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Features (Gardening)

Grow a patch of rhubarb

My old friend Bill Burton and I once discussed eating freshly harvested rhubarb as kids during hot summer days in New England, where every home had a rhubarb patch in the backyard. Bill raved about his mother’s rhubarb-custard pie, while I raved about my mother’s strawberry-rhubarb pie. I can still picture myself sitting on the back stairs of our home with a fist full of sugar in my left hand and a freshly harvested stalk of rhubarb in my right. Before each bite, I would dredge the base of the rhubarb stem in the sugar.
    Those were the days.
    Rhubarb is a vegetable, not a fruit, although we tend to limit its use to making desserts. One of the great features of rhubarb is that it can be blended with other fruit such as strawberries, blueberries, apples, pears and apricots as the rhubarb absorbs the taste of the fruit. In other words, you can make a tasty blueberry pie using only one cup of blueberries and two cups of chopped rhubarb.
    Rhubarb grows best in well-drained soil in full sun. It can tolerate partial shade, but it will produce spindly stems. Since you consume only the stem, the fleshier the stem the better. Never eat the leaves because they contain oxalic acid, which will cause swelling of the tongue.
    I have seldom seen rhubarb sold in a garden center, though it is commonly listed in seed catalogs. If you order rhubarb for your garden, you will receive in the mail what appears to be a dried-up brown stub. For best results, place it in a cup of water for five days before planting.
    There are various clones of rhubarb with stems ranging from green to various shades of green to red and red only. There is even a clone labeled Strawberry-rhubarb. I can assure you that it does not have a strawberry flavor.
    Rhubarb likes mildly acid soil with a moderate amount of organic matter. When planting rhubarb, I dig a hole the size of a half-bushel basket and add two to three shovels-full of compost and a handful of agricultural limestone, then mix thoroughly.
    Allow the rhubarb to grow without harvesting for at least two years before pulling your first stems. During your first harvest on the third year of growth, remove no more than half of the stems at any one time and allow one month between harvests.
    If you see a flower head develop in the center of the clump, remove it with a sharp knife two to three inches from the ground. Allowing the plant to produce seeds during the first three years of growth will weaken the clump.
    Never try growing rhubarb in a large container or in a raised bed. The roots are sensitive to high temperatures, which will cause the plant to die in mid-summer as rooting media rises in above-ground containers or beds.

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A successful harvest depends on the right bulbs for our hours of light

Onions are good for your health, and generally they are easy to grow. Let me give you some advice on growing them successfully.
    Plant onion sets and you’ll harvest only green onions. Most sets you buy are short-day onions, which produce bulbs only when grown during the winter months with 10 daylight hours or less. Planted in the spring, as daylight hours grow longer, they produce only onion tails, your green onions.
    To grow onion bulbs, you must buy either long-day or intermediate, aka day-neutral, onions. They are shipped in bundles of 75 or more seedlings. Unless you are familiar with a particular variety, I suggest planting two or more varieties. Harvesting will be easier if you keep each separate in the garden, as they’ll mature at different times.
    Onions perform best in high organic soils with a nearly neutral pH.
    The spacing between onion plants is based on the mature bulb size. The most desirable bulb size for kitchen use is one and a half to two and a half inches. For those sizes, use a four-by-four-inch spacing. Bermuda and Walla Walla-size onions need more space; plant them in six-by-six-inch spacing. Those spacings allow room for the bulbs to grow and for you to cultivate between the plants without damaging the bulbs.
    Fertilize two to three weeks after planting and monthly thereafter. Don’t let the soil dry out; onions have a very limited root system, and there is a high population of plants in a limited area.
    Neck rot of onions can be a serious storage problem. Avoid it by knocking the foliage to the ground just as the bulbs begin to mature in late July and August, depending on the variety. Do so as soon as the color of the foliage begins to fade and the tops of the onion tails start turning brown. I use the back of a garden rake.
    Leeks want four-by-four-inch spacing as they do not produce bulbs but do produce thick stems. They have the same growing requirements as onions.
    Garlic planted last fall is now in need of fertilizer. Like onions, garlic plants have a limited root system and respond well to fertilizer and water. Remove the flower buds as they begin to form, mid- to late June, depending on variety. If the garlic plants flower and produce seeds, both bulb and cloves will be smaller. For large cloves of elephant garlic, early removal of the flower stem is doubly important.

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Many will bloom again in your garden, but some are destined for compost

If you received Easter plants, you’ll be able to plant some of them in the garden to enjoy again next year. Others are best recycled by composting them.
    Replant: Potted tulips, daffodils, hyacinths and crocuses can be planted in the flower garden. Don’t wait until the plants have died back to the ground. As soon as the flower petals have dropped, transplant them by digging a hole 10 to 12 inches deep, place a couple inches of compost in the bottom of the hole and mix with the existing soil. Carefully remove the root-ball from the container, loosen the layer of roots at the bottom of the root ball and place in the hole. The bottom of the root ball should be at least eight inches below the surface of the soil. Blend one-third by volume compost with the soil removed when digging the hole and carefully backfill around the stems. The bottom of the leaves of the plants should be just above the soil line.
    Many forced Easter lilies are not very cold-hardy. Since the frost seldom penetrates more than six inches in Southern Maryland, the bulbs’ lack of cold-hardiness can be solved by planting them 10 to 12 inches deep. Move the plants outdoors as soon as possible and keep them watered. For maximum effect, plant the bulbs in groups spaced 10 inches apart. If you only have one Easter lily, plant it as described above. If you have many (note that your church likely discards its lilies as soon as they have finished blooming), plant them in trenches. Dig a trench six inches wide and 12 inches deep and blend compost into the bottom soil. Carefully remove the plants from their pots and loosen the bottom roots. Space the plants in the trenches and backfill with soil amended with compost. Don’t worry about covering the bottom leaves with soil. What is important is that the bulbs be planted deep enough that the soil protects them from freezing. Your outdoors Easter lilies will flower next year but not in time for Easter.
    Compost: If you received potted hydrangeas, I highly recommend that you add them to the compost pile. The cultivar of hydrangea used in greenhouses does not have cold-hardy flower buds. If planted outdoors, it will produce attractive plants, but unless we have an extremely mild winter, it will not flower. Hydrangeas for outdoor landscaping are different cultivars.

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In spring, feed your soil — not your grass

Warm-season grasses, including Zoysia and Bermuda grass, should be banned from Chesapeake lawns. They cause nothing but problems. Lawns planted with these grasses have to be fed monthly May through August with high-nitrogen fertilizers. They must be sprayed yearly with restricted-use pesticides to control billbugs and other insects. They must be mowed close to the ground, so they often become infested with weeds, which requires the frequent use of herbicides. The clippings must be collected and the lawn dethatched.
    Warm-season grasses are green during the summer months and yellowish-brown in fall and winter. Some homeowners go so far as to spray them with Greenzite in late fall to make them more attractive.
    For the best Chesapeake country lawns, plant bluegrass and fescue.
    Bay soil is better suited for growing cranberries and blueberries than for grass. If you want a lush weed-free lawn next year, late April and early May is when to take action.
    If you haven’t had your soil tested in the past five years, it is likely that you will have to lime your soil. Soil in the Bay area tends to be very acidic. When you apply lawn fertilizers on acid soils, the chances are great that much of the nutrients from the fertilizers will either be washed into the Bay or into the groundwater. If you want your lawn to be dark green and dense, this is the time to apply limestone — not fertilizer.
    Lawn grasses grow best on soils that are only moderately acid. It is not uncommon to find soils in the Bay area having a pH of 4.2 to 4.5. Since a pH of 7 is neutral, this means that such soils are very acid and would be ideal for growing cranberries and blueberries — if we had the proper climatic conditions.
    By applying limestone now, you’ll neutralize your soil, bringing it closer to the ideal pH for growing lawns, between 6.0 and 6.5. In this pH range, all of the nutrients essential for good plant growth are available to the roots of the grasses. In turn, fertilizers you may apply in fall — which is the best time to fertilize bluegrass and fescue lawns — will be effectively utilized by the grasses.
    Soil testing is the only sure way to determine the amount and kind of limestone to apply. If you don’t want to take the time to have your soil tested, then apply between 50 and 80 pounds of dolomitic limestone per 1,000 square feet. Do not use hydrated or high-calcium limestone, since most of our soils are deficient in magnesium, and dolomitic limestone contains magnesium.
    If you live near the Bay, you should not be using weed killers. Matter of fact, weed killers for lawns should be outlawed. Not only are they unnecessary and expensive, they contribute to the pollution of the Bay.
    Working with herbicides almost continuously since 1958, I have respect for them and their responsible use. But the application of weed-and-feed fertilizers is an irresponsible use of both herbicides and fertilizers.
    The time to apply a pre-emergent herbicide to control crabgrass, dandelions and other broadleaf weeds is within two to three weeks following petal drop of forsythia: no later than early May in the Bay area. Applying weed-and-feed fertilizer earlier means that by the time the crabgrass starts to germinate, the pre-emergent herbicide will have become ineffective.
    Applying fertilizer to a bluegrass or fescue lawn late in the spring means that you will be promoting soft, succulent growth that will be susceptible to disease. Then you will have to purchase a fungicide to control the diseases you caused by applying the fertilizer too late in the spring.
    If only a few weeds are growing in your lawn, why apply a weed-and-feed fertilizer over the entire lawn? I have yet to see a decent lawn that needs a weed-and-feed fertilizer treatment.
    If the lawn is nothing but weeds, it is time to start over in August or September. No amount of weed-and-feed fertilizer can reclaim a neglected lawn.

To Test Your Soil
    Send soil samples for testing to Waypoint Analytical (formerly A&L) in Richmond. Full instructions for testing are online:
    If your soil is a sandy loam or loamy sand, have it tested for all trace elements, especially boron (B). However, if your soil is a loam, silt or clay loam, the general soil test will suffice.
    If you have been growing multiple crops each year, you most likely will need to apply limestone. If you want me to make recommendations, don’t specify a crop (a savings of $3 to $5) and include my email so I’ll get your results:

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Great for tight spaces or poor soil

A couple of years ago, I initiated a demonstration on growing vegetables in bales of straw using organic fertilizer and chemical. My test consisted of preparing the bales in two ways. On one, I applied three pounds of 4-3-4 Holy Tone Organic. On another, 2.5 cups of 10-10-10 fertilizer. I kept both bales wet until their internal temperatures were equal to those of ambient air.
    Temperatures in the bales treated with 4-3-4 organic fertilizer reached 120 degrees within days. Temperatures in the bales treated with 10-10-10 fertilizer required at least a week before reaching 110 degrees. All of the bales appeared to show signs of decay, with and inky cap and shaggy mushrooms growing on all.
    After the temperatures within the bales dropped to ambient air temperatures, I seeded the bales with kale, as I conducted my test in autumn. All of the bales produced an abundance of kale; there did not appear to be any differences with regards to yield. However, the kale growing in the bales of straw were not as vigorous as those growing in the nearby garden.
    Soon after minimum temperatures dropped to below 28 degrees. All of the plants growing in straw died. Those growing in the garden continued to produce eddible leaves of kale, which we continued to harvest most of the winter. Come spring of 2015, the kale in the garden resumed growth while the kale grown in the bales of straw was dead.
    Last June, I amended the straw bales treated with Holytone organic 4-3-4 with another pound and a half. I amended each straw bale, initially treated with 10-10-10, with another 1.75 cups. After watering the fertilizers thoroughly, I transplanted one Roma tomato and one Accent Sweet pepper into each bale. The plants were irrigated daily until they appeared to be well established as evident by the rapid growth. From that point on the plants were irrigated twice weekly in the absence of rain.
    The tomato plants quickly outgrew the pepper plants, resulting in only one pepper plant surviving. It did not produce any peppers. The Roma tomato plants produced an abundance of tomatoes in all straw bales regardless of the fertilizer treatment. The editor of Bay Weekly will verify the results because she was invited to harvest the tomatoes for canning.
    By September, all of the bales had shrunk to only a few inches thick with many of the roots of the tomato plants penetrating the landscape fabric placed beneath them at the beginning of the demonstration. The remaining residues of straw went to the compost pile.
    Yes, you can grow tomatoes and peppers as well as kale in bales of straw — providing you plant only one species per bale and not try to grow a variety of plants in such a confined space. The most vigorous species will dominate and crowd out the less vigorous species. Each bale will give you two crops.

Grass and Clover

Q    I have a raised vegetable garden I made last year. Over the winter some grass and clover blew in and is growing pretty good. Would it be better to spade or plow the weeds in the soil, or should I pull them out completely before I plant this summer’s crop?

–Dean Castle, via email

A    Pull out the clover and spade under the grass.

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Hardy ornamental plants will survive, so shape them as you want them

Be ruthless. It’s time to chop ornamental grasses and butterfly bushes. Cut them down to the ground.
    Also remove the old flower stems and old foliage of sedum to make room for new growth.
    In addition, it’s time for serious pruning of lilacs that are over-grown or infested with stems borers. Trim azaleas, rhododendrons, cherry laurels and hollies that make it impossible to look out of the bedroom or living room windows. Some of the branches that you cut can be brought in and forced to flower.
    Late winter and early spring are the best times for hard pruning. The roots of all ornamentals growing in your landscape are packed with sugars, carbohydrates and nutrients just waiting to move upward into the stems to produce new branches and leaves. Hardy ornamental plants survive and flourish no matter how drastically you prune them. So you don’t need to fear killing the plant if you remove too much.
    Cut those clumps of ornamental grasses as close to the ground as possible. To eliminate the need to carry away the old dry stems, cut them into pieces six inches or smaller and allow them to become mulch. While you are at it, cut those stems of butterfly bushes as close to the ground as possible. I use a chainsaw to prune my butterfly close to the ground, forcing new branches to emerge from the roots. If the forsythia and weigela shrubs are over-grown or not flowering well, cut those branches close to the ground as well. This is how you force the new branches to originate from the roots and not from branch stubs.
    Overgrown azaleas, rhododendrons, hollies, yews and cherry laurels should have their branches pruned to 12 to 18 inches lower than the desired height. You will avoid having to prune them again in a few years, and regrowth will have a more desirable appearance.
    You don’t have to be a certified professional horticulturist to know how to prune hardy ornamental plants. These plants are survivors and dormant vegetative buds up and down the branches are waiting to burst into active growth. That plant will recover and appear normal in a relatively short time. Trust me.

Plow Pan Is Your Problem

Q    We have been growing perennials, a few annuals and various vegetables and herbs on the same large garden plot for about 13 years. I’ve noticed that the plants aren’t as healthy as they once were, despite the fact that we’ve added soil and fertilizer over the years. What do you recommend to improve the soil for the garden overall and in particular where the perennials are located?
      –Amanda Gibson, Lothian

A    If you have been gardening in the same area for 13 years, and have been tilling or plowing each year, most likely you have developed a plow pan about six inches below the surface of the soil, and it is now affecting drainage and root penetration. The only solution is double digging or sub-soiling. To test my theory, sharpen a broom handle (or use a piece of half-inch pipe) and see how deep you can push it into the ground. Test several areas in your garden. If you can’t penetrate deeper than six inches you have plow pan and need to dig below. If you have a tractor, I have a sub-soiler you can borrow.

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Asparagus is coming; winter weeds should be going

If you planted a cover crop of winter rye or wheat last fall, most likely the grass is six to 12 inches tall by now. Use your lawnmower to mow the grass as close to the ground as possible. Mowing saves you time in tilling the soil and helps to dry it, making it easier for the tiller.
    Ground left bare will by now be covered with a carpet of chickweed and henbit. Use horticultural vinegar to kill these winter weeds now before they drop their seeds. For maximum control, spray the vinegar on the foliage during a bright sunny day. Within 24 hours, you will see the weeds turn yellow-white with the leaf margins going brown. Friends report good results with a mixture of one gallon of distilled white vinegar with one-quarter cup of Palmolive dish detergent.
    If that bare ground is your asparagus bed, once the weeds have died down, rototill lightly, delaying if the soil is very wet. Before tilling, you can easily remove old stems because most have rotted at the base. Allow the tines of the tiller to penetrate the soil no more than three or four inches so as to not disturb the roots of the asparagus plants, which will soon be sending up shoots
    Readers have asked how to grow white asparagus, which are tenderer than green asparagus and have a milder flavor. White asparagus are grown in the dark. The old method was to hill the beds with soil or sawdust as the spears appeared above ground. The modern method is to build a lightweight frame of wood and cover it with black plastic or roofing paper. As soon as the spears appear, place the covered frames over the beds, lifting every two or three days for harvesting.
    If you have not had your soil tested in the past four years, now is the perfect time to submit a good representative soil sample for testing.
    I recommend sending the soil samples to A&L — now Waypoint Analytical — in Richmond (
    If your soil is a sandy loam or loamy sand, have it tested for all trace elements especially for boron (B). However, if your soil is a loam, silt or clay loam, the general soil test will suffice.
    If you have been growing multiple crops each year, you most likely will need to apply limestone. If you want me to make the recommendations, don’t specify a crop (a savings of $3-$5) and include my email so I’ll get your results: Once I have them I’m happy to consult you.

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It’s not such prickly work after all

A Bay Weekly reader who has tried and failed many times asks how to grow cactus plants from seeds.
    It’s possible. Here’s how.
    For growth, cactus plants need full sun, dry conditions except for a few days of rain in the spring, sandy rather poor alkaline soil that’s hot in the day and cool at night. These are exactly the same conditions you must satisfy to be successful in germinating seeds. 
    To prepare a seed germinating mix, blend one-fourth cup of garden soil with two cups of play sand and one rounded teaspoon of agricultural grade dolomite limestone. Moisten with water and mix thoroughly. Place the mix in a metal or Pyrex pan and bake at 200 degrees for one hour, cooling in the oven. By doing this, you are pasteurizing the soil to kill all weed seeds and living organisms that are not common under desert conditions. Put two tablespoons of the sterilized soil in a clean, sterile container or plastic bag. Place the rest of the sterilized soil in a clean, shallow four- or five-inch pan with drainage holes in the bottom.
    Uniformly scatter cactus seeds over the surface of the mix, allowing one-eighth to one-fourth inch between them. Cover the seeds with the saved pasteurized soil using a tea strainer. Water the seeds carefully with a rose bulb or fine sprinkler until water drips from the bottom of the container. Place the pot near a window facing south where it will obtain full sun all day and cool temperatures at night.
    Commercially, cactus seeds are germinated in lighted cycling chambers with 80 degrees of bottom heat for 12 to 15 hours under grow lights and nine to 12 hours of darkness at temperatures 60 to 65 degrees. You can best achieve the commercial germination chamber with a gooseneck lamp with a 40-watt incandescent light bulb. Adjust the light to 10 to 12 inches above the pot and place both in the middle of a room. Turn the light on soon after you rise in the morning and turn it off before going to bed at night. The heat and infrared rays of the incandescent light bulb will not only provide light but also warm the soil during the day. When the light is off, the soil will cool.
    Most packets of cactus seed contain several species, so germination is very erratic, anywhere from a few weeks to a month or more. Check for soil moisture daily. If the soil feels warm, irrigate lightly. If the soil feels cool, withhold irrigation.

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Put yourself in its place

Oh, the stories I’ve heard of abuse to cactus. I’ve spent many afternoons and evenings in plant clinics where people wheel in large barrel or drum cacti with decaying centers. Often water was oozing from the bottom where it had begun to rot. One elderly lady arrived in a chauffeured limousine. She sent the chauffeur inside to bring me out to examine her plant, a three-foot-tall Saguaro cactus. Before she would allow me to examine her cactus, she requested my credentials.
    My first question to her, and to the other cacti owners I advised, was where the plant was kept at home. Most often, I was told, in the middle of the living room.
    Where do cacti grow? The desert.
    Cacti growing as houseplants need to reside in an area with full sun.
    Cacti are succulents and store large amounts of water in their cells. Because the epidermal layer is thick between the spikes and covered with a chitin like material, they lose little water by evaporation. In the home, most cacti should not be watered more than once a month and should only be fed with a liquid fertilizer once a year.
    They’ll need repotting every four to five years. The soil can be made by blending 10 percent garden soil with 90 percent sandbox or builders sand. To each cubic foot of cacti soil, add one-half cup of agricultural limestone and blend thoroughly. Heat garden soil at 200 degrees for one hour to kill weeds, insects and worms or grubs.
    Because most cacti have sharp spines, they are dangerous. To handle them, crumble many sheets of newspaper into large, tight balls. Put the paper balls over the spines, pressing firmly into place until you can no longer feel the sharp ends.
    To remove a cactus from its pot, slide a long sharp knife along the inner side the container and the root ball. Tip the container on its side and slide out the root ball. If the root ball does not slide easily, strike the bottom of the container with a rubber hammer or with a two-inch-thick board cushioning a carpentry hammer to prevent breakage.
    The new container should be at least three inches larger in diameter than the old and one to two inches deeper. Measure the depth of the original root ball and add soil to raise the top of the root ball to within one inch from the top of the pot. Stand the plant upright and lift into the middle of the new container. Wear thick gloves and get your hold on paper, not spikes. Use your repotting mix to partially fill the space between the root ball and the wall of the new container. Then wash the new soil into place with a steady stream of water. Add more prepared soil and water until the new soil is level with the top of the root ball.
    For large cacti, repotting will require several hours of intensive labor.

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It’s time to start onions and peppers

Onion and pepper seeds are slow to germinate and slow in their early stage of seedling growth. So if you’re growing them from seed, you want an early start. Now’s the time.
    Sow the seeds in a sterile potting mix rather than garden soil to avoid sprouting weeds and contaminating your seedlings with soil-borne diseases. Fill the pots a half-inch from the top. Tap the pot on a bench several times to eliminate air pockets. Firm the potting mix by pressing three or four fingers across the top of the mix. Sprinkle the seeds across the smooth surface, and lightly cover with fresh potting mix. Use a rose bulb or a fine sprinkler to lightly moisten the potting mix until you see water dripping from the bottom of the pot.
    Germinate these seeds in total darkness at constant temperatures of 75 to 80 degrees. How to get those conditions?
    Once excess water has drained from the bottom of the pot, cover the top with plastic and put it on top of the fridge or near the furnace where temperatures are relatively constant. Check the pots daily to make certain that the potting mix does not dry. Moisten accordingly.
    Onion plants grow in their original pots until it’s time to move them into the garden. Sow their seeds a quarter- to a half-inch apart to give them room to produce thick stems and larger root systems to better survive transplant. Sown closer than one-quarter inch apart, onion seeds will grow thin and spindly seedlings too weak to survive transplant in the garden. To accommodate a good population of seeds, use a six- to eight-inch diameter pot three to four inches deep.
    Pepper seeds can be sown closer together because you’ll transplant the individual seedlings into separate pots as soon as their true leaves appear. The first leaf-like growths are not leaves but cotyledons that provide energy for germination and early growth. Do not transplant the seedlings until you see true leaves.  
    Using a pencil or other object, lift each seedling from the potting mix. Grasp the seedling only by the cotyledon. Grabbing the stem or leaves may harm the plant, but the cotyledons are temporary and will separate from the plant under the shade of the leaves.
    To produce strong, healthy plants for your garden, transplant into four-inch pots in the same potting mix the seeds were sown in.
    Check the potting mix bag to see if it contains added nutrients. If nutrients have been added and if compost is part of the blend, water the pepper seedlings until the excess drips from the bottom of the pots.
    If the mix is free of nutrients or compost, add half the amount of water-soluble fertilizer recommended by the manufacturer. Fertilize at the full rate as soon as active growth begins.
    The amount of nutrients generally added to potting mixes is adequate for approximately one month. After that, use a liquid fertilizer as recommended by the manufacturer.
    Give the young the plants full sun. Check daily to maintain proper moisture.

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