May 21, 2009

For a day every week or so, my yard smells like salad dressing. No, I’m not getting the lettuce dressed while it’s still out in the garden. Yes, that smell is vinegar. For the past few years, regular strength vinegar, straight up, has provided nontoxic (except to sprayed weeds), sustainable, “green” weed control on the edges of beds, in paths, and on my brick terrace.

I specify “regular strength” vinegar because our USDA has also been looking into vinegar as weedkiller. On the theory that if a little of something is good, a lot must be better, USDA research focuses on using more concentrated solutions of vinegar – even 20%. Those more concentrated solutions are more effective but you have to be very careful using that stuff. It burns. I’ll stick with salad dressing strength 6% solution.

A couple of benign additions increase the power of my “regular strength” vinegar. First comes vegetable oil – no, not salad dressing again, but to helps the vinegar stick to weeds’ leaves. I use 2 tablespoons of canola oil per gallon of vinegar. Then comes soap, specifically Ivory liquid detergent, 1 tablespoon per gallon, to better spread the vinegar and oil over the leaves.

This mix only kills greenery so needs to be applied regularly to starve roots. Hence my repeated applications.

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It’s amazing how many seedlings you can grow in a small space using a Speedling or some other multi-cell plastic (or “plug”) tray. These trays are re-usable, with tapered cells each about an inch square. For example, a 1 foot by 8 inches area was home to my 54 zinnia seedlings. The tapered design allows for good root development and, if the trays are elevated on a screen, the roots stay in bounds by being air-pruned as they try to exit the bottom hole.

I had 54 zinnias, 54 Signet marigolds (ferny, lemon-scented foliage and small, yellow flowers), and a slew of other flowers that I had sowed a month and a half ago in the enthusiasm of spring. A few days ago, the time came to figure out just where to plant all those seedlings. Flowers generally look best when planted out in large masses rather in isolation or anemic strips, so with this many plants, it’s hard to go wrong.

Planting is quick with plug trays. The seedlings were at just the right stage for transplanting, so all I had to do was yank on each stem to pop out a whole plant, root and all. A quick poke of my trowel into the ground was all that was needed to make a home for each seedling. Firming the soil around each plant after dropping it into its waiting home completed the planting . . . except for watering. That watering was thankfully supplied by the inch-and-a-half of rain that followed my planting.

Small plants establish more quickly than large plants, and with less care, so I’m finished with these plants except to enjoy their flowers.

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I must have a built-in temperature sensor in my head. Last night (May 18^th) my eyes sprung wide open at 1:38 a.m., I walked over to my remote thermometer, and saw that the temperature had just reached that magic number of 32 degrees Fahrenheit. The sky was clear and the morning was, to say the least, early, so I guessed that the mercury would dip even lower.

Preparations had already been made for a light frost, but who knew just how cold temperatures might plummet? After all, last year at about this time, a sunny morning greeted me with leaves blackened by a severe freeze. So I got dressed and threw any coverings I could find over any plants that could be protected and needed to be. Key lime, pomegranates, lemon trees, and other potted, tender plants went into the garage. Nothing could be done about the blossoming hardy kiwifruit vines, the soon to blossom grapes, and the fruitlets already developing on apples, pears, and pawpaws.

I went back to sleep.

Morning saw the thermometer reading 28 degrees, hoary frost on the lawn, and a sunny day in the offing. Damage assessment would have to wait until the sun melted frost off everything. And the damage, assessed this morning at 9:30, was  . . . . zip, nil, nein, nada, rien, nothing. It’s amazing the way even tender plants, like those marigolds and zinnias I had planted (and had not protected because there were too many of them), toughen up after a few days outside. It looks like a good year for fruit – unless we get another, more serious, freeze.

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Of Poppies, Snow, & Herbicides

Oriental poppies, now in bloom with large, floppy, flaming red blossoms, are worth ooh-ing and ah-ing about. Likewise for Snow in Summer (Cerastium tomentosum), with small gray-green leaves and small white flowers, except that too few people know or grow this plant.  Here, the two plants look especially congenial together with Snow in Summer hugging the ground at the feet of the poppies and spilling over the rock wall that supports the bed in which these plants grow.

No skill is needed to grow Snow in Summer, or to propagate it. Plant it and it will spread, rooting as it creeps but never with frightening speed.

Alas, the show from either plant is all too transient. Poppy foliage is soon to yellow and melt slowly back into the ground. And by the time you read this, blossoms of Snow in Summer will have tapered off and its leaves will have lost their exuberance of spring. The show’s transience makes it all the more appreciated.

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A narrow, yellow strip of vegetation -- dead vegetation --  sits at the bottom of the rock wall supporting the poppy and Snow in Summer bed (also home to espaliered pears, rugose rose, alliums, and other perennials) and at the its upper border with lawn. I can’t say that I’m proud of the yellowing strips of lawn and weeds, but the weedkiller I applied is very effective at keeping errant weeds and grass out of beds, paths, from climbing the rock wall and growing in between bricks of my terrace, and away from the bases of young trees. Weedkiller??!!

Yes, I am spraying weedkiller . . . but the weedkiller I’m spraying is very benign. I take straight household vinegar, which is 5 to 6 percent acetic acid, and add to it, per gallon, 2 tablespoons of canola oil and 1 tablespoon of dish detergent. The detergent and oil help the vinegar spread out on and stick to the leaves.

The USDA also has been researching the use of acetic acid as an organic spray to control weeds. They found 20 percent acetic acid to be very effective, which is not surprising. Twenty percent acetic acid, though, is neither very safe to use nor readily available.

My vinegar concoction, at 5 to 6 percent acetic acid, is, of course, not as effective as the USDA’s 20 percent. Nor is it nearly as effective as the widely used chemical weedkiller Roundup. My mix only kills green leaves; Roundup is translocated throughout a plant to kill roots, stems, and leaves. Plants store energy in roots and stems so can recover from my spray to grow new leaves. Eventually, with repeated spraying, vinegar-sprayed weeds run out of energy and die. Plus, my mix is not much different from salad dressing (except that it would need more oil, some herbs, and no detergent).

My aim is to spray frequently enough to kill each emerging round of greenery while it’s still drawing on energy reserves, before the leaves start socking away excess energy in roots and stems. Early in the season weekly sprays are needed; later, every two weeks or so.

Because vinegar only kills greenery by direct hit, it is most effective on smaller weeds where there is no “shadow effect.” The vinegar spray’s effectiveness drops at temperatures below 70° F.

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My farmden necessitates the application of about 8 gallons of vinegar mix per session, most easily applied using a backpack sprayer. Mixing up and spraying the mix is no fun but has become less unenjoyable with my new Jatco sprayer.

Anyone who has used a backpack sprayer will appreciate Jatco’s rather unique qualities: a carrying handle, clips for holding the pumping lever and spray wand during storage or carrying, a large mouth for easy filling and cleaning, a mixing paddle that moves with each pump of the handle, and the totally internal pump that eliminates that awful sensation of spray material dripping down your lower back (even if it is just vinegar). The sprayer is almost perfect, two very minor shortcomings being the difficult-to-read volume indicator embossed on the tank and the lack of a bottom handle to grab when inverting the sprayer when cleaning it.

The best thing about the Jatco sprayer is the good leverage afforded by the way the pump handle is connected to the pump. Less pumping means less work. Carrying 3 or 4 gallons of liquid on your back in the hot sun is work enough.

Propagating Cuttings, Quackgrass

Ten weeks ago I wrote of the “pot in pot” propagator that I was using to root dormant fig and mulberry cuttings. The propagator is nothing more than a small, porous, clay pot filled with water and with its drainage hole plugged that I plunged into the mix of peat moss and perlite that filled the larger pot. Water drawn out of the small pot keeps the peat-perlite rooting mix consistently moist.

The cuttings have sprouted with enthusiasm. And when I lift out the small pot, I see roots running around in the moist rooting mix, so I separated the plants and potted them up individually.

No need to put the propagator away now that plants are no longer dormant. With a simple covering to maintain humidity, the propagator also works well for so-called softwood cuttings, that is, cuttings that start out with leafy shoots. Technically, today’s new cuttings aren’t “softwood” because they haven’t had time yet to begin much growth. They could more accurately be called “leafy.” Their first leaves have unfolded and shoots (the “softwood”) are soon to appear. Whether “leafy” or “softwood,” such cuttings need high humidity to keep leaves from wilting until roots develop.

The propagator conversion involves nothing more than poking four sticks into the rooting medium equally spaced around its outer edge, and then draping a plastic bag over the sticks. Bright light will keep the green leaves feeding the cuttings. Direct light is a no-no because it would cook the cuttings in their high humidity chamber.

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I suppose I could be nostalgic about the quackgrass (Elytrigia repens, and also commonly called witchgrass and couchgrass) stealthily making inroads into my various gardens. After all, quackgrass was my first serious weed problem in my first real garden, a vegetable plot of about 500 square feet in Madison, Wisconsin. At the time, the lakes in Madison were suffering their own weed problems, the result of “fertilization” of the water with runoff from over-fertilized, residential lawns surrounding the lakes. Giant beaters plied the lakes in those days, chopping the lake weeds which were then harvested onto boats and then trucks for disposal. “Weed-free mulch!,” thought I. 

I convinced a lake weed crew to dump a truckload of those water weeds onto my front lawn. I spread the mulch quickly -- I had to because the soggy mass started rotting within a few hours to what was beginning to smell like a a pig farm. Laying pitchfork after pitchfork of the stuff between rows of vegetables spelled quick death to the quackgrass.

My gardens now are far more extensive, no straight expanses beckon easy mulching, and water weeds are not in the offing. So for now, I am attacking quackgrass mano a mano, digging and pulling out every last shoot that I can find along with attached, running roots -- no easy task among perennial flowers. Where I can, I’ll spread a few sheets of newspaper and top that with mulch. Now is the time to attack because in about a month, new runners will begin to push further afield just beneath the soil surface. The pointed ends of these runners are sharp enough to push right through a potato.

Quackgrass is so widespread that you’d think it was native. Not so. But it has been here for a long time, coming over from Europe with the first colonists. And it’s not all bad: It is good forage for horses and cows, and has been used in herbal medicine especially for kidney ailments. “It openeth the stoppings of the liver,” according to 16th century herbalist John Gerard. Still, it’s not welcome in my garden.

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I’ve got one more deathly arrow in my quiver with which to fight off quackgrass, but it must wait until the weather warms. Vinegar. Household strength vinegar sprayed on the plants kills the leaves; repeatedly killing the leaves eventually kills the plants. I boost vinegar’s efficacy by pouring 1 tablespoon of Ivory dish detergent and 2 tablespoons of canola oil into each gallon of vinegar. Vinegar works best when temperatures rise above 70° F.

THINGS NOT SO ROSEY

Lest anyone believe that everything is always rosy here on the farmden, it ain’t so. True, right now, vegetable beds are brimming over with crisp, tender heads of delicious lettuce, broccoli, endive, and cabbage, and upright stalks of aromatic celery and leek. And, yes, the floor of the greenhouse is verdant with developing, young lettuce, large, leafy kale and Swiss chard plants, and 10 foot tall fig trees bearing fruits

But let’s start with those figs, three different varieties of which live with their roots right in the ground in the greenhouse. Green Ischia has been bearing large, copper-colored, firm, sweet fruits for weeks and weeks. No problem here.

About 8 feet from the Green Ischia grows a Brown Turkey fig. It kicked off the season as usual, loaded with fruit that started ripening in early September. Then scale insects moved in, dotting stems and eventually the fruits with their gray bodies, and sucking the life out of everything until the harvest petered away to almost nothing

About 8 feet from the Brown Turkey tree grows another fig tree, Kadota, with fruits lined up along its stems also. From past experience, I expected problems with Kadota. It’s a delectable and heavy yielder that thrives in hot, dry climates. The greenhouse is hot but hardly dry. With the high humidity in there, almost every Kadota fig has turned to a fuzzy, white ball just before ripening.

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The Kadota problem is the one most easily solved. That white fuzz is fungal, and the fungal culprit is probably Botrytis cinerea, a cosmopolitan fungus boasting a slew of host plants. Botrytis claims credit, for example, for a wet spring’s fuzzy, gray strawberries, for a wet summer’s fuzzy, gray raspberries, and, in a more benevolent form, for “noble rot” of grapes, which makes for a sought-after wine. All sorts of ominous chemicals can control botrytis. More benignly, on stored fruits at least, it has been controlled with a 1% solution of baking soda, or an atmosphere of either 15 ppm acetic acid (i.e. vinegar) or 75 ppm cinnamaldehyde, the natural flavoring of cinnamon

Trying to control disease on my Kadota figs with sprays would be an uphill battle considering the perfect conditions for botrytis: a very susceptible variety of fig, a very humid environment, and presence of the fungus. My approach is straightforward, and that is to dig up Kadota and plant a more disease-resistant variety in its place

On to Brown Turkey . . . Scale insects get up into plants and move around with the help of ants. Stopping the ants goes a long way to putting the brakes on scale. Stopping the ants is easy: Masking tape wrapped around the trunk and coated with a continuous ring of sticky Tanglefoot Tangle-Trap Insect Trap Coating. I also, of course, have to make sure there are no leafy, stemmy, or other bridges around which ants can detour. Next year

One other possibility for reining in scale insects is to spray “summer oil” in spring after the plants have leafed out and greenhouse beds are clear of lettuce, kale, and other vegetables. Summer oil is highly refined so as not to damage plants while it’s smothering the scale insects.

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Another problem I notice in the greenhouse is that developing lettuce heads have some hole-y leaves and a few gobs of insect poop. Slugs are the usual, occasional problem in my greenhouse, but they don’t leave green, gobby, poopy calling cards. (No less unpleasant are the silvery trails they do leave, from their dried slime.) With more than usual grasshoppers this year, that was also a possibility. Nix on that. I just haven’t seen enough of them for all that poop, and they chew beginning at the edges of leaves. Attacked lettuce leaves were pocked with holes

The feeding resembles the handiwork of cabbageworms or cabbage loopers. They’ve never before indicated a liking for my lettuce but are known to include lettuce in their diet. Yet another possibility is another caterpillar, armyworm. This one feeds at night and, because I haven’t seen any caterpillars, is now the most likely culprit

The natural insecticide, Bt (sold under such trade names as Dipel and Thuricide), that I mentioned last week is very effective against the cabbageworms and loopers, as well as young armyworms. Larger armyworms are finished or just about finished feeding anyway.

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These few problems notwithstanding, things are still rose-y, or at least carnation-y, in the greenhouse. The big, fat, fragrant ‘Enfant de Nice’ carnations that I grew this summer . . . well, I couldn’t just leave them out to die from cold. So I dug up some plants to grow in the greenhouse. They add a nice spot of red, white, or pink color, and the fragrance is, as billed, “intoxicating spicy-sweet clove.”

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Hot weather and rampant plant growth prompt me to add a word to the traditional English round, “Sumer is icumen in, Lhude sing cuccu!” My new version is “Sumer weeds is icumen in, Lhude sing cuccu!” (“Summer weeds have arrived, Loudly sing, Cuckoo!”)

Almost overnight, big clumps of barnyard grass (Echinochloa crus-galli) have appeared in joints of the flagstone path leading up to my front door. It seems that just a week ago, a combination of hand pulling, weed whacking, and vinegar sprays had those joints free of everything except for a bit of moss. Today I had to cut clumps out with a bread knife that was useless on bread but has proved very useful for in the garden.

Besides being unsightly, those clumps of barnyard grass are unwelcome because they’re spreading. The stems prostrate stems root wherever they touch bare ground. And the emerging seed heads are prolific seed producers – reportedly over 300,000 seeds per square yard.

You might think I should relax because barnyard grass is an annual that flops down dead with the first autumn frost. But all those seeds are going to sit in the soil, some germinating next spring, some the following spring, and on and on. Another of the plant’s common names says it all: panic-grass.

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Purslane is another summer weed that’s picked up steam in the past few weeks. The problem with purslane is that you can’t just pull it out and toss it on the ground. The succulent leaves and stems are very resistant to drought, staying plumped up with water even when detached from the roots. Stems and leaves left on the ground take root and become whole, new plants.

A recent meal at a fancy restaurant in New York City solved the purslane problem. I’d always known purslane to be edible but the taste and texture never appealed to me. I thought I’d give purslane another try in the form of the beet, goat cheese, and purslane salad listed on the menu.

The salad was delicious, so for the next dinner at home we weeded and harvested at the same time, on the same plant: purslane. As a matter of fact, the garden seemed to be lacking in sufficient purslane to meet our new found needs. I’m not yet ready to start sowing purslane seed, which you can actually purchase. We’ll just harvest more conservatively.

For all I knew, the purslane in that restaurant salad might have been harvested from cracks in sunny pavement behind the restaurant.

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For gustatory use, purslane shouldn’t be confused with another, similarly prostrate plant , spotted spurge, about which I wrote a year ago. Stems and leaves of spotted spurge are not succulent. Like other members of the spurge family, spotted spurge exudes a toxic, milky sap when injured.

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Yellow threads weaving up, down, and all around clumps of blackberry, dock, and other wild plants along a road recently caught my eye. These threads are the stems of a most interesting summer weed: dodder (Cuscuta spp.)

The reason dodder is yellow and, incidentally, leafless is because it has no chlorophyll. How does it make food, then? It doesn’t! Dodder is a parasitic plant.

Dodder seeds germinate and the plant’s roots enter the soil only long enough to support a few inches of stem growth. Once young dodder grows a few inches tall and comes in contact with a potential plant victim, it inserts a modified root right into the plant. The grounded dodder root dies and the remaining dodder plant spends summer sucking nutrients and carbohydrates from its host plant, offering nothing in return.

Dodder is a very effective weed. It makes many seeds each season, the seeds do not germinate all at once, some waiting years before germinating, and it has a wide range of plant hosts. Like barnyard grass, purslane, and spotted spurge, the first frost of autumn kills the plant. Not the seeds, though.