May 1st, 2012
Grow Lights: Are They Worth the Cost?

In your article on starting seedlings indoors, you recommend using fluorescent shop lights with cool white or daylight tubes. Are we being duped into buying those expensive specialty bulbs or are there other benefits I am not aware of?

blog-dougNo, you’re not being duped. Fluorescent tubes that are designed for growing plants indoors work exactly as advertised, providing plants with the specific wavelengths of visible light they need for optimum growth. It’s up to you to decide if the incremental improvement in plant growth is worth the premium price you’ll pay for the tubes—three or four times the cost of standard tubes.

Natural sunlight provides the full “rainbow” of visible light, from red through violet. Plants use mainly the red, blue, and violet wavelengths to photosynthesize and grow. The manufacturers of grow lights design tubes to concentrate light production in the areas of the spectrum needed by plants. So if you want maximum growth and are willing to pay the price, you’ll get the best results from these specialized tubes.

But other fluorescent tubes also produce the wavelengths used by plants—just not quite as much. I have had excellent results growing seedlings under regular cool white or daylight tubes. I often mix the tubes in a single fixture—for example, one grow light tube, one daylight tube, and two cool white tubes in a four-tube shop light.

It’s also important to remember that fluorescent tubes produce less light as they age. When tubes begin to dim, move them to basement or garage fixtures, where the quality of light isn’t essential, and buy fresh tubes for your seedlings.  —Doug Hall

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April 24th, 2012
Daffodils Unbraided

After her daffodils were done blooming, my neighbor spent hours braiding their leaves into tidy bundles. I don’t have time for that. Am I hurting the bulbs by not braiding the leaves?

blog-dougJust the opposite. This is another example of the benefit of standing aside and letting nature do its job.

Think of leaves as solar collectors. Every bit of sunlight that falls on the leaves is transformed through the process of photosynthesis into carbohydrate reserves that are stored in the bulbs. The more photosynthesis, the more energy the bulbs stockpile, which results in a bigger floral display next year.

Anything that reduces the amount of sunlight reaching the bulb foliage will decrease next year’s flowering. This is true of all spring-flowering bulbs, not just daffodils. Your neighbor’s braiding technique, as well as the practice of bundling bulb foliage with rubber bands, won’t prevent the bulbs from returning but it certainly reduces the number and size of next year’s flowers. Even intermingling the bulbs with perennials, such as hostas and daylilies, so the bulb foliage disappears among the emerging perennials, will slightly reduce the bulbs’ future performance.

Allow the leaves to mature fully, until they’ve lost their green color, before clipping them off. Admittedly, tattered daffodil foliage that lingers into June is less than glamorous. In my garden, I operate under the theory that if there are dazzling flowers in another part of the garden in late spring—I recommend peonies, roses, bearded irises, clematis, and poppies—no one will notice the fading bulb foliage.  —Doug Hall

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April 17th, 2012
The Best Soil for Strawberries

My order of 50 bareroot strawberry plants will arrive at the end of April. The supplier recommends mixing 10-10-10 chemical fertilizer into the soil. Can you suggest an organic alternative? I have some horse manure, but it doesn’t appear to be fully rotted to use at this time.

blog-dougStrawberries grow best where the soil is fertile, well-drained, and amply enriched with organic matter. If you have been using compost, organic mulches, and cover crops in your garden for several years, you may need to do nothing further before planting the strawberries. A soil test will give you an accurate reading of how fertile your soil is.

If your soil falls short of the ideal, I recommend you dig in some organic amendments before you plant. Composted horse or steer manure is excellent for this purpose; it’s sufficiently composted when it looks and smells like soil. Yard-waste compost is another good source of nutrients and organic matter. Sphagnum peat moss as a soil amendment adds organic matter but little in the way of nutrients. Ideally, you should prepare the soil a few weeks before planting the strawberries.

Water thoroughly after planting, then give each plant one cup of a half-strength fish emulsion solution or compost tea to jump-start growth. Follow up 3 weeks later with another application if growth is slow.

Let your supply of fresh horse manure decompose longer before using it. You can layer it with leaves, kitchen scraps, and other garden debris to make compost, if you wish, or simply let it age in a pile. Next spring, use it to top-dress the strawberry bed when the plants begin to bloom.  —Doug Hall

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April 10th, 2012
A Child’s Garden of Learning

My granddaughter will be 4 this year. I am an avid vegetable gardener, and I want to share that passion with her. What’s the easiest vegetable for a child to grow?

blog-dougStart with radishes. The seeds germinate and grow quickly; they’re ready to eat in 30 days. On the chance she isn’t a radish fan, let her plant seeds of a few other vegetables that you know she likes to eat, like bush beans or leaf lettuce or snow peas.

Don’t forget to plant some flowers, too. Giant sunflowers are a kid favorite. When I was that age, I was intrigued by the exploding seed capsules of garden balsam. Zinnias and cosmos are great for bouquets and easy to grow from seed.

Books on gardening with children often stress the importance of choosing crops and flowers with big seeds, on the theory that they are easier for small fingers to grasp. But in my experience, kids do just fine with the tiny-seeded stuff, like lettuce and carrots. Seeds are cheap; let her learn by planting. Make your shared garden time informal and fun.

Your granddaughter is at an age when the world is filled with amazing discoveries. She’ll always remember the lessons about nature and life that she learns at your side.  —Doug Hall

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April 3rd, 2012
The Cause of Hollow Rose Canes

Something bored into the canes of my rose bushes last year, leaving hollow openings at the ends wherever I made a pruning cut. This spring I notice that a lot of those canes have died back. What’s doing it?

blog-dougThere are a number of species of bees and wasps that burrow into soft or dead wood to create nesting places to lay eggs and raise their young. These are solitary insects, not colonizers like honeybees. Although they usually seek out decaying wood to make their nests, the pithy heart of a rose cane is soft enough to invite their attention.

One species of burrowing bee is the leaf cutter bee, which leaves more obvious evidence of its presence in the dime-sized, semicircular holes cut into rose leaf edges. These bees are important pollinators, so while you might want to shoo them away from your roses, please don’t go about it by using anything toxic.

You can discourage bees and wasps from setting up household in your rose garden by dabbing a bit of grafting wax (buy it from an agricultural supply retailer) on each cut as you prune your roses, cut bouquets, or deadhead. Some rose gardeners report that a drop of white glue on each pruning cut also works—but it would have to be a type of glue that doesn’t wash away in the rain.

The damage from leaf cutter bees is usually insignificant and doesn’t compromise the plant’s health or vigor. You might decide that applying grafting wax—a messy and tedious task—is worse than simply pruning away the occasional damaged cane.  —Doug Hall

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March 27th, 2012
Invasion of the Rampant Vines

A new weed appeared in my garden in Raleigh two years ago. This spring I realized it’s seedlings from my sweet autumn clematis. I hate to give up this beautiful vine, but how else can I deal with the aggressive seedlings?

blog-dougSweet autumn clematis (Clematis terniflora) is a perennial vine of Asian origin. It climbs vigorously in a dense tangle of leaves and stems up to 30 feet tall. The blooms appear in August—fragrant masses of tiny white flowers—and are followed by feathery seed heads.

This is where the problem begins. The seeds blow far and wide, and by the following spring, clematis seedlings are popping up by the dozens. Sweet autumn clematis is on the invasive species lists of several states, mostly in the Southeast and mid-Atlantic regions. The Invasive Plant Atlas of the United States has mapped the problem areas on its website.

Prompt deadheading to prevent seed formation is one option. A more practical solution, however, is to replace Clematis terniflora in your garden with Clematis virginiana, a species that is native to the eastern half of North America. The two species are so similar in growth and appearance that they share a common name: virgin’s bower.

Clematis virginiana is also a rampant grower that will self-seed in your garden, although not as aggressively as Clematis terniflora. Most importantly, if any of its seeds blow into natural area, like a stream bank or woods, the resulting seedlings aren’t going to disrupt nature’s balance.  —Doug Hall

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March 20th, 2012
Battling a Sweaty Greenhouse

Last summer my wife and I added an attached greenhouse to the side of our house. When it is cold outside it sweats an awful lot. What can we do to eliminate (or at least minimize) this sweating? We do have a dehumidifier there that we use, but it doesn’t solve the problem.

blog-dougPlants constantly pump moisture into the air through their leaves—a process called transpiration. More moisture evaporates from the soil. For those of us whose homes become dry in winter, the extra humidity given off by a roomful of indoor plants is welcome. But when humid air comes into contact with a cold surface, like window glass, you get condensation.

Greenhouses are humid by nature. You don’t mention what types of plants are growing in your greenhouse, but because most plants prefer a humid environment, the moist air is probably doing more good than harm.

If drippy glass is an annoyance, you could try adding a second layer of glass, plastic film, bubble wrap, or polycarbonate sheeting inside your greenhouse. This added layer of insulation means you’ll get less condensation because the surface won’t be so cold. Add a fan, if you don’t already have one, to keep the air constantly moving. Raising the temperature in your greenhouse slightly will also help reduce condensation (but will increase your energy costs). When you’re watering, take care to not splash water on the benches, foliage, and floor.

These tactics will help somewhat, but in the end, you have to choose between dry glass and an environment that encourages plant growth.  —Doug Hall

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March 13th, 2012
Bricks in an Organic Garden

I want to build an organic herb and vegetable garden and was looking to edge it with brick. Can you please guide me on whether the bricks would leach toxins into the soil.

blog-dougA brick is as clean as the ingredients that went into its manufacture. Like terra-cotta pots, which are used by many organic gardeners, bricks are made from the soil itself—clay, in particular—and fired at extremely high temperatures to make them resist weathering. A typical modern brick is mostly clay with some sand and other minerals mixed in—nothing that would cause harm to an organic garden.

Still, there’s always a chance that a brick maker will introduce something toxic into the formula. If you’re buying new brick for your project, it’s worth calling the manufacturer and asking about its suitability for garden use. If you choose salvaged brick for the edging, make sure it hasn’t been contaminated with anything toxic—traces of lead-based paint, for example.

Personally, I have no qualms about using bricks in my garden.  —Doug Hall

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March 6th, 2012
Wood Ash as a Compost Ingredient

I’m not sure what to do with all my excess wood ash from the fireplace. I need to lower my soil pH, so I can’t add the ash to the garden or compost.

blog-dougThe ash from a wood-burning fireplace contains nutrients that plants need, including potassium, calcium, and trace amounts of zinc, magnesium, and phosphorus. But those nutrients come with a warning: Wood ash is strongly alkaline. If added to soil, it will raise the pH, or the measure of a soil’s acidity or alkalinity. Where the soil is too acidic (pH too low) and a higher pH would be beneficial, wood ash can be applied to lawns or gardens in place of agricultural lime to raise the pH. But if you are dealing with a neutral or alkaline (high pH) soil, adding wood ash would be a mistake.

The same goes for adding wood ash to a compost pile. Consider including wood ash as a compost ingredient only if the pile contains significant quantities of acidic materials, such as shredded oak leaves or pine needles. Even then, apply the ash with restraint, because too much can result in a loss of nitrogen from the compost. At a higher pH, the nitrogen present in the compost pile will escape to the air as ammonium hydroxide; if you smell ammonia near your compost pile, it’s losing nitrogen.

If you decide you shouldn’t use wood ash in your garden or compost, and you can’t find a farmer or gardener who can use it, I suggest you send the ash to a landfill with the rest of your household waste.  —Doug Hall

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February 28th, 2012
Growing Vegetables in the Wind

My wife and I are going to plant all our vegetables and herbs in planters on a back patio—the only place on our property with full sun. It’s also the windiest spot throughout the year. Are windy conditions bad for plants in containers, and if so, what should I do?

blog-dougHaving grown up on the wind-buffeted high plains of Kansas, I can tell you that it’s quite possible to grow vegetables in windy locations. In fact, good air circulation helps to discourage many fungal diseases. If it’s windy enough to tip pots over, just be sure you’ve chosen hefty, broad-bottomed containers and added a good dose of sand to the potting medium for weight.

Depending on the strength of the wind, you may need to change the way you grow your vegetables. The trick is to encourage a ground-hugging profile so the wind skims over their tops. Instead of staking tomatoes vertically or using tomato cages, let the vines sprawl on a bed of straw, or train them on low trellises that angle away from prevailing winds. Choose bush beans instead of pole beans. Let cucumbers and melons sprawl horizontally instead of growing them up a trellis.

Plants tend to dry out faster when it’s windy, so keep an eye on soil moisture. An automated drip irrigation system is easy to construct and will save time in the long run.

If your patio is so windy that leaves are shredded, then consider adding a barrier or screen of some sort to buffer the wind. Picket or lattice fencing or a leafy hedge on the garden’s upwind side will help to diminish the wind’s force.  —Doug Hall

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