Playing Around With Stems

Top Doggery

My pear trees look as if a giant spider went on a drunken frolic among the branches. Rather than fine silk spun in an orderly web, strings run vertically from branch to branch and branch to ground. Yet there is method in this madness. Mine.
 
As I spell out in my new book, The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden, plants produce a natural hormone, called auxin, at the tips of their stems or at high points along a downward curving stems. This hormone suppresses growth of side branches along the stem, allowing growth from a bud at the stem tip or high point be the “top dog,” that is, the most vigorous shoot.

Within any plant a push and pull goes on between fruiting an stem growth. Both require energy, which the plant has to apportion between the two. The more vigorously growing a stem, the less fruitful it is.

All this talk of hormones and inherent stem vigor is more than academic; it can translate into delicious fruits.

Pear trees tend to grow very vigorously, especially in their youth, with many vertically oriented branches. A certain amount of stem growth is, of course, desirable; leaves are needed for harvesting sunlight for energy and stems are needed on which to hang fruit.
Tied branches in British orchard

Tied branches in British orchard


But pear trees, especially in the youth, tend to put too much of their energies, too much for me, at least, into stem growth. The result is that they can take long time to settle down and begin bearing fruit.

Hence, the strings. I can change my pear trees’ habits by merely tying down branches, reducing the effect of that auxin so that growth is more uniform along a length of the stem. And, as important, slowing growth nudges the energy balance in the direction of fruiting.

Branch bending

The one branch on each young tree that I do not tie down is the main vertical stem, which is the still developing trunk off which grow the main side branches. I want this stem to keep growing upward. Also, I have to be careful not to create a downward arch when tying down any stem. You know why: a very vigorous shoot pops up from the high point in that arch.

More Fruit or More Growth?

Branch bending is not only for coaxing a tree into fruiting. On young branches, it creates a wide angle between a branch and the developing trunk. Wide angles here have been shown to result in good anchorage, sturdy side branches that can carry a weight of fruit.

Suppressing the vigor of side branches also ensures that they won’t compete with the developing trunk, which needs to be top dog.

And using string to play around with plant hormones isn’t needed on every fruit tree. At the other extreme from pear in its growth and fruiting habits is peach. Peach is naturally very fecund, and becomes naturally so at a very young age.

One reason for peach’s fecundity is that it bears all its flowers and fruits along stems that grew the previous season. Every year new stems grow that bear flowers and fruits.             

Beauty, Fruit, and Fun

All this concern with auxin, vigor, and fruiting comes most prominently into play with espalier, which is the training of a tree to an orderly, often two dimensional form. The tracery of the branches themselves adds to the decorative value of the plant.Pear espalier

Fruiting espaliers, besides being decorative, produce very high quality fruit. Pruning and branch bending maintain a  careful balance between yield and stem growth, and the form of the plant allows leaves and fruits to bathe in sunlight and air.

Asian pear espalier flowering

Bedding Down

Flat Beds

My vegetable garden is in beds. Your vegetable garden is in beds. Seems like just about everybody plants in beds these days. And with good reason. Beds make more efficient use of garden space. Soil compaction is avoided because planting, weeding, pruning, and harvesting can be done with feet in the paths. And the shapes of the beds can help make even a vegetable garden look prettier, especially with decorative plants edging the beds. 

Raised beds are also one way to grow happy plants in otherwise poorly drained ground, or in ground that has been contaminated by lead or arsenic. Such contamination is likely to occur from past use of leaded gasoline near roadways, from old paint near buildings, and from residual pesticides in sites that were once orchards.

My vegetable garden is laid out in 3-foot-wide beds with 18-inch-wide paths between them that feed into one 5-foot-wide path down the center of the garden. Many gardeners, when considering planting in beds, equate that with RAISED beds. My vegetable beds are not intended to be raised even a hair above the paths.My garden's beds

When I began my garden, I laid out the beds and covered them with compost, and then laid wood chips from local arborists in the paths. The difference in appearance of the two materials makes it easy to see where to walk and where not to walk. (For most people, that is. A well-known food writer once visited my garden. As I walked up a path, he tromped along next to me — right up the middle of the bed adjacent to the path! — until I let out a scream that brought him to an abrupt stop. Some lush plants in the bed were admittedly flopping onto the path, obscuring the difference between walking and planting areas.)

Raised Beds

Soil in raised beds is usually held there with boards or other edging. That edging material might itself be decorative: lumber, bricks, roof tiles, or, in a “colonial” garden, logs.Garden beds

Ideally, any wooden edging is rot resistant. Locust or redwood would be my top choices, but hard to get. “Manufactured” lumber, such as Trex, is another possibility. Then again, pine or spruce boards are readily available, relatively inexpensive, and should last quite a few years.

A six-inch-high bed provides enough well-drained root depth for pretty much all vegetable plants. 

One disadvantage to raised beds is that you have get soil to fill them up. That soil could, of course, come from what will be the paths. Metal edged raised bedsIf the area is wet, though, taking soil from paths is going to lower them, making them that much wetter.

Most people bring in soil for raised beds, and, in the interest of having the best possible garden, make that “soil” compost. Not a good idea. For one thing, compost is mostly “organic matter,” meaning compounds of carbon, hydrogen, and oxygen. With time, as organic matter decomposes to nourish soil microorganisms and plants, it disappears, literally, becoming carbon dioxide and water. So a raised bed filled with compost will eventually shrink down to almost nothing.

The thing to do is to fill beds almost to their brims with any any well-drained soil. Fertility is not important; that will come from the one to two inches of compost with which the soil is topped. Replenishing the compost each year will provide all the nutrition plants need for that year; no additional fertilizer is necessary. And no need to dig or rototill the compost into the ground.

One more thing about raised beds: The improved drainage also means that they dry out faster, so benefit from irrigation.

Table-like Beds, Not

If you were to walk into my garden, you might notice that my planting beds are indeed a bit higher than the paths. This was not deliberate.

Each year for many years I’ve topped all my beds and an inch or two of compost.Dog Sammy and garden beds Paths get replenished with wood chips only if they start to get weedy or bare soil starts peeking through.

If it weren’t for decomposition, those yearly additions of compost would have made each bed into a “table” more than three feet high. It hasn’t. Q.E.D.

An Onion Relative and a Cabbage Relative

 

Wild Leeks, Cultivated

I got pretty excited seeing rows of scrappy, green leaves emerging from the ground between a couple of my pawpaw trees. The leaves were those of ramps (Allium tricoccum, also commonly known as wild leeks) that I had first planted there two years ago, with an additional planting last year.Ramps

There’s no reason that ramps shouldn’t thrive here on the farmden; they’re native from Canada down to North Carolina and from the east coast as far west as Missouri. They’ve been best known in the southern Appalachian region, where festivals have long been held to celebrate the harvest.

Ramps became more widely known in the 1990s when, with the publication of a ramp recipe in Martha Stewart Living Magazine, the wilding became a foodie-food. Ramps are now threatened with being over harvested. Which, along with a desire to have this fresh-picked delicacy near the kitchen door, is the reason I planted them.

Large patches of ground in a forest preserve in New Jersey near to where a friend lives are blanketed each April with ramp greenery. We had dug up a few — very few — of the ramps, leaves and bulbs, which I transplanted here. Our harvest was not a threat to the ramp population. No one else has ever been seen harvesting there, and we dug up less than 1% of what was there. Research has shown that harvests are sustainable if no more than a different 5-10% of a planting are harvested yearly.

In the wild, ramps thrive in damp soil rich in organic matter in the shade of deciduous trees. My pawpaws provide the deciduous shade. The ground beneath those trees has been enriched each year for 20 years with a thick mulch of autumn leaves. To give the ground a further boost as far as organic matter and nutrients, I lay down a couple of inch thick blanket of compost over the bed last summer.

Over time, the bulbs should multiply and the plants further spread by self-seeding. I plan to harvest some seeds when they ripen in late summer to grow the seedlings under more controlled conditions.

The seeds have a double dormancy so they often don’t sprout until the second spring after ripening. The root dormancy, the result of immature embryos, is overcome with warmth and moisture. A warm autumn might be sufficient; if not, the next growing season. I plan to hurry the process along by potting up the seeds and keeping them warm (about 70°F) and moist for a couple of months. Then I’ll whisk the pot into the refrigerator to overcome the shoot dormancy, which requires a couple of months of cool, moist conditions, to jolt them awake. (More about natural blocks to seed germination in my new book The Ever Curious Gardener: Using a Little Natural Science for a Lot Better Garden.) The seedlings, as might be expected given their natural habitat, grow best with some shade — 30% shade to be exact, according to research.

Ramps are among the few perennial vegetables I grow. They are spring ephemerals, so in just a few weeks, their leaves will dissolve into the ground as the plants go dormant, to return again each spring for my dining pleasure.

A Different “Kale”

Seakale (Crambe maritima) is yet another perennial vegetable that I grow. It’s a cabbage relative that just now is sending up sprouts from its thickened roots. As soon as I noticed the sprouts, I covered the plants with an overturned, clay flowerpot, covering the drainage hole with a saucer to prevent light from reaching the plant.

Seakale tastes best blanched, that is, with its shoots grown in darkness. Under such conditions, leaves stretch out and grow pale and tender. In light, the taste of the leaves is too sharp. Or so I’ve read: Although I’ve grown seakale for many years, I wanted the roots to build up enough energy reserves to fuel new growth in the dark. This year, I will taste seakale.

Seakale will continue to earn a place in my garden even if its flavor falls flat (or sharp) because it’s a beautiful plant. Once released from the dark, new leaves emerge silvery green, large, and wavy. And then, later on in summer, foaming sprays of small white flowers emerge from within the whorl of leaves.

Expect a report on my take of seakale flavor in a couple of weeks, which is the time required for blanching. Like other perennial vegetables, once the harvest period ends, plants need to grow unfettered for the rest of summer to replenish the stored energy they spent fueling spring growth. 

 

Spring?

Spring, You’re Late

Seems like everyone — in the northern half of the country east of the Rockies, at least — is talking about this spring’s weather. Robert Frost (in “Two Tramps in Mud Time”) had it right when he wrote: 

The sun was warm but the wind was chill.
You know how it is with an April day
When the sun is out and the wind is still,
You’re one month on in the middle of May.
But if you so much as dare to speak,
A cloud comes over the sunlit arch,
A wind comes off a frozen peak,
And you’re two months back in the middle of March.” 

Perhaps T. S. Elliot (in “The Waste Land”) was right in writing that “April is the cruelest month.”

But has this past April really been crueler than most? Usually I pooh-pooh day to day impressions. But even Sammy, who usually bounds over to me from his doghouse each morning when he sees me, stayed in and watched as I crossed the yard a couple of weeks ago over ground recently covered with a dusting of snow. Sammy, the dog, and snow

Phenology, the study of climate as reflected in the natural cycles of plants and animals, is one way to give the weather an objective assessment. For decades, I’ve recorded the dates on which various plants have blossomed. My interest was horticultural: In spring, plants blossom after experiencing a certain accumulation of warm temperatures. So various blossoms can be indicators of when it’s safe to sow seeds or set out plants of various vegetables and flowers. 

Depending on late winter and spring weather, blossoming dates for various plants can vary quite a bit. Microclimate also plays a role, so I’ve tried to always note blossoming on the same plant from year to year. Back in 2010, forsythia bloomed about April 1st, the earliest I’ve ever recorded. Contrast that with 2009, when it bloomed about April 15th, or back in 1984, when it bloomed on April 25th!

This year, forsythia bloomed on April 23rd, late again. Over the years, forsythia bloom dates average around the middle of April, so this year is definitely late. All these forsythia bloom dates are for forsythia on my farmden, which is in a local cold pocket so blossoms spread their yellow petals a few days later than plants even just a few miles away.

Another key indicator for me is cornelian cherry (Cornus mas), whose yellow blossoms are most welcome because they frequently open the first day of spring. Not this year though; mine bloomed on April 20th.

Daffodils typically bloom here in early April, although back in 2016, they bloomed on March 25th. This year, April 21st.

One of my favorite blooming shrubs, also producing very tasty fruit, is Nanking cherry (Prunus tomentosa).

Nanking cherry hedge

Nanking cherry hedge

Stems on the row of them along my driveway typically form a veritable wave of pinkish white blossoms around the middle of April. As I write, it’s April 24th and that wave is just building. If warm weather continues, it should roll in within a few days. (Update: It did, on the 28th.)

Plants Tell Me When To Plant

It’s tradition to plant corn when “oak leaves are the size of mouse ears.” Considering phenology, I take timing one step further, planting, for example, lettuce seeds

Setting out onion transplants

Setting out onion transplants

when forsythias blossom, cabbage transplants when apples blossom, and — this is a tough one — peas a week BEFORE forsythias blossom.

So yes, it has been a “cruel” spring, if you’re wanting some warmth and sun. Then again, this cool weather has retarded, so far at least, blossom development of my fruit trees, which is a good thing. The later these trees blossom, the less chance for the open flowers to be burned by subsequent frosts.

Peas, Where Are You?

The downside to this atypically cool spring weather is that it has delayed planting of annual vegetables and flowers, or their growth if they’s already been planted. I sowed peas, as I always do, on April 1st. Still no sign of the poking up through the ground. I’m going to go outside, scratch around in one of the pea rows, and check if the seeds have either sprouted or rotted.

I’m back. The peas are okay, their first bits of green are peeking up through the surface of the ground.

No matter if the season is unseasonably cool or warm, by this time of year the progression of blossoms provides a feast for the eyes and the nose.

Plant sale in June . . .

Plant sale web ad, 2018

(Micro)climate Change

As the train rolled southbound along the east bank of the Hudson River, I took in the varied landscapes along the opposite west bank. Spilling down the slope to the river on that bank at one point was what appeared, from a distance, to be a vineyard. I was envious.

(I never could understand why the region here is called the Hudson Valley. Along much of the Hudson, the land rises steeply right up from river’s edge. Where’s the valley?)

I wasn’t envious of the riverfront site of the vineyard property. I wasn’t even envious of having a whole vineyard  of grapes. (I cultivate about a dozen vines.)

What I did envy was the microclimate of the site. Microclimates are pockets of air and soil that are colder, warmer, more or less windy, even more or less humid than the general climate, due to such influences as slopes, walls, and pavement. 

The vineyard was not that far from my home, but the microclimate was worlds apart. Every parcel of land, from a forty-acre farm field to a quarter acre lot, will have some microclimates, and siting plants with this in mind can spell the difference between whether or not they thrive or even survive. Microclimate, early tulipsI’m banking, for instance, on the slightly warmer temperatures near the wall of my house to get my stewartia tree, which is borderline hardy here, through our winters. (It has.) And I expect spring to arrive early each year, with a colorful blaze of tulips, in the bed pressed up against the south side of my house. Proximity to paving also warms things up a bit.

Microclimate for cold, microclimate for warmth

Microclimate isn’t always about trying to keep a plant warmer in winter, or speeding up growth in spring. It’s also useful for keeping plants cooler. By training my hardy kiwifruit (Actinidia spp.) vines right up against the shaded, north sides of their hefty supports, I keep the sun off their trunks in winter and avoid the splitting that occurs when trunks are warmed during winter days, then precipitously cooled as the winter sun drops below the horizon. Microclimate, lingering snowBy planting the coveted blue poppy in a bed on the east side of my house, I hoped to give the plant the summer coolness that it demands. (That east bed was still too sultry; the plants collapsed, dead.)

Microclimates are important when growing fruit plants that blossom early in the season because frozen blossoms do not go on to become fruits. Early season bloomers need microclimates that are slow to warm up.

South facing slopes stare full face at the sun, so these slopes warm up early in spring and are warmer in both summer and winter. Therefore, a south facing slope—even if the grade is only slight—can be used to hasten fruit ripening on a plant like persimmon, which blooms late but needs a long season when grown near its northern limits.

Right after I push soil over the first seeds of sweet corn that I plant, I firm it over that hole with my foot at an angle to make a south-facing depression in the ground. That mini-slope will warm up just a wee bit sooner than flat ground.

The sun glances off north slopes, delaying their warming in spring and keeping them cooler in summer. Such a microclimate is ideal for an early blooming fruit tree like apricot or peach, and for plants, such as sweet peas, that enjoy cool summer weather. Likewise ideal for such plants is near the north side of a building, where shade remains through winter and the early part of the growing season.

If a slope actually has some elevation to it, the air is going to cool by one degree Fahrenheit every three-hundred feet going up the slope. If I had sloping ground, which I don’t, and sought a cooler location for planting, I’d avoid planting at the very top of the slope, though, because the upper reaches are usually windy.

A cold spot, here

Ideal vineyard site, from plant perspective, in Germany

Counterintuitively, the very bottom of a slope will also be a cooler microclimate. On nights when the sky is clear, with no clouds or leafy trees to block re-radiation of the sun’s heat from the ground back to the heavens, the air at ground level cools. An “inversion” occurs, with warmer air higher up. The cold air, which is denser than warm air, flows downhill to settle into depressions, just as a liquid flows downhill. A low point would be the worst possible location for planting strawberries, which grow near ground level and whose early blossoms are threatened by late frosts in spring. Any dense fence or shrubbery on a slope stops the downward flow of cold air, which will pool, just as dammed water would, near the upper side of the barrier.

Among the fruits I grow are apples, peaches, plums, and pears, all of which tend to bloom early. My site, unfortunately, is just about the worst possible site for growing these fruits. Apple blossomsThe cold air that settles here on clear spring nights increases the likelihood of late frosts and also causes moisture to condense on the plants, leaving them more susceptible to disease. Hence my envy for that sloping vineyard site.

Check out my new book, The Ever Curious Gardener, for more on microclimate!!