Midsummer “To Do” List

Maintenance, Pruning

For many gardeners, spring is the critical gardening season, what with preparing the soil, starting seedlings, setting out transplants, pruning, watching and staying prepared for late frosts and . . .  In my view, right now is just as crucial, and for an equal number of reasons.

True, a 90 degree day with high humidity doesn’t exactly pull you out to the garden to putter around in blazing sunlight. But early mornings around here are mostly cool, calm, and beautiful.

Much of what needs to be done is regular maintenance. Pruning tomatoes, for instance.Tomatoes, staked, July I train my tomato plants to stakes and single stems, which allows me to set plants only 18 inches apart and harvest lots of fruit by utilizing the third dimension: up. At least weekly, I snap (if early morning, when shoots are turgid) or prune (later in the day, when shoots are flaccid) off all suckers and tie the main stems to their metal conduit supports.

Espalier is the training of trees to two dimensions whereby the tracery of the stems is as decorative a plant feature as are the leaves, flowers, and/or fruits. To maintain that tracery of branches, my espaliered Asian pears need frequent pruning. Espalier Asian pearI lop wayward shoots either right back to their origin or, in hope of their forming “spurs” on which will hang future fruits, back to the whorl of leaves near the bases of the shoots.

The response of the pear trees depends on the weather, which is unpredictable. Dry sunny weather is conducive to spurs. Rainy weather coaxes, instead, new shoots pop out right where I cut back old shoots. I think.

Maintenance, Water

Whether or not the weather is dry, rampant growing plants quickly suck the soil dry. So I also keep attentive to watering this time of year. The vegetable garden and potted plants are the neediest in this respect; fortunately, they demand little from me to do because a timer turns its drip irrigation system on and off automatically. All I have to do is to periodically check to make sure drippers are all dripping. Drip tubes to potted plantsNewly planted trees and shrubs are another story. This first year, while their roots are spreading out in the ground, is critical for them. I make a list of these plants each spring and then water them weekly by hand all summer long unless the skies do the job for me (as measured in a rain gauge because what seems like a heavy rainfall often has dropped surprisingly little water).

A one-inch depth of water is needed to wet a soil about a half a foot deep. I provide this with 3/4 gallon of water per estimated square foot spread of the roots.

Fall preps

Sowing seeds and setting out transplants isn’t only a spring gardening activity. Tomatoes, peppers, eggplants, cucumbers, and other summer vegetables peter out during the shorter, cooler days of late summer and early fall. But there are plenty of vegetables that enjoy growing conditions that time of year.

Some of the fall vegetables need to be sown now to be large enough to mature in fall. No need to provide space for them by digging out tomatoes, peppers, or any other summer vegetables. I sow endive, kale, lettuce, Chinese cabbage, and, if I could stomach it, cauliflower seeds in midsummer in seed flats. Once they sprout I “prick them out” into individual cells of automatic watering GrowEase trays for later transplanting. Autumn seedlingsNot only vegetables get this treatment. Buy a packet of seeds of delphinium, pinks, or some other perennial, sow them now, overwinter them in a cool place with good light, or a cold (but not too cold) place with very little light, and the result is enough plants for a sweeping field of blue or pink next year. Sown in the spring, they won’t bloom until their second season even though they’ll need lots of space that whole first season.

Cuttings are another way to propagate plants this time of year. Early this morning, when cells were plump with water, I made cuttings of hardy kiwifruit and begonia.

And, Yes, Weeds

Weeds can make all this pruning, watering, and seeding for naught. Clear ground is needed in which to eventually set my cabbage and kale transplants. Weeds stealing water and nutrients, even sunlight, won’t let plants grow at their best. They’ll also promote disease by preventing free flow of air; fungi fester under damp conditions. Weedless corn & lettuce bedEvery time I look at a weed, I’m thinking how it’s either sending roots further afield underground or is flowering (or will flower) to scatter its seed. Much of gardening isn’t about the here and now, so I also weed now for less weeds next season. It’s worth it.

Watering — in the Rain?

Why Are Pots Thirsty?

With recent rains of more than 3 inches over the last couple of days, you’d think that the last thing on my mind would be having to water anything. But you’d be wrong. Plants in pots — and I have plenty of them, some ornamental and some tropical and subtropical fruits — don’t get the full benefit of all that water.

Potting soils are, and should be, more porous than any garden soil to maintain good aeration within the confines of a pot. About a one inch depth of water is needed if you’re going to thoroughly wet a 12 inch high column of potting soil. If a flower pot is, for example, only 6 inches high, only 1/2 inch depth of water would be needed; and so on.

A lot of my potted plants didn’t drink in that 3 inches of rain that fell over the past couple of days. Some of the plants are shielded from the sky by overhanging house eaves. And the leaves of other plants — excepting amaryllis and calla lily which have strappy, upright leaves — deflect water that could have fallen into the pot.

If you don’t believe me, tip a potted plant out of its pot following a heavy rain, and check how dry the soil is down deep within the pot. Even easier, purchase an inexpensive moisture meter whose metal probe, when slid into the soil, reports moisture deep down.

(Sort of) High Tech Solution

When I first started gardening, I knew I would eventually move from the cottage I was renting. My mini-orchard was in pots and travel-ready. I kept that “orchard” watered by hand, which wasn’t so bad. The problem was that in the heat of summer, some plants needed their thirst quenched twice a day, which kept me from leaving my home for more than a few hours.

These days, technology has come to the rescue.

The first techno-solution has been drip irrigation. A simple, battery-operated timer at a spigot sends out water on a twice daily schedule to banks of potted plants. Also at the spigot, following the water line right after the timer, are a filter and a pressure reducer. automatic watering, potsThe fittings for wending water through tubes around corners and up into pots are low pressure fittings; the pressure lowers water pressure to a mere 20 psi.

Once the 1/2 inch main line makes its way to a group of potted plants, a 1/4 inch plastic line, plugged into the main line with, of course, a low pressure fitting, carries the water up to the ground surface of each pot.

If the water merely exited at this point, pots closer to the water source would be under higher pressure and so get more water than those more distant. And pots that were shorter or at lower elevation would likewise get more water. So I slid an emitter, that reliably puts out 1/2 gallon of water per hour, no matter what the incoming water pressure, on the end of each 1/4 inch line.

Capillarity to the Rescue

I have a number of lowbush blueberry, lingonberry, hollyhock, carnation, and blazing star plants growing in pots 4-inches and smaller. I’ll eventually plant them out in the garden. Until then, the plants need regular watering Snaking 1/4 inch tubes to all these pots would create a tangled nightmare.

Enter capillary mat watering. All these smaller pots sit on a mat of absorbent fabric spread over a tray held a couple of inches above a pan of water. Irrigation, capillary matPart of the capillary mat dips into the reservoir of water, which gets sucked up into the mat and then sucked up into the potting soil through the drainage holes in each flat-bottomed plant pot.

I periodically have to remember to add water to the reservoirs. Or, rather, “had to” because I ran a few of those drip tubes into the reservoirs, enough to keep them topped up with water to keep pace with plant use.

And a Presentation of Interest

I’ll be doing a presentation on August 18th on THE SCIENCE, ART, FUN, AND TASTY FRUIT OF ESPALIER in Copake Falls, NY. The presentation will explore the theory and the practice behind the pruning and orienting of branches to create an espalier. This decorative, usually 2-dimensional form, offers high yields of high quality fruit on a plant or plants that can be free-standing, decorating a wall or fence, or even creating the fence itself! I’ll go over which fruit plants work best and the branch pruning and orienting techniques that create and maintain espaliers that look good and yield especially delectable fruit. For more information, go to pear espalier flowering


Too Much or Too Little?

The current deficit of rainfall reminds me of the importance of watering — whether by hand, with a sprinkler, or drip, drip, drip via drip irrigation — in greening up a thumb.

Not that watering is definitely called for here in the “humid northeast;” historically, cultivated plants have gotten by mostly on natural rainfall. Historically, vegetable gardens also weren’t planted as intensely as they are these days. In one of my three-foot wide beds, for example, brussels sprouts plants at eighteen inches apart are flanked on one side by a row of fully grown turnips and on the other side by radishes. Five rows of onions run up and down another bed.

The rule of thumb I use for watering is that plants need the equivalent of one inch depth of water once a week.

Finger in soil to test for moisture

Finger in soil to test for moisture

This approximation doesn’t take into account the fact that my bed of sweet corn is thirstier than is my bed of onions, that my plants drew less water up from the soil during a recent calm, cloudy day than they will with today’s bright sunlight and breezes, and that warmer temperatures speed water loss. Still, an inch a week is a good approximation, one very workable around here where periodic rain allow some wiggle room in watering. Not so in parts of California and similar climates that remain reliably bone dry all summer.

A sprinkler, or a hand-held hose with a spray rose for small areas, and some randomly placed straight-sided cans to catch water are an easy way to tell how long to leave the spigot on to get that inch depth of water. Hand wateringUsually, about an hour, once a week, is what it takes. (That’s a long time to stand still holding a hose.) Unless it rains. Then less might be needed.

A rain gauge is an inexpensive way to know whether what seems like a soaking rain is really so. Or monitor soil moisture directly. Dig a hole, poke your finger into the soil, or, even better, purchase a “moisture meter” for less than $15; plunge the metal probe a few inches into the ground and read on the dial whether the ground down there is “dry,” “moist,” or “wet.” You want it moist.

Digital moisture probe.

Digital moisture probe.

Thirst Quenching a Drip at a Time

My vegetable plants get their thirst quenched with drip irrigation rather than a sprinkler. The idea of a drip system is to drip water into the soil at about the rate which plants are removing it. That doesn’t occur once a week, but every bright day, all day long.

That one inch per week rate translates to about three-quarters of a gallon per square foot. Dripline with beansMy drip system is on a timer, and the time needed to apply this amount depends on the rate of flow from each emitter as well as the spacing of emitters.

After a lot of calculations and approximations (many years ago), I determined that dripping for one-half hour per day would be about right. But, as I wrote, plants drink all day long, not just once a day. My drip timer can turn on and off at three specified times per day, so the plants get their thirst quenched three times spaced out during daylight hours at ten minutes per session. My old timer offered six sessions per day; then, plants got six waterings of 5 minutes each.Drip timer

Done. All I have to do is check every once in a while that all systems are go, which is one reason my drip lines run above ground. I can watch the dripping.

I do have to get out the watering can for the lettuce seedlings, the third planting of the season, that are soon to be set out, as well as for the recently planted row of carrot seeds and other recent seedings and transplants. Supplemental watering until roots of new plants stretch down into the region of the drip line’s wetting front, which spreads with the shape of an ice cream cone downward beneath each spot of dripping water.

(I’ll be leading a hands-on workshop on drip irrigation August 18th at the garden of Margaret Roach in Copake Falls. For more information, go to Margaret’s website, and type my name in the “search” box.)

Engineered Orifices

Note that I haven’t mentioned “soaker hoses.” Although the water oozes out from these porous hoses, they are not really “drip irrigation.” Sure, the water just oozes out slowly. But they’re inconsistent in output not only with water pressure and elevation, but also with time. And roots can grow inside buried soaker hoses, further muddying the water.

A real drip line has water emitters spaced six to twelve inches apart along their length, and those emitters aren’t mere holes punched in tubing. They are engineered orifices, designed to be relatively consistent in output with changes in incoming water pressure and changes in elevation along the line. They also are self-cleaning in case debris gets into the line.

And Now, A Word About Fireflies

Fun fact: Fireflies (which I knew as “lightning bugs” in my youth) are more than whimsy on a summer night; they’re also a gardener’s friend, feeding on, among other creatures, slugs.



Water In Air, In Soil, In Reserve

My houseplants enjoyed my absence more that I expected. I thought it might be harder on them. After all, with spring in the air (indoors) for a few weeks now, they were all pushing out new shoots from the ends and along stems that had lain dormant all winter. Citrus, avocado, and amaryllis were even flowering, and rosemary was getting ready to flower.

Lack of water was going to be the threat, 5 days of it, while I was far away wandering up and down streets and in and out of alleys of Havana, Cuba.Havana street scene

Through winter, I had eased my houseplant watering chores by using “water siphons” (aka “hydrospikes” or “self-watering probes”). These porous ceramic probes, filled with water and pushed into the potting soil, have the thin, flexible tubes coming out of their caps plunked into mason jars filled with water. I knew well just how thirsty the plants were, watching the water in the reservoirs into which the tubes that connect to the ceramic cones drop daily, in some cases a cup or more per day.Automatic watering spikes

Plants cool off by letting water evaporate through little holes in their leaves, called stomates. So leaving the house thermostat set to cooler temperature was going to help slow water loss.

Evaporation is faster, whether through stomates or from the potting soil, the drier the air. Heat from radiators is less drying than that from the wood stove, our usual source of heat — also helping plants that might be pining away in my absence.

I poured water into the saucers in which each pot sits. As this water evaporates it creates a microclimate around nearby plants, a microclimate slightly more humid than that of the rest of the house, cutting down water loss from the potting soil and through the leaves. The humid microclimate was made more so by cozying plants in a cluster right up next to each other. Pebbles in the saucers bumped up this benefit by increasing the evaporative surface area.

To further help plants through their period of neglect, I filled the saucers with more water than usual, with the water level a smidgen above the bottom of the pots. As the potting mix dried, it could suck this water into the pot by capillary action. I don’t usually let water sit in the saucers above the level of the bottom of any resident pot because then the bottom of the pot becomes waterlogged, eventually leading to dead roots. I figured a few days would do no harm, and surely less harm than would drying out of the whole plant.

My final ministration was to cut open a clear dry cleaner bag and drape it loosely over the clusters of plants to maintain even higher humidity.Houseplants covered to maintain high humidity

The upshot: The plants did not miss me even a little. They looked healthy and happy upon my return, perhaps even more so than with five days of constant attention!

Visitando El Jardín Botánico Nacional

One day in Cuba I ventured beyond Havana for a tour of the Jardín Botánico Nacional, or National Botanical Garden, which is adjacent to Parque Lenin (Vladimir, not John) Park. We bounced along on a tractor-pulled wagon through a landscape devoted to plants native to Cuba, then on into a savannah of plants of African origin, to groupings of plants indigenous to Latin America, and on through other tropical climates and ecosystems.

A few greenhouses there create special environments. One was a tropical rainforest greenhouse, with humidity kept high with frequent, automatic watering. A houseplant such as maranta formed an expansive groundcover there, and other familiar houseplants, such as peperomia, philodendron, begonia,, and spathiphyllum, either spread all over the ground or reached heights you would never see in a house.

A dry greenhouse, the covering, this time, to shed rainfall, was home to succulents and cactii. One cactus that caught my attention, especially so with Cuba’s connection to the Soviet Union, was the “Russian soldier cactus.” The upper portion of this upright cactus was furry and brown, just like a Russian soldier’s hat. (As far as cool, common names the Cubans have for plants, another one was “tourist tree,” so-named for its red, peeling bark, just like the skin of pale tourists that get too much tropical sun.)Russian soldier cactus

Another Orchid!?

I’m very happy with my two orchid plants — Dendrobium kingianum, the pink rock orchid, and Odontoglossum pulchellum, lily-of-the-valley orchid. Both bloom reliably once a year, in winter, for over a month. 

But one of the orchids at the Jardín Botánico Nacional caught my attention for more than its beauty. Spathoglotis plicata, sometimes called Phillipine ground orchid, blossoms all year ‘round. It’s a terrestrial orchid that’s also easy to grow, not needing an excess of light. I’m going to get one to add to my collection.Spathoglottis orchid

Orchids can become an obsession; I hope I’m not about to fall down a rabbit hole.


It Mite be a Pest

    Mites! Eek! A new pest in town (for me). Actually, the mites, which showed up on some newly rooted Meyer lemon cuttings, don’t really scare me, nothing like the scale insects that regularly turn up on some of my citrus. Chigger mites, scabies mites, dust mites, itch mites — they’re not pests of plants, and they WOULD scare me.
    The cuttings were well rooted and just sitting still, basking in a south-facing window, waiting for longer days and warmer temperatures before they can come alive. (They pick up an attenuated version of seasonal temperature changes at that window.) A few weeks ago I noticed a yellow stippling developing on the green leaves.Mite damage symptoms
    No panic; the plan was to wait a few weeks and see if the stippling disappears or if new growth, unstippled, develops. Citrus sometimes develop iron deficiency, which also yellows leaves, in cold soils, not because the soil lacks sufficient iron but because the roots aren’t at the top of their game in cold soil.
    A closer look a few days ago revealed, to the naked eye, very small black specks on the leaves. An even closer look, with a hand-held lens, revealed tiny mites crawling around on the leaves.
    Mites are mostly problems in dry, dusty conditions, not atypical for a house heated in winter and the usual for summer in Mediterranean climates such as California. One simple cure is to make conditions less dry and dusty. Climate change within the whole house would be impractical. Instead, I started giving the plants a daily spritzing with water.

Mites, photo with iPhone + hand lens!

Mites, photo with iPhone + hand lens!

   More potent sprays may be needed; fortunately they need not be toxic to humans. “Horticultural oil” sprays are effective as are sprays of insecticidal soap. Problem is that these sprays are inconvenient to use indoors, where excess spray would end up on windows, furniture, and floors. Sprays need to be repeated weekly to kill mites that hatched from eggs (which are spray resistant) since the last spray.
    Because the Meyer lemon cuttings are still small with very few leaves, I chose to go at them mano a mano, merely rubbing my fingers across each leaf to crush the buggers (technically arachnoids, like spiders, not bugs). As with the oil or soap sprays, mano a mano combat must be repeated to crush newly hatched mites. But it’s quick and satisfying.
    Mites do have many natural predators, among them other kinds of mites. Just like Jonathon Swift’s flea that “Hath smaller fleas that on him prey; And these have smaller still to bite ‘em; And so proceed ad infinitum.”

Low-Tech Auto Water

    Every couple of days I have to think of all the plants in the house (they’re not all “houseplants”) that need water, including the mite-infested Meyer lemon cuttings. Two devices or setups keep me sane and my plants healthy in the face of all this watering.



    Larger, potted plants — those in pots over about 4 inches in diameter — are serviced by “water siphons” (aka “hydrospikes”, “self-watering probes”). A porous ceramic probe, previously soaked in water, filled with water, then capped, is pushed into the potting soil. The far end of the long, thin, flexible tube that comes out of the cap is plunked into a reservoir of water. I use mason jars as reservoirs and pre-fill the tube with water so that the water column is continuous from the ceramic probe to the reservoir.
    Voila! As the potting soil dries out, it sucks water from the ceramic probe which sucks water along the tube from the reservoir. Larger pots need more than one ceramic probe.
   Capillary mat For smaller pots, I use capillary mats, which are nothing more than water-absorbing mats (available from on which sit the pots. The mat is laid on a stand that sits above a similarly shaped, one-inch-deep tray, with one end of the mat dipping down into the tray. The mat absorbs water from the reservoir and the potting soil in the pots, as they dry, absorb water from the mat.
    It’s important to maintain good capillary contact between the potting soil and the mat. This means no coarse drainage material in the bottom of the pots (a silly, counterproductive idea anyway), and no “feet” elevating the bottom of the pot.
    Not having to frequently water makes it all too easy to forget about watering. I already lost one old rosemary plant this winter. Hydrospikes and capillary mats don’t work — duh! — unless their reservoirs have water in them.