view counter

Features (Gardening)

Use this summer to grow big bulbs for fall harvest

I like to plant onions in early April. But if you have not ordered your onion plants yet, there is still time.
    Forget about those onion sets that only produce green onions, or scallions. Grow some real bulbing onions like Copra, Candy, Big Day, Super Star and Sweet Spanish. If you want to grow onions this summer, make certain that you order long-day or intermediate onions. Do not order short-day onions because they will produce only green onions during summer’s long days.
    Onion plants are sold in bunches of about 77 plants.
    Onions grow best in soil rich in organic matter with a pH between 6.2 and 6.8. If you have not had your soil tested in the past three years, now is the time to have it done.
    Prepare the planting beds by first spreading an inch-thick layer of compost over the area and tilling it in. Avoid stepping on the prepared soil; it needs to be nice and loose so the small onion plants can be pressed in easily.  
    To maximize production, I plant in beds about 2 feet wide the length of the garden. The average spacing for most onions is four by four inches. To facilitate planting, I have built myself a dibble board. The board is two feet long and four inches wide. Into it I drilled pegs cut from a broom handle and glued to quarter-inch dowels.
    Press the dibble board into the loose soil and insert an onion plant into each hole. The planting holes are evenly spaced so the onions can easily be cultivated with an onion hoe’s narrow blade.  
    After planting, place a shower head at the end of the hose and water the  bed thoroughly so that loose soil is washed into each planting hole.  
    To minimize weeding, I apply Preen three to four weeks after planting. Irrigate the Preen into the soil immediately after applying it.  Top-dress the onion beds in early June.
    As soon as the onion tops start turning brown, in mid to late August, knock the tails to the ground with the back of a rake. You’ll minimize neck rot without having to apply fungicide.
    Eat at once or, for storage, leave in the ground until the tails wilt and dry. Then harvest, braid and hang out of sunlight in open air.


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

This New England transplant finds our warm summers and mild winters great for growing a wide variety of plants

From where I come from, I wonder if you properly appreciate all of your Maryland gardening advantages. I lived and gardened in central New Hampshire, where summer includes the last two weeks in July and the first two weeks in August, and where winter temperatures can drop to 30. So I know that gardening in middle and southern Maryland is heavenly.
    The long colorful springs months, warm summers, long falls and relatively mild winters all are conducive to growing a wide variety of plant species. Our winters are cold enough to allow us to grow a large number of northern species yet mild enough to grow many southern species. Plus, we get a long vegetable gardening season.

    New Hampshire, the granite state, is true to name. The soil is mostly acid and stony. Piles of stones are common near many home gardens. The large stones were used to build stone walls, while the small stones filled the voids between the large ones.
    We were grateful for paper-white birch, balsam fir, red, white and black spruce and especially sugar maples. My brother and I made maple syrup from the sap of sugar maple trees growing in nearby woods and along country roads.
    For shrubs, we had witchhazel, hills of snow and PeeGee hydrangea — plus mountain laurel in very sheltered areas. Only the branches of forsythia that were covered by snow for most of the winter could flower. But every home had a lilac.
    Of beautiful crape myrtle, colorful hydrangea, camellias, pyracantha, photinia, nandina or Japanese, Chinese and English hollies, we were deprived. We never had dogwoods or purple-flowering redbuds growing wild in the woodlands. I managed to grow a star magnolia in a very sheltered area but it seldom flowered.
    On the other hand, the cold climate was conducive to growing many cultivars of apples and pears, high- and low-bush blueberries, cranberries and many different cultivars of raspberries. Every home had a rhubarb patch. But it was impossible to grow figs or peaches.
    We did not dare to plant the vegetable garden until late May except for peas and potatoes. Asparagus were not ready to harvest until early June.
    We could grow cold-loving crops — broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, celeriac, kohlrabi, parsnips, rutabaga and turnips — all summer long. But I could never grow okra, peppers or large watermelons.
    Tomatoes could not be transplanted into the garden until early June, and by early September they had to be harvested for either ripening behind the kitchen stove or for making pickle-lily. All my fall crops had to be harvested by late September.
    March and April were known as the mud months because the snow melted dirty brown and left mud puddles along roads and sidewalks.

    Turn to Maryland and spring is a continuous blast of color starting with serviceberry, dogwood, redbud, spice bush and mountain laurel. In home landscapes, camellia, flowering quince, cornelian cherry, forsythia, flowering dogwood, Korean dogwood, rhododendrons, azaleas, Andromeda, mountain laurel, cherry laurel, leucothoe and skimia all flower in succession.
    In Deale, which I consider Southern Maryland, I  enjoy gardening from early March until just before Christmas. The first crop to be harvested in the spring is sweet and delicious parsnips.
    As soon as the soil can be tilled, in late March, while soil temperatures are below 60 degrees, I start planting potatoes, bulbing onions and peas. By mid-April, the asparagus is producing shoots that are harvested two to three times each week.
    Seeds of carrots, beets, radishes and parsnips can be sown in cool soils as well. So can broccoli, cabbage, cauliflower, celery, kohlrabi, lettuce and spinach plants that have been properly conditioned in early April.
    As soon as soil temperatures rise above 60 degrees in early to mid-May, seeds of sweet corn and snap beans can be sown. Thus, we can eat freshly harvested sweet corn on the Fourth of July.
    By late May to early June, seeds of melons, squash and cucumbers will sprout within days of being planted. Soon after night temperatures stop dropping below 50 degrees, tomato and pepper plants can be transplanted and seeds of okra can be sown. 
    In late July or early August, the cold-loving crops of the cabbage family can be planted for harvesting from mid-October until Christmas. Nothing like eating freshly picked Brussels sprouts at Thanksgiving dinner and at the Christmas banquet.
    Peas also do best planted in early August, giving me seven or eight harvests before a hard freeze kills the plants. However, spring-planted peas in Maryland can be harvested only twice before the weather becomes too warm for the plants to continue flowering.
    Short-day onions can even be grown in a cold frame or tunnel during winter.
    I still miss the fun of ice fishing, snowshoeing and skating in New Hampshire. But the joy of being able to grow a wide variety of flowering plant species and harvest from my garden eight months each year makes it all worthwhile.


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

Make a bed or make way for stalks now pushing up

Time to turn your attention to asparagus. One of spring’s earliest crops, asparagus is typically ready for cutting in Maryland between April 25 and June 15.
    If your bed is already planted, it needs prepping. Winter weeds have most likely covered the beds, and the old asparagus stems are still sticking above ground. While the soil is still cool, asparagus roots are not yet energized. As soon as the soil dries sufficiently so it will not clump on the hoe or tiller, adjust the cultivator or tiller so that the blades will not penetrate the soil more that two inches. Cultivate or till weeds and those old asparagus stems into the soil. Allow the soil to dry for at least a week, then repeat. Cultivating the soil will hasten its warming, which will hasten the sprouting of asparagus stems.
    If you wish to delay the emergence of asparagus spears, cover the cultivated beds with four to six inches of straw. The straw mulch will shade the soil, retarding warming.
    Under normal conditions, asparagus beds should not be fertilized or mulched with compost until after harvesting. But they should be kept weed-free. Hand weed with a hoe immediately after making a harvest of spears.
    If you’re starting a new asparagus bed, now is the time. Choose a full-sun spot with well-drained soil. Dig a trench 10 to 12 inches wide and eight to 10 inches deep. Place one to two inches of compost in the bottom of the trench, and spade the compost into the soil to a depth of four inches.
    Place the asparagus crowns over the spaded soil at eight-inch intervals, spreading the roots uniformly flat. Cover with about two inches of soil amended 1-to-1 with compost. As the asparagus spears begin to grow, continue adding amended soil to the trench until it is full.
    Do not harvest any asparagus spears for at least two years. Allow the foliage to grow to its maximum height, cutting the stems to the ground in late fall when they have completely turned golden-brown. By delaying cutting, you allow residual nutrients in the stems and leaves to return to the roots.
    After you have cut the asparagus back to the ground in the fall, mulch the bed with a two-inch-thick layer of compost. This not only helps to insulate the bed, it also supplies all the nutrients for next year.
    In the third year, you may start harvesting asparagus spears in the spring. During the first year of harvesting, you should limit your harvests to two. For maximum recovery, cut the asparagus spears just below the surface of the soil using a sharp knife.
    If you prefer eating French-style asparagus, white spears, build a low frame, 10 inches to a foot high above a section of your asparagus bed and cover it with black plastic. The same wire hoops used for building small tunnels can be used to support the black plastic. To prevent heat build-up, leave both ends of the tunnel partially open. Asparagus that develops in total darkness will be white and tends to be tenderer than green asparagus.


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

Clip right to force branches of flowers

Now is the time to force forsythia, quince, magnolia, crabapple, lilac and weigela branches into flower. Select heavily budded branches from the center of the plants so as not to distract from the natural appearance of the plant when it flowers later in the spring. Flower buds are easily distinguished this time of year because they tend to be plump as compared to vegetative buds. In many species, the ends of the flowering buds are rounded.
    If the container for your arrangement is large like a crock, you will achieve a better effect if you first make a large loose ball with chicken wire. The holes in the chicken wire enable you to stand the branches upright or at any angle. Fill the container two-thirds full with 100-degree water.  
    Cut the branches longer than needed so that when you bring them indoors you can make a second cut just before arranging them in the container. Using sharp pruners, cut the stems at a slight angle and quickly immerse them in the warm water. Freshly cut woody stems will absorb more water when placed in warm water than if placed in cold. Cutting the stem at a slight angle also makes larger openings in the stem’s sieve cells, which absorb the water.
    Don’t bother misting the branches and buds. Misting actually delays flowering because as the water evaporates, it causes cooling.
    To maintain a succession of flowering branches, wait 10 to 12 days before harvesting more branches for forcing. Put them in warm water in an out-of-the-way place, adding these just-flowering branches to your arrangement when the first batch starts dropping petals. As outdoor temperatures become warmer, it will take less and less time to force branches into flower.
    Try mixing forsythia branches with saucer or star magnolia branches. The magnolia will be slower in forcing but will add additional color to your arrangement.


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

Hard-working pods make fat peas

March 17 is the day many gardeners plant peas. So it’s time to know a little about them.
    Did you know that the green pea pod generates most of the energy needed to swell the peas in the pod? It would seem that the leaves on the vine would be contributing. However, research shows that only the leaves immediately adjacent to the pod contribute to the formation of the flowers and the pod itself. Once the pea pod has formed, it generates the energy that causes the peas within to expand. 
    This discovery was made after a researcher wrapped up a newly formed pea pod. At that stage of growth, the pod was flat. Covered with opaque tape, the pods did not produce peas. Covering one-half of the pod produced small peas. Different colored opaque materials gave similar results.
    To study the energy source that produced the pod, he removed one, two or three leaves above and below the flower on the vine. Removing leaves adjacent to the flower reduced the size of the pod. Removing leaves from the vine above the flower had no effect. Removing two of the leaves below the flower had the greatest effect on reducing the size of the pod. Removing the third leaf below the flower had little effect. Thus, the leaves closest to and below the flower had the greatest effect on the growth of the pea pod.
    This is more than an idle-hands study. It proves the importance of proper spacing of seeds and of growing peas where they will receive maximum sunlight. If you use too many seeds, the plants will be crowded, causing more vine and fewer pods and peas because both the pods and the adjacent leaves will most likely be shaded.
    Peaches, plums and apples have similar leaf and fruit association. Only the leaves adjacent to the fruit generate the energy to cause the fruit to grow and sweeten. All of the other leaves on the tree provide energy for the tree to grow new leaves and branches. This is another good reason for pruning because pruning allows the sun to penetrate to the regions of the tree where fruit is growing.
    The knowledge gained from such studies has resulted in the development of new pruning and training practices. If you visit a newly planted orchard, you will see apple, plum and peach trees being trained on trellises to minimize the growth of the tree and to maximize fruit production. 
    This knowledge has helped us understand partitioning. Partitioning means that plants have evolved systems for diverting energy for specific purposes. Most of the leaves on pea vines and fruit trees are designated to grow the plant. Only those leaves nearest the flower and fruit produce the energy to grow the fruit. In the case of the pea, the photosynthesis of the pod produces the energy to grow the peas within.


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

What you don’t know can kill a tree

Did you know that only roots less than one inch around are capable of generating new roots from the cut end? Did you know that the cut end of a small root can only grow three new roots at the most?
    Roots are not like branches. When you prune away the end of a branch, you stimulate the development of side branches. Root regeneration only occurs at the ends of the cut root.
    Root pruning is common in commercial nurseries where large trees are grown in the ground. Root pruning starts when the seedlings or rooted cuttings are first planted in the field, always after woody plants have stopped producing new leaves in the first flush of growth. It works to stimulate multiple branching of roots as close to the stem as possible so when the plant is dug and transplanted into your landscape, it will have a better chance of survival. Roots are typically pruned every two years with greater distance from the trunk each time.
    It’s done by making a circle of deep cuts at the plant’s drip line, severing the roots with a sharp spade.
    Root pruning during shoot elongation and leaf growth often results in severe wilting and loss of foliage, thus weakening the plant.
    However, there comes a time when the plants become too tall or wide and root pruning is no longer feasible. If root pruning were delayed until pruned roots are larger than one inch in diameter, many trees would die because large diameter roots are unable to generate new roots.
    So you take a risk when you decide to dig up a well-established plant to move it or cultivate a plant from a wooded area for transplanting into your landscape. Pruning away branches to achieve a balance between the top and the loss of roots only makes matters worse.
    Large roots can be stimulated to generate new roots by inserting toothpicks into the sides of larger cut roots. Soak wooden toothpicks in a concentrated solution of rooting hormone. Wearing latex gloves, use an icepick to pierce a hole in the side of the root and insert a treated toothpick into the hole. The rooting hormone in the treated toothpick will stimulate new roots to grow from the side of the large roots.

Native seeds need to cool down before sprouting

Seeds of native plants in the temperate region require chilling, called stratification, before they can germinate and grow seedlings. The acorn of the mighty oak must be stratified before it can germinate in the spring. But don’t go placing acorns in the freezer before planting.
    In nature’s cycle, acorns fall to the ground in the fall, while the ground is still warm and moist. On the ground, some are covered with leaves; some are gathered and buried by squirrels. Soon after landing, acorns begin to absorb moisture. Slowly, the ground cools. As soon as soil temperatures drop to near 45 degrees, stratification begins. When soil temperatures drop below freezing, stratification stops. As temperatures rise above freezing, stratification continues. Nature’s alternate freezing and thawing enhances germination.
    Each plant species has its own length of time for stratification. In species that grow over a wide range of latitudes, stratification periods can vary considerably. For instance, the red maple tree has a growing range from ­Quebec to northern Florida.
    The stratification period for seeds taken from trees native to Quebec is shorter than for seeds from trees native to northern Florida. This is because the ground freezes earlier and stays frozen longer in Quebec than in northern Florida. In northern Florida the soil seldom freezes hard, but it is cold enough that seeds germinating in early spring would be killed by frost. This phenomenon was verified when red maple seeds harvested from trees growing near Quebec were planted in northern Florida and seeds harvested from red maples originating in northern Florida were sown in soil near Quebec. The Quebec seedlings germinated in the middle of Florida’s winter and were killed by frost, while the seeds from Florida never germinated in Quebec.
    To artificially stratify seeds from our region, mix them with moist sand blended with some peat moss and allow them to absorb moisture for at least two weeks. Then refrigerate for another six to eight weeks before sowing. This is more or less following the normal daily temperature cycle.
    The lazy way of germinating native plant seeds is to sow them in the fall in a well-prepared soil with at least three percent organic matter. Cover the seedbed with a board to prevent winter weeds from growing. The seeds will undergo natural stratification.
    In the spring, at about the time the buds of trees are starting to show color, remove the board covering the seed bed and watch for seedlings to emerge.


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

Some bloom only in short days; ­others, only in long days

Did you know that in many plants, flowering — and bulbing — is based on the number of hours of exposure to light?
    This fact of plant biology explains many mysteries. Understand it, and you’ll be a smarter and more successful gardener.
    If you expose a chrysanthemum or poinsettia to more than 11 hours of light each day, it will never flower. The triggering mechanism that forces these species into flowering is exposure to no more than 10 hours of light. Those conditions of light are called short days and long nights. Interrupting their 14-hour night with even a flash of light can prevent flowering.
    During long daylight hours, greenhouse growers cover these species with shade cloths to force them to flower out of season. That’s why chrysanthemums are available throughout the year.
    Nature’s cycle of short days and long nights begins in late summer. This natural cycle enables us to enjoy fall mums and greenhouse growers to grow poinsettias without having to shade them.
    In the fall, some chrysanthemums flower earlier than others. This range is possible because breeders have developed cultivars with different maturing periods. Chrysanthemums’ short-day classification further divides into six-week, eight-week, 10-week and 12-week cultivars. These numbers refer to the number of weeks from the time a plant is exposed to 10 or fewer hours of light until the flower buds show color. By selecting different varieties, you can have chrysanthemums flowering in your garden for many weeks.
    Short-day woody plants include azaleas, rhododendrons, dogwoods, lilacs, spring-flowering roses and viburnums, to name a few. The flower buds on these plants are produced late summer and early fall for flowering in the spring.
    Long-day plants flower all summer long.  This includes bedding plants and woody ornamentals such as fuchsia, crape myrtle, hybrid-T and floribunda roses, some hydrangea and hibiscus, among others. When daylight hours fall under 10, the plants remain in a vegetative state of growth.
    Many varieties of onions are also classified as long- or short-day varieties. For long-day onions to form bulbs, they must be planted in the spring and form bulbs when the days are long. Short-day onions — as well as garlic — are planted in the fall and form bulbs when daylight hours are short. Plant short-day onions in the spring, and you’ll only get green onions.


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

Turn that manure into compost instead of applying it to fields

The new governor of Maryland has made a major error in allowing poultry farmers to continue applying their phosphorus-laden chicken manure on land that is already overloaded with phosphorus.
    What the chicken farmers and the governor are ignoring is scientific evidence that clearly identifies excessive levels of phosphorus in soils as the cause for phosphorus-induced trace element deficiencies, lower yields, lower nutrient values and Bay pollution.
    The smarter strategy is to grow soybeans one year then corn the next. Legumes like soybeans fix their own nitrogen and leave plenty in the ground to grow a crop of corn the following year. If this rotation were followed, farmers would only need to apply potassium when soil call for it. When the soil needs potassium, it can be added as either potassium chloride or potassium sulfate, both cheaper to apply than tons of chicken manure.
    Phosphorus is essential to plant growth. But too much causes other essential plant nutrients to bind to it, starving plant roots. Such essential trace elements as iron, zinc and copper are essential to plant growth, as are nitrogen, phosphorus, potassium, calcium and magnesium.
    In the mid 1970s I was asked by fellow University of Maryland faculty members who specialized in vegetable crops to review soil tests from fields of sweet potatoes near Salisbury. The total phosphorus levels in those soils were so high that they were reducing yields. I recommended they stop applying phosphorus and apply only nitrogen. This was a major change in culture for these farmers because they had been accustomed to applying tons of 10-10-10 before planting each season’s crop.
    So much phosphorus had been applied that it took several years with none before yields started to increase.
    In the early 1980s, rhododendron growers tried dosing their plants with lots of phosphorus to force them into flower under shade. It worked, but it also stunted growth and caused iron deficiency symptoms on the foliage. Full sun alone would have produced healthy tall plants with flowers.
    My conclusion from these and other studies is that plants do not need much phosphorus to be productive.
    Over-applying phosphorus not only leads to reduced yields and lower nutritional value. It also contributes to Bay pollution.
    Allowing farmers to make yearly applications of chicken manure on soils already saturated with phosphorus lowers yields of grain and forage crops. Since most of these farmers do not plant cover crops, their phosphorus-enriched soils erode into the Bay.
    There are other better uses for chicken manure, as compost or as a source of energy. The ornamental horticulture industry — the second largest agricultural industry in Maryland and the nation — is a ready market for quality compost. Yet Maryland has to import compost from as far as Maine to meet its needs. Maryland Environmental Services is well versed in the science and technology of making compost.
    Gov. Hogan, please encourage chicken farmers to form a co-op to manufacture and market compost.


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

Getting to the roots of woody plants

Did you know that when the stems of an oak tree are growing in the spring, the roots are not growing? Conversely, when the top of the plant has stopped growing and has stopped producing new leaves, the roots initiate growth. It’s the same with most woody plants. Most are unable to grow at both ends at the same time.
    In the spring, the stems and leaves are elongating and unfolding, while the roots are busy providing them water and nutrients. At maturity, the full-sized leaves begin sending down compounds such as carbohydrates, hormones and other metabolites used by the roots to produce new roots. In some plants, this cycle repeats itself. Many deciduous species will produce two or more flushes of top growth with brief periods of root growth. In other plants such as pine trees, there is usually only one flush of growth.
    Plants need to grow new roots because nutrients are absorbed only at the tips of roots. Nearly all nutrients are absorbed by root hairs, and these only occur on newly formed roots. As soon as new roots begin to form, the root hairs deteriorate, and that part of the root is covered with suberin, a sugar-like substance that enables the root to absorb only water.
    In other words, most of the roots of plants function as pipes, carrying nutrients and water to the stem when the tops are growing, then carrying metabolites to their own tips when roots are growing.
    This is knowledge you need to transplant trees and shrubs successfully. To assure better survival, growers root-prune plants a year or two before transplanting. To root-prune, make a circle of deep cuts at the plant’s drip line, severing the roots with a sharp spade.
    Wait until after woody plants have stopped producing new leaves in the first flush of growth. Root pruning during shoot elongation and leaf growth often results in severe wilting and loss of foliage, thus weakening the plant. Late-summer root-pruning has another advantage. More buds have formed, resulting in the maximum production of natural hormones that stimulate new roots.
    Annual plants are another story. In annuals, tops and roots grow simultaneously. This is possible because these plants have the advantage of growing only during long days and warm weather.
    Understanding root growth also helps you care for potted plants. Plants grown in containers have limited space for root growth. Keeping the plants in the same container for too long results in root-bound plants. There is no more room for roots to grow. Root-bound plants deteriorate or may flower profusely, wilt frequently and stop growing. Those are signs that it’s time to repot. When repotting, slash or tear apart the root ball to stimulate new roots to grow.