Go Drip!

This summer has been one of the hottest and driest ever — and it’s been one of the best ever in the vegetable garden. Baskets of red, ripe tomatoes and peppers sit on the kitchen floor awaiting metamorphosis into sauces and salsas, dehydration, or just plain being eaten.Dog Sammy and garden beds

What about water? My garden plants are plump with water thanks to drip irrigation. In addition to benefits to the plant, drip is also good for the environment, typically using only about 40 percent of the amount of water used by sprinkling. That’s because the more pinpointed water avoids wasting water in paths and other places it’s not needed. Also because little water is lost to evaporation.Dripline with beans

The “drip” in drip irrigation tells you that water is applied at a very slow rate, which is especially appealing to those of us whose water comes from a well. With drip, the well has plenty of time to recharge between waterings.

Drip is also better for plants. Leaves stay dry, lessening the chance for disease. And rather than flooding the ground, which a sprinkler does at each watering, drip keep soil moisture within that happy window when larger pores remain filled with air, and water is held within smaller pores so that roots can both breathe and draw in water. (This is one reason for the more efficient water use of drip irrigation.)

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Many Benefits of Drip

I’m a big fan of drip irrigation, an irrigation system by which water is frequently, but slowly, applied to the soil. It’s better for plants because soil moisture is replenished closer to the rate at which they drink it up. With a sprinkler, soil moisture levels vacillate between feast and famine.

Because of the efficient use of water, drip is also better for the environment, typically using 60 percent less water than sprinkling.
Dripline with beans
And drip is better for me — and you, if your garden or farmden is dripped. By pinpointing water to garden plants, large spaces between plants stay dry so there’s less weeds for us to pull. And best of all, with an inexpensive timer at the hose spigot, I turn on the system in April and then pretty much forget about watering until the end of the growing season.


Today I was reminded about the “pretty much” part of being able to forget about watering until the end of the season. My drip system is set up so that same main line that quenches plant thirst in my two vegetable gardens continues on to water about twenty potted plants. Or not!
Drip tubes to potted plants
I noticed yesterday that some of the potted plants were dry and assumed that the emitters bringing water to these pots were defective. Turns out that sometimes they dripped and sometimes they didn’t. Hmmm. I kept switching around and replacing the “defective” emitters and by the end of the day, for some reason, they were all working. Problem solved.

No! I have a hose connected near my well pump so that I can occasionally hand water some melons I’ve planted in a truckload of leaves a local landscaper provided me with last autumn. Water pressure was very low. 

Long story short is that the seasonal line from the well to the pump has a short section of flexible, almost clear plastic tubing. Sun shining on the tubing grew a nice crop of algae within. I disconnected the tube and was able to remove an almost intact tube of algae that had been clogging the line. That was the culprit responsible for the capricious behavior of the drip system and the sluggish behavior of the hose for hand watering.

Thorough cleaning and reconnecting the tubing, wrapping it in aluminum foil to exclude light, priming the pump, and cleaning the sediment filter in the drip line had everything working waterly again. Geez, you gotta be a rocket science to keep things working smoothly. Well, not quite.

I’ve now marked my calendar to check the drip system every 3 weeks.

Some Attention Necessary

In addition to checking periodically to make sure that the water flows unobstructed, my watering system — any drip system —  requires other regular attention, including a small amount of hand watering. The reason has to do with the shape of the wetting front drip presents in the soil. As a drip of water enters the ground, gravity pulls water downward at the same time that capillary action is pulling the water horizontally.  Down in the ground, that wetting front is shaped like an ice cream cone, at first widening with depth and then narrowing to a point.

The width of the cone depends on soil porosity. Clay soils have small particles with commensurately small pores (illustration from my book Weedless Gardening).
Wetting front various soil types
Those small pores exert a strong capillary pull so the ice cream cone spreads wide, as much a six feet at its widest down from each point source of water. At the other extreme is a sandy soil, whose large particles have large spaces between them and comparatively little capillary pull; the result is a slender ice cream cone, spreading no more that a couple of feet wide.

A drip system is a series of emitters, so the wetting fronts can merge together at their widest points presenting a wetting front that in soil cross section looks like waves below ground, with peaks at ground level at each emitter. (This illustration is also from Weedless Gardening.)
Wetting fronts, merging
Distance between peaks depends on the spacing of drip emitters. Depth of the wave troughs between the peaks depends on the soil texture and emitter spacing. A soil rich in clay with close emitter spacing would be wet at the peaks, with the “waves” relatively close to the ground surface between the peaks.

Between emitter peaks, the ground is dry near the surface. Plant a seed there and, in the absence of rain, the seed will just sit. Tuck a transplant into the soil there and, in the absence of rain, it will dry out and die. Hand watering gets that seed or transplant’s roots growing; once the roots reach down far enough to tap into the wetting front, they’re on their own.
Watering by hand
To avoid hand watering I sometimes move the drip line right over the row where I planted seeds or right along the row where I set transplants. After a few days or once seeds sprout, I move the drip line back to its rightful position which, along with one other line, is about 9 inches in from each of the outer edges of my 3 foot wide vegetable beds. 

Only one more maintenance item for my drip system. If it has rained cats and dogs, that is, more than 1 inch, as measured in a rain gauge, I might turn off the drip system temporarily. Then — and this is very important — I’ll stick a Post-It note  on which is written “Drip” to my bathroom mirror as a reminder to turn the drip system back on in due time. Drip irrigation is low maintenance, but not no maintenance.

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

For when the weather turns dry, this season, next season, and on.. .

Drip workshop ad, 2018

Also on that same date, at the same location, in the morning . . . a presentation on:


Come and explore the theory and the practice behind the pruning and orienting of branches to create an espalier. This decorative 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! Learn which fruit plants work best and the techniques to create and maintain an espalier.

Pear espalier



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.




With blossoms spent on forsythias, lilacs, fruit trees, and clove currants, spring’s flamboyant flower show had subsided – or so I thought. Pulling into my driveway, I was pleasantly startled by the profusion of orchid-like blossoms on the Chinese yellowhorn tree (Xanthoceras sorbifolium). And I again let out an audible “Wow” as I stepped onto my terrace, when three fat, red blossoms, each the size of a dinner plate, stared back at me from my tree peony.

Tree peony blossoms

Both plants originate in Asia. Both plants are easy to grow. Both plants have an unfortunate short bloom period, more or less depending on the weather. Fortunately, both plants also are attractive, though more sedately, even after their blossoms fade.

The tree peonies have such a weird growth habit. I had read that they were very slow to grow so was quite pleased, years ago, when each of the branches on my new plant extended its reach more than a foot by the end of its first growing season. Tree peony is a small shrub; at that rate mine would be full size within a very few years. Or so I imagined.

The tree peony still grows that much every year. But every year many stems also die back about a foot, more following cold winters. No matter, though, because every May giant silky, red flowers unfold from the remaining fat buds along the stem.Yellowhorn blossoms

I originally planted Chinese yellowhorn not for its flowers but for the fruits that follow the flowers. Each fruit is a dry capsule that later in summer starts to split open to reveal within a clutch of shiny, brown, macadamia-sized nuts. Yellowhorn frequently makes it onto permaculture plant lists, with the edible nuts billed as having macadamia-like flavor also. Not true. I’ve tried them raw and roasted. Roasting does change the flavor, but raw or roasted, the flavor is bad.Yellowhorn tree

Still, those blossoms make yellowhorn well worth growing. And after the blossoms fade, this small tree is adorned with shiny, lacy leaves. Much like the tree peony, yellowhorn grows many new stems each year, and many of the stems die back, not necessarily from winter cold but because they’re seemingly deciduous. I tidied the tree up last week by pruning off all the dead stems.

Out With You-All

Today, May 25th, with temperatures around 90 degrees F., I may not be able to restrain myself. It’s hard to imagine that temperatures could still plummet below freezing at least one night sometime in the next week or so. I’ve already ignored that “should” and a few days ago moved houseplants outdoors.

Why the rush? First of all, houseplants enjoy growing outdoors more than growing indoors. Outside, breezes rustling leaves and stems make for stronger, stockier growth and rain showering the leaves washes off a winter’s accumulation of dirt and grime.

After a winter indoors, the plants do need to acclimate to these conditions, which is why they start their outdoor vacation on the terrace on the north side of the house, which blocks wind and, for part of the day, sunlight.

I also urged the plants outdoors because populations of aphid and scale insects were outgrowing the appetites of the ladybugs crawling up and down the stems. Outside, natural predators keep pests in check and, if necessary, I can spritz the plants down to knock off pests and spray soap or summer oil to kill them without worrying about getting spray or oil on windows, walls, or furniture.

The Rush On Sweet CornCorn planting

Even tender seeds, such as corn, squash , and beans, can be sown now. The earth has warmed enough for decent germination, and by the time the plants are up, warm weather will have settled in for the season.

Tomorrow I plant sweet corn. Kinky as it sounds, I’m anxious to sink my teeth into a freshly picked ear.

Upcoming Workshop

June 24, 1-4:30 pm, DRIP IRRIGATION WORKSHOP at the garden of Margaret Roach in Copake Falls, NY. Don’t wait for dry weather to learn about this easy and better (for you and plants) way to water, including participation in hands-on installation. For more information and registration,


 I’m Dripping, So Why Am I Watering?

  Up to a couple of weeks ago, little water had dropped from the sky this spring here in the Hudson Valley. But a drip irrigation system automatically waters many of my plants. So why have I been spending so much time with hose in hand?Dripline with beans
    Not all my plants drink in the drips. Trees and shrubs are on their own except their first year in the ground when I religiously hand water them every few days initially, and then once a week throughout the season. These plants get 3/4 gallon per week for every square foot spread (estimated) of their root systems. That’s equivalent to an inch of rainfall which, if it does fall, exempts me from a few days of watering.
    A couple of inches depth of hay, leaf, or wood chip mulch around the trees and shrubs seals in moisture to make best use of my efforts. Also, I start with smaller plants — less than 4 feet tall — which become independent of my watering sooner because a larger proportion of their roots are soon foraging around in surrounding soil that those of larger plants.
    My flower beds also don’t get dripped. Although the soil surface is dry, moisture carried over from winter still sits in lower depths, into which established perennial flowers’ roots can tap. Annuals and newly planted perennials need to be watered on the same schedule as young trees until their roots reach that moisture.

My blueberries are my only dripped shrubs

My blueberries are my only dripped shrubs

   It is my garden vegetables that drink in the benefits of my drip system. But even here some hand watering is needed these days. Down each bed runs 1 or 2 drip lines, with emitters along the lines spaced 6 inches apart. As water enters the soil, capillary pull from small spaces between the soil particles draws water sideways and, along with gravity, downward. The resulting wetting fronts have the shape, if you could look at a cross-section of the soil, of an ice cream cone. In clay soils, with small particles and, hence, a lot of capillary draw, that ice cream cone is very fat; in sandy soils, it’s narrow, a couple of feet wide at its broadest as compared with the 6 foot spread in a clay soil.
    The wetting fronts start their sideways spread below the soil surface, deeper in sandy soils, more shallow in clay soils. In either case, the soil surface remains dry except right at the point of drip. So any vegetable transplants or seeds I set in the ground need to be hand watered until their roots reach the wetting front — except for seeds or transplants set right under or along the drip line.

Drip Irrigation Workshop June 20th; see “Workshops“, at this site, for more information.

A Statue of David

    My friend David was wondering why the leaves of his Romaine lettuce plants flopped down. I gave my usual response to most gardening questions: “Too little water.” (My other usual response is “Too much water,” often following my first response if the questioner tells of watering all the time.)
    So I asked David how much he watered, and he said he thoroughly soaked the ground by spraying it with water. Busted! It really was a water problem, too little in this case.Hand watering
    In fact, thoroughly wetting the soil with the usual 4-foot-diameter, hand held spray is almost impossible. “Thoroughly wet” means soaking the ground to at least a 6-inch depth. For his hand held sprayer to do that, David would have to stand in place like a statue, sprayer in hand, unmoving, for about an hour to wet one 4-foot-diameter part of the garden before moving on to the next 4-foot-diameter area.
    When I’m watering plants in the ground by hand, I’m wetting only the small area beneath an individual plant, just enough to soak its roots as they establish themselves in the surrounding soil.

Probe the Soil

    People find it hard to believe that that statuesque watering posture is really necessary. All you have to do is scratch the soil surface after a David-esque spraying of plants to see how deeply the water percolated, and you’d find only a thin layer of wet soil, at the surface.

Digital moisture probe.

Digital moisture probe.

   Digging a hole in the ground is a good way to tell if watering was sufficient. But it’s also inconvenient.
    For just a few dollars, I invested, years ago, in an electronic gizmo that bypasses all that hole digging. This soil moisture sensor has a metal probe that you plunge into the soil. Atop the probe is a dial or digital readout that tells whether the soil is “DRY,” “WET,” or something in between. More accurate sensors cost over a hundred dollars, but the cheap ones are fairly accurate and work well if coupled with observation.

Good for Pot(s) Also

    The soil moisture meter is especially useful with potted plants, which might need watering every day when the weather is warm, sunny, and breezy. (With experience, lifting a pot to feel its weight is also a good measure of moisture level, as is just getting to know your plants better.)
    I’m still hand watering the pots because I haven’t yet connected the drip tubes that will direct water to each of the pots.