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Features (Gardening)

Organic matter adds ­hidden benefits to soil

Addition of organic matter does great things for soil. It works as a slow-release fertilizer and source of essential nutrients. It reduces the density of heavy silt and clay loam soils. It improves soil’s nutrient retention and increases water retention. All of these benefits redound to plant growth.

Retention of nutrients
    Adding organic matter to soils increases the retention of nutrients and makes them available to the roots of plants. This process is known as increasing the cation-exchange capacity of soils. You learned in the July 24 column how organic matter releases nutrients slowly through mineralization. In addition to supplying the major elements, compost supplies trace elements such as boron (B), iron (Fe), zinc (Zn), manganese (Mn), sulfur (S) and copper (Cu). These essential trace elements are important to the growth of healthy plants and to the quality of the crops they produce. But they’re not part of commercial fertilizer mixes.
    Increasing the cation exchange is especially important in sandy loams or loamy sands. Nutrients leach through these sandy soils quickly. Because sandy soils are well aerated, they do not retain organic matter. So to maintain productivity on sandy soils requires frequent applications compost or animal manure and the use of cover crops.
    On sandy loams or loamy sands, use no more compost or manure than six cubic yards per 1,000 square feet for the initial application. On silt or clay loam soils, make that four cubic yards as these soils are better able to retain nutrients than sandy loams or loamy sands. Repeated applications should be one-half or one-quarter.
Water-holding Capacity
    The addition of organic matter to sandy soils increases water-holding capacity.
    The addition of organic matter to heavy silt or clay loam soils increases water infiltration, thus increasing their ability to retain water while at the same time allowing excess water to drain.

Soil Density Reduction
    It won’t work to use sand to improve the drainage of heavy silt or clay loam soils. Short of 55 to 60 percent, the addition of sand will only result in making the soil like concrete.
    Adding 10 percent compost will increase both the organic matter concentration and the productivity of heavy silt or clay loam. Pine fines are one of the better organic materials to use to lighten heavy soils. Pine fines are a waste product from the manufacturing of pine bark mulches. Because pine fines contain high levels of lignins — a source of organic matter that resists decomposition — pine fines will persist in the soil for a long time.

Disease Control
    Another hidden benefit of amending soils with compost is its ability to control soil-borne diseases. Quality compost contains three naturally occurring fungicides and numerous beneficial microorganisms known to control common soil-borne diseases as fusarium, pythium and rhizoctinia. To get this bonus, use recently made compost. As the compost ages, these benefits are gradually lost as the biological activity of the compost decreases.

Lesson 3: Jumpstart your garden with compost tea

     Your organic garden will need a jumpstart. Organic gardening relies entirely on the release of nutrients from the decomposition of organic matter and the bodies of the microorganisms that digest the organic matter in the soil. In cold soils, nutrients are not readily available.
    Room temperature — a consistent 72 degrees — is the starting point for analyzing the situation. With 72-degree soil temperature, the rate of the mineralization of organic matter is approximately eight to 10 percent. If the soil contains three percent organic matter, it releases 24 to 30 pounds of nitrogen per acre per year. Producing a respectable crop takes between 80 and 100 pounds of nitrogen per acre.
    In summer, when soils are at room temperature and above, it takes a soil with five to 10 percent organic matter to produce a respectable crop. Even if soil temperatures increase above 72 degrees, the mineralization rate increases only a few percentage points. To grow a crop in soils containing less than five percent organic matter, you’ve got to add organic fertilizers, including compost. As the microorganisms that digest the carbon of the organic matter die, the minerals in their bodies and in the cells of the organic matter are released.
    The cooler the soil, the slower the process. Mineralization of nutrients from organic matter stops when the ground freezes. In spring, the mineralization rate of organic matter is not nearly up to summer’s eight percent. Even if the soil contained five to 10 percent organic matter, it would not supply sufficient nutrients to grow early spring crops such as cabbage, broccoli, cauliflower, celery and lettuce.
    Traditional agriculture uses starter fertilizers with early spring transplants. Starter fertilizers are made of water-soluble minerals that are instantly available to the roots of plants, regardless of soil temperature. Applying these fertilizers near the roots of new transplants helps establish them quickly in the soil and resume normal growth. 
    Compost tea can be used as starter fertilizer. Brew the compost tea at room temperature three or four days prior to transplanting. Partially fill a five-gallon pail up to half capacity with mature compost. To assure maturity, I strongly recommend using commercial compost. Top with water and stir vigorously. Stir the compost three or four times daily to provide adequate aeration for nutrient release from the compost. Or you can aerate the compost using an aquarium air filer as a substitute.
    When you transplant three or four days later, irrigate each plant with one to two cups of compost tea.
    A second batch of tea can be made using the same compost by filling the pail again with water and repeating the process. The second batch will not be as concentrated as the first unless you allow a week or more for it to release its nutrients into the water.

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.

Otherwise, you’re planting trouble

Every year, readers complain to me that some of their plants are flowering either poorly or not at all. That junipers, Japanese hollies and other shrubs have dead branches or worse. That their plants are so leggy. That tree roots have cracked their sidewalks. Last year, a reader asked what would cause the cement block in his basement to crack and bulge.
    As plants grow, they require more room. Some plants grow more vigorously than others. Many people plant without planning or knowing anything about the plants they have purchased. All kinds of trouble results.
    Crowding is one the consequences. Few gardeners can afford to purchase mature plants when landscaping their home or planting their flowerbeds. Most of the trees and shrubs sold in garden centers are one-tenth to one-quarter their mature size. This is also true for bedding plants and vegetable transplants. Because the plants are small, there’s a tendency to plant them close together to fill the space as rapidly as possible. The problem is that plants quickly grow together and compete for light. Some of the more vigorous species, especially when planted on the south, begin to shade the slower-growing plants. The better prepared the soil, the quicker the growth.
    Crowded plants are forced to grow tall and spindly with weak stems. The thickness and strength of a plant stem is directly related to the frequency of bending and the number of branches or leaves originating from the stem. Plants that are crowded do not sway with the wind as those that are more exposed. Crowding also prevents side branches and leaves from developing on the stem. As a result, the stem does not increase in diameter and remains weak. Crowding also inhibits flowering.
    Many flowering plants such as azaleas, rhododendrons, roses, crape myrtle, lilacs and Korean dogwoods produce the maximum flowers when planted in full sun. The plants may have been planted in full sun initially, but surrounded with a more vigorous or a taller-growing species, they extend their shade over the slower-growing flowering species. As the flowering plants are exposed to more shade and less sun, their ability to produce flowers is reduced.
    Other species of ornamentals will grow only in full sun. Junipers, Japanese hollies, pine, spruce, fir, arborvitae, chamaecyparis and others deteriorate when planted in shade. As these species are exposed to more and more shade, the plant’s branches die back. Many gardeners associate the dieback with disease and do not realize that the branches are dying from insufficient direct sunlight.
    As the roots of trees grow in diameter, the force that is generated can lift concrete walkways. For planting near walkways or foundations, select trees that will produce deep roots and plant them at a sufficient distance to develop without damaging structures. Trees should never be planted closer than 20 feet from a foundation. I have seen cement block foundations crack and bulge from the pressure exerted by expanding tree roots.
    Before purchasing plants, take time to read the information about each species, select those that best meet your needs, recognize their mature size and make certain that the plants you select will receive the amount of sun they need.


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