foot, which generally occurs when the plants are beginning to flower. By the third application of compost, the mounds surrounding the plants are about 18 inches high. After the third round, I hoe a thin layer of soil over the hills of compost to help keep it in place. Covering the compost with soil also helps to keep it moist so that it will continue to decompose while in the garden.
    Since the compost remains loose, it is easy to sneak your hands down around the roots of the plants and harvest a potato or two without disturbing the plant. Harvest no more than two potatoes from each plant this way.
    After the tops of the plants have died back to the ground, the potatoes are easy to dig because most will have grown in the mound of compost, though some of the larger potatoes will have grown in the soil beneath the mound of compost.
    The area where the potatoes had been growing can now be raked smooth and lightly roto-tilled in preparation for planting the fall crop of cabbage, broccoli, cauliflower or rutabaga.
    Over the years, I have found fewer potato beetle problems when using this method. Other compost-hill growers have reported similar results.


Ask Dr. Gouin your questions at DR.FRGouin@gmail.com. Please include your name and address.