Note 1: I have some plants leftover from this past weekend’s  plant sale here at the farmden. Contact me by June 24, 2022 if you’re interested in purchasing to pick up any white currant, black currant, fig, or gooseberry plants (a number of varieties of the latter two).They’re all discounted at 25% off.

Note 2: My farmden is open for a Garden Conservancy Open Day on Saturday, June 18, 2022 from 2 p.m. to 5 p.m. Registration is required, here.  

Shoots versus Fruits

I’ve been playing around with the orientation of some of my trees’ branches to influence how they grow. Branches pointed skyward generally are inherently vigorous, giving rise to long shoots, especially from their topmost buds. At the other extreme are branches oriented horizontally. They’re generally weak-growing, and tend to produce fruit buds rather than vigorous shoots and leaves. The cool thing is that if you or I change branch orientation, it changes the growth and fruiting habit of that branch.

Bending and tying branches is a good way to balance shoot growth and fruiting, especially of apple and pear trees. Both types of growth are needed. The fruits for us to eat, and the shoots to “feed” the fruit and to provide places on which to hang the fruits. Shoot growth is also needed to periodically replace old wood.

Pear espalierBranch bending to regulate growth and fruiting is especially evident with an espalier, which is a tree grown in an orderly, usually two dimensional form. Lurking behind the many forms, fanciful and otherwise, for espaliers is an appreciation for their effects on growth and fruiting.

Achieving Balance

Backyard apple and pear trees commonly put too much of their energy into shoot growth, a problem that can be exacerbated by overly enthusiastic pruning and over-fertilization. One way to coax an overly vigorous tree into bearing is by pulling upright branches downward, affixing them in that direction. This may seem an unnatural way to treat a plant, but it does help a tree to get started fruiting. Once fruiting begins, the weight of the fruit will keep branches down.Tied branches in British orchard

Sometimes fruit pulls a branch down so much that it’s too fruitful and needs invigoration. Asian pears are prone to bearing too heavily too early in their life, especially if grafted on dwarfing rootstocks; the result is a stunted tree. The cure is to drastically cut drooping branches back to more upward growing — and, hence, vigorous — side shoots. Or to stake branches into more upright positions.

Bending down branches spreads them, which, along with correct pruning, also lets all branches bathe in sunlight. With many upright growing branches, the interior of a tree becomes too shaded to produce fruit buds or even leaves. Well-trained cherry tree

Branches that are spread at an early age make wide angles with the trunk. That wide angle attachment becomes a strong juncture, one that will not break when eventually weighted down with fruit, as often occurs with branches having narrow crotch angles.

Practical Matters: How to Do It

On very young trees which are still forming their main branches around the trunk, I start spreading the new shoots when they are just a few inches long. After bending a shoot carefully so as not to break it, I hold it in that position by snapping a spring-type clothespin on the trunk with the tail of the clothespin holding the shoot down. training with clothespinAnother way to hold this wide angle is to press one end of a toothpick into the shoot and the other into the trunk, just enough to keep the toothpick in place.

For older branches, I use either a stiff wire or a length of wood with a brad driven in each end. (I’ve previously removed the brad’s head and sharpened what remains.) Wooden branch spreaderTying a string around a branch, and then to a weight on the ground or to the tree’s trunk is another way to pull a branch down. Or, you can affix a weight right to the branch. For instance, glue a clothespin to a rock, then clip it to the branch.Training with branch weight

After a few weeks, the ties or weights or clothespins can be removed. The branches will stay in place.

Ideally, re-orienting the branches of apple and pear trees achieves a favorable balance between shoots and fruits. To this end, strive for about a sixty degree angle to the trunk. I try to keep the branch straight as it is oriented to this angle. If the branch has a bow in it when pulled down, overly vigorous shoots are apt to grow from buds at the topmost part of the bow.

Don’t expect immediate payback for all this care and effort. A year or more might elapse before an apple or a pear tree forms fruit buds, and fruit buds form fruit buds the season prior to actual fruit production. It’s worth the effort in the long term.Dwarf-apple-harvest

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


 Last Tomatoes & Peppers

   Late fall, and my thoughts turn naturally to . . . ethylene! You remember ethylene from high school chemistry. A simple hydrocarbon with 2 carbon atoms double-bonded together with 2 hydrogen atoms attached to each of the carbon’s remaining two free bonds. C2H4. It’s a gas, literally, and an important industrial chemical transmuted into such products as polyethylene trash bags, PVC plumbing pipes, and polystyrene packing “peanuts.”
    Oh, I forgot, this is supposed to be about plants. Ethylene is synthesized in plants and is a plant hormone with — as is characteristic of hormones — dramatic effects in small amounts.
    I think of ethylene as I sliced the last of the season’s fresh garden tomatoes for a sandwich a couple of weeks ago. Note that I wrote “fresh,” not “fresh-picked.” The tomatoes had been picked almost two months prior from vines I was cutting down and gathering up for composting. They sat on a tray in the kitchen, very gradually, over the weeks, morphing in color from light green to pale pink to deep red.

Tomatoes & peppers in November

Tomatoes & peppers in November

    Ethylene is responsible for this transformation from pale and insipid to red and flavorful (flavorful as compared with the pale green or pink stages, not as compared to vine-ripened summer tomatoes). It’s produced naturally in ripening fruits, and its very presence — even at concentrations as low as 0.001 percent — stimulates further ripening.
    The tomatoes shared the kitchen tray with peppers, peppers that also were green when laid on the tray. All ripening fruits produce ethylene, peppers included. So let a green pepper sit long enough and — as long as it is sufficiently mature and does not dry out too much, or rot — it will ripen red, or yellow or purple, whatever is its ripe color. Which mine did.

Yes, One Rotten Apple Does . . .

    The ethylene given off by a ripe apple or banana can be put to use in speeding up ripening of tomatoes. Just put either of these fruits into the bag with tomatoes. Apples and bananas are climacteric fruits which, instead of emanating a steady stream of ethylene, ramp up production dramatically as full ripeness nears.
    Among other effects, ethylene production itself stimulates further ethylene production. So if ripening fruits are left too long in a bag, ethylene stimulates ripening which stimulates more ethylene which stimulates more ripening, ad infinitum, until what is left is a bag of mushy, overripe fruit. Hence, one rotten apple really can spoil the whole barrel.

It’s a Gas for Fruiting Also

    Ripening isn’t the only prod to ethylene production in a plant. Stress also can do it, whether from the nibble of an insect, a disease spore wending its way through a plant’s cuticle, wind or snow bending a branch, or pruning shears trimming a wayward branch.
    Exogeneous ethylene leaves its mark on more than just promoting ripening. A century and a half ago, pineapple growers in the Azores saw that plants nearer outdoor fires flowered soonest. Plants that flower sooner, fruit sooner.
    If you’ve rooted a pineapple crown — relatively easy, just twist it off, plant in pot of well-drained potting soil, and water only when soil dries out — you can speed flowering and fruiting by setting an apple in the crown for a few days, then covering the plant with a bag.

And for Not Staking (Too Much)

    Soon, I’ll be going outside, pruning shears in hand, to put ethylene to use again. Ethylene also slows growth, in so doing coaxing flowering.

Flowers on bent pear branch

Flowers on bent pear branch

   Pear trees are famous for being slow to settle down to flowering and bearing fruit. No, I’m not planning to hang apples in the pear trees and enclose them in plastic bags! I am planning, after I finish working on the trees with my shears, to bend some well-placed branches to a near horizontal position, using weights, string, and pieces of wire to hold bent branches in place. The stress of bending — compression on one side of a stem, expansion on the opposite side — steps up ethylene production (30-300%), slowing growth, inducing flower bud formation, and shortening the time till I bite into my first pears from young trees.
Young tree, staked    I’m not yet finished with you ethylene. I planted a few new apple trees this year. They need staking, but not too much. Stakes should allow some movement of the developing trunks, and free movement of the top third of the plants. Movement causes the same stresses as branch bending, likewise inducing ethylene production. Ethylene, as you now know, slows growth but also, as you might not know, increases the thickness of the moving part; i.e. makes for a sturdier trunk. That’s what I want for my young trees.