Water deeply and mulch
The one-inch convention in gallons, the finger test, hose timing, drip run times, containers, rain barrels, and mulch materials and depths.
Start here Essentials
This module asks for a watering routine you can write down: when to water, how much, and a mulch that cuts how much you need. Everything marked Go deeper is optional on a first pass.
- Check the soil 2 inches down before you water. Dry: water. Moist: wait a day or two. Wet or muddy: do not water. The two-inch check.
- Water in the morning, at the base of the plants, slowly. If a plant wilts and the soil is dry, water at once. Morning, at the soil, slowly.
- Size the week. Gallons for one inch = area in square feet x 0.623. Time your hose with a 5-gallon pail, or use the water calculator. For pots, water at least daily in hot weather until water drains from the bottom. One inch a week, in gallons.
- Mulch once the soil has warmed and plants are established: 2 to 4 inches of seed-free straw or shredded leaves, or about 3 inches of compost, an inch or two back from each stem. Mulch.
- Write your routine down: how you check, how many gallons or minutes, and which days.
Minimum time: about 30 minutes, then a few minutes at each watering. Done when: a watering routine is written down.
1. One inch a week, in gallons Understand
Water is the garden task that rarely pauses. From the first sowing to the last harvest, a vegetable bed loses water every day to evaporation from the soil and to the plants themselves, which draw water up through their roots and release it through their leaves. A week without rain in July can stop a tomato setting fruit. A week of daily sprinkling can leave the top inch wet and the roots dry. This module turns watering from a guess into a measured amount, and then reduces how much you need with mulch.
The one-inch convention
University of Minnesota Extension's watering guide says a vegetable garden needs about one inch of water a week, from rain or irrigation. Convention That figure is a starting point, not a measurement of your garden. Other extension services publish ranges: Penn State Extension gives 1 to 1.5 inches a week for vegetable crops, with the lower end for small plants and the upper end for large ones, and says hot or windy weather may call for more than 1.5. The University of Arkansas's drip irrigation fact sheet (FSA6174) gives about 1 to 2 inches, and notes that a mature fruiting tomato may need close to 2 while new transplants may need less than 1.
| Source | Inches per week | Notes |
|---|---|---|
| University of Minnesota Extension | About 1 | Sandy soil: half an inch twice a week |
| Penn State Extension | 1 to 1.5 | Low end for small plants, high end for large; more in hot or windy weather. Written for farm-scale drip. |
| University of Arkansas (FSA6174) | About 1 to 2 | Seedlings less than 1; a mature fruiting tomato close to 2 |
The sources agree that one inch is the floor for an established garden in ordinary weather, and that the right amount rises with plant size, heat, wind and fast-draining soil. The course's water calculator defaults to one inch and lets you change it. The two-inch check in the next section is what tells you whether your number is right.
Why inches, and how to turn them into gallons
Rain is measured in inches of depth, so watering is too: an inch of irrigation is the amount that would cover the bed one inch deep if none soaked in. Depth is useful because it does not depend on the size of the garden. Gallons are useful because a hose, a can and a barrel are measured in them. The conversion is fixed geometry.
Physical principle One square foot covered one inch deep is 12 in x 12 in x 1 in = 144 cubic inches. A US gallon is 231 cubic inches, per the National Institute of Standards and Technology's Handbook 44. So one inch on one square foot is 144 / 231 = 0.623 gallons.
The same figure comes out of two other published numbers. The University of Arizona's Water Wise sheet on rainwater catchment gives its collection formula as area in square feet x inches of rain x 0.623. The U.S. Geological Survey's Water Science School says a one-inch rain deposits 27,154 gallons on an acre; an acre is 43,560 square feet, and 27,154 / 43,560 = 0.623.
- Gallons for one inch = area in square feet x 0.623.
- Gallons for a week = area x (target inches - rain inches) x 0.623, and never less than zero.
Minnesota's guide rounds this to 62 gallons for 100 square feet, and gives a 600 square-foot garden about 372 gallons after a week with no rain. A 4 x 8 ft raised bed is 32 square feet, so one inch is 32 x 0.623 = 19.9 gallons. Those numbers surprise most people. A two-gallon watering can covers about three square feet with an inch of water.
Measure rain with a straight-sided rain gauge in the open near the garden, read it after each rain, and subtract the week's total. Penn State's guidance adds an exception: under plastic mulch, rain does not reach the soil, so the whole weekly amount comes from irrigation regardless of rainfall.
Soil texture changes the schedule, not the total
Physical principle Sand holds little water and drains fast; clay holds more and drains slowly. Module 3 covered how to estimate your soil's texture. The University of Arkansas fact sheet tabulates the difference: a sandy loam holds about 0.10 to 0.12 inches of water per inch of soil, a loam 0.13 to 0.17, and coarse sand as little as 0.02 to 0.06.
Minnesota's guide turns that into a schedule. On sandy, well-drained soil, water twice a week, about half an inch (31 gallons per 100 square feet) each time. On heavier clay or loam rich in organic matter, once a week is fine. Convention The weekly total is the same; sandy soil needs it split because it cannot hold a whole inch in the root zone at once, and the excess drains below the roots.
Clay has the opposite limit. Water soaks into clay slowly, so a hose run fast on clay floods the surface and runs off before it soaks in. The fix is to apply water slowly, or in two sessions an hour apart, not to apply less.
Containers and raised beds dry faster
A container has a small volume of mix and no soil below it to draw on. Penn State Extension's container guide says to water containers at least once a day in hot summer months, and to water until water drains from the holes in the bottom, which shows the whole root zone is wet. The one-inch convention does not translate into containers, because the plant's water comes from the volume of mix, not the surface area. For a pot, the measure is the drainage and a finger in the mix.
Raised beds sit between the two. University of Maryland Extension notes that raised beds dry faster and need more monitoring and irrigation in hot, dry weather, and that beds built on a hard surface dry out more quickly still, because roots cannot reach the moisture in the ground below. Check raised beds before in-ground beds on a hot day.
One inch a week is a starting convention for established plants in typical soil. Seedlings, sandy soil, containers, raised beds on pavement, heat and wind change it, and the extension sources above disagree on the upper end. The gallons this module computes are the amount to apply; whether that amount is enough is decided by the soil two inches down, checked every time. The calculator cannot see your weather or your soil.
When to water: the two-inch check
The number tells you how much. The soil tells you when. Minnesota's guide gives the check: pull back any mulch, dig into the soil with a trowel, and look. Test it The top inch may be dry, but the soil below should be somewhat moist; if it is dry two inches below the surface, it is time to water. A finger pushed in to the second knuckle does the same job in loose soil. We call this the two-inch check.
The root zone is the volume of soil that a plant's roots occupy and draw water from; the University of Arkansas tables assume a vegetable root zone 10 inches deep. The two-inch check samples the top of the root zone, which dries first. It tells you to water before the roots further down run short.
Three readings, three actions:
- Dry at two inches: water the planned amount.
- Moist at two inches: wait, and check again in a day or two, sooner in heat.
- Wet or muddy at two inches: do not water; roots need air as well as water. If it stays wet for days, the soil is draining poorly, which is a soil question for Module 3 and a bed question for Module 4.
Record the reading as dry, moist or wet in the weekly water sheet, with the rain and the gallons you gave. After a few weeks you will see how many days your soil goes between waterings in cool weather and in hot, which is the schedule the convention cannot give you.
Morning, at the soil, slowly
Minnesota's guide recommends watering early in the day, and gives the reason: plant roots need the water, not the leaves, and wet leaves, especially overnight, encourage leaf diseases. Convention Put the water at the base of the plants and apply it slowly so it soaks in. A morning watering lets any wet leaves dry in the sun, and less water evaporates in the cool of the morning than in midday heat.
The same guide makes one exception that matters: do not wait for morning when plants are wilting from drought. A plant that is wilted and has dry soil at two inches needs water now, in the afternoon or evening if that is when you find it. Test it Afternoon drooping with moist soil is different: large leaves can lose water faster than roots supply it in strong heat, even from moist soil. If the plant recovers by evening, it was heat, not a dry root zone. Check the soil before deciding which you are seeing.
How to water: hose, drip and the run-time formula
Timing a hose with a five-gallon pail
A hose has no gallon meter, but you can calibrate it once. Minnesota's guide describes the method: use a bucket of known volume, such as a five-gallon pail marked at the five-gallon line, and time how long your hose takes to fill it at the setting you normally use. Repeat it to confirm. Because 62 gallons is about 12 pails, it then takes 12 times that fill time to put an inch on 100 square feet.
The general form, which the water calculator uses:
- Minutes of hose time = gallons needed / 5 x seconds to fill the pail / 60.
Worked through for one 4 x 8 ft bed and a hose that fills the pail in 60 seconds: 32 x 0.623 = 19.9 gallons; 19.9 / 5 = 3.99 pails; 3.99 x 60 seconds = 239 seconds, or just under 4 minutes. Hold the hose at the base of the plants, move along the bed, and stop at the time. Most people who time this find they had been watering for a fraction of what an inch takes.
The fill time changes if you change the nozzle, the tap setting or the hose length, or if a neighbor on a shared line is running water at the same time. Time it again after any change.
Drip and soaker lines Go deeper
Drip irrigation delivers water slowly to the soil at the base of plants through tubing fitted with emitters. An emitter is a fitting that releases water at a fixed rate, rated in gallons per hour (gph). A soaker hose is a porous hose that seeps water along its whole length rather than at fixed points. Both put water where the two-inch check looks for it, keep leaves dry and lose little to evaporation. Both take setup and checking.
Clemson University's Home and Garden Information Center describes the standard parts. Product-specific Common emitter rates are half a gallon, one gallon and two gallons per hour. Drip systems work well at 20 to 30 psi, and pressures above 40 psi can burst tubing or push emitters out, so a pressure regulator, a fitting that lowers and steadies the water pressure from the tap, is part of every system. A filter is required too, because emitter openings are tiny and clog. The University of Arizona's sheet gives 15 to 20 psi for drip and soaker hoses. The two figures differ; the rating printed on your regulator and tubing is the one that applies to your system.
The run-time formula
The question with drip is how long to run it. The University of Arkansas fact sheet FSA6174 gives the formula for the application rate, the depth of water a system delivers per hour over the area it serves:
- Drip rate (inches per hour) = emitter flow (gph) x 231.1 / (emitter spacing in inches x bed width in inches).
- Run time (hours) = target inches / drip rate.
Physical principle The formula is the gallon conversion again. Each emitter delivers its gallons per hour; times about 231 cubic inches per gallon gives cubic inches per hour; dividing by the rectangle of soil each emitter serves (its spacing along the line times the width the line waters) gives inches of depth per hour. For a bed with one drip line, the width is the bed width. For a bed with several lines, Arkansas says to use the distance between lines.
Arkansas's own example: emitters of 0.3 gph spaced 12 inches apart on a 24-inch bed. 0.3 x 231.1 = 69.3; 12 x 24 = 288; 69.3 / 288 = 0.24 inches per hour. One inch takes 1 / 0.24 = about 4.2 hours, which the fact sheet gives as 250 minutes a week.
A home example: a 4-ft bed with two drip lines 24 inches apart and 0.5 gph emitters every 12 inches. 0.5 x 231.1 / (12 x 24) = 115.6 / 288 = 0.40 inches per hour. One inch takes 2.5 hours, or 150 minutes a week. The drip calculator does this arithmetic from your own figures.
Arkansas adds a second limit that matters as much as the total. Each soil can absorb only so much at once, and the fact sheet tabulates a maximum run time for a single watering by soil and flow rate. In its sandy loam example, the weekly 250 minutes should be split into sessions of no more than 41 to 49 minutes, run 5 or 6 times a week, so water does not run off or drain below the roots. Convention If your line's flow falls outside that table, split the weekly total into several runs anyway and use the two-inch check to see whether each run is wetting the root zone without puddling.
The tablespoon test
The label rate of an emitter is what it delivers at its rated pressure, new and clean. A clogged emitter or a long run with low pressure delivers less. The UC Master Gardeners of Solano and Yolo counties publish a quick check: time how many seconds an emitter takes to fill a tablespoon. Their figures: a 1 gph emitter takes 14 seconds, a 2 gph emitter 7 seconds.
Test it The arithmetic behind it: a gallon is 128 fluid ounces and a tablespoon is half an ounce, so a gallon is 256 tablespoons. At 1 gph, 256 tablespoons an hour is one every 3,600 / 256 = 14 seconds. A 0.5 gph emitter should take about 28 seconds. Test emitters near the start and the far end of a line; if the far ones are much slower, the line is too long for the pressure, or something is clogged. Use the measured rate, not the label rate, in the run-time formula.
The same handout advises running drip long enough to wet the soil 12 to 18 inches deep and watering less often. That is one master gardener program's guidance, written for drip across a home landscape; for vegetables, the two-inch check and a trowel pushed deeper after a run tell you how far the water went.
Rain barrels
A rain barrel collects runoff from a roof downspout. It is a modest supply, and the arithmetic shows how modest. A typical 55-gallon barrel holds 55 / 0.623 = 88 square-foot-inches of water: one inch on 88 square feet, which covers a pair of 4 x 8 ft beds (64 square feet) with a little to spare. The University of Arizona's sheet gives 623 gallons per inch of rain on 1,000 square feet of roof, so about 88 square feet of roof fills that barrel in a one-inch rain. Most barrels overflow early in a storm and run dry within a week of heavy use.
What to know before using barrel water on vegetables
Rutgers Cooperative Extension's fact sheet FS1218, on testing harvested rainwater for vegetable gardens, is a useful example of what the questions are. We use it as a labelled New Jersey example; your own state's guidance may differ.
- First flush. The first flush is the first runoff from a roof in a rain, which carries most of the dust, droppings and debris that settled on it. Rutgers notes that cisterns usually have a first-flush diverter that sends this water away, and that rain barrels often do not.
- Soil, not leaves. Rutgers says harvested rainwater should be applied only to the soil, possibly by drip, and kept off the plant itself; a watering can is fine if the water does not land on the plant.
- Morning, and not right before harvest. Rutgers says to apply it in the morning only, and not to harvest right after watering, so leaves dry and sunlight can act on them first.
- Not drinking water. Rutgers states that in New Jersey harvested rainwater cannot normally be used as drinking water under the Safe Drinking Water Act. In its sampling of barrels fed by asphalt-shingle roofs, E. coli exceeded irrigation standards in 9 percent of samples and drinking water standards in 66 percent.
- Mosquitoes and algae. The University of Arizona's sheet says to screen every opening of the container against mosquitoes and to use an opaque container so algae do not grow.
Whether you may collect rainwater at all, how much, and whether it may touch edible crops can depend on state law, a city ordinance, a plumbing code or an HOA. Rutgers' guidance above describes New Jersey and one study's roofs. Ask the authority Ask your state or local extension office and your city or water utility before installing a barrel, and your HOA or landlord in writing if you have one. Do not use barrel water for drinking, washing produce or anything that needs safe water.
Mulch: materials, depths and timing
Mulch is a layer of material spread over the soil surface around plants. For a vegetable garden, it does several jobs at once. The University of Georgia's circular on mulching vegetables (C984) lists them: mulch reduces moisture loss from the soil, suppresses weeds, reduces fertilizer leaching and cools the soil, and it helps prevent fruit rots by keeping fruit off bare ground and cutting down on mud splashed up by heavy rain. Minnesota's watering guide adds the result that matters most for this module: mulched soil holds water better, so you may water less often.
Physical principle Bare soil loses water from its surface to sun and wind. A loose layer of organic material shades the surface and traps a layer of still, humid air above it, slowing that loss. The same layer blocks light from weed seeds, most of which need light near the surface to germinate.
Materials and depths
Iowa State University Extension's mulch guide gives 2 to 4 inches as generally effective, with coarser materials at the deeper end and finer ones at the shallower end. Georgia's circular suggests 3 to 4 inches, and up to about 5 for very light material. Too thin a layer controls few weeds; too thick a layer can keep air from the roots. Georgia also gives shallower limits for several fine materials.
| Material | Depth | What the sources say |
|---|---|---|
| Straw | 2 to 4 in (Iowa State), 3 to 4 in (Georgia) | Iowa State calls it an excellent vegetable mulch and says to use straw free of seeds. Georgia notes straw and hay often carry weed seeds and do not last long. |
| Shredded leaves | 2 to 4 in | Iowa State: great for vegetable gardens. Georgia: whole leaves can form a soggy mat; shred them or mix them with fluffier material. |
| Grass clippings, dried | Within 2 to 4 in overall (Iowa State) | Iowa State: dry them first, because fresh clippings mat and smell; skip clippings from a lawn treated with a broadleaf herbicide until after two or three mowings, and from weedy lawns, which carry seed. |
| Compost | About 3 in (EPA) | EPA's home composting page: loosen the top 2 to 3 inches of soil, spread a 3-inch layer, and keep it a few inches from plant stems. Iowa State notes compost suppresses weeds less well than other mulches. |
| Newspaper or cardboard, under another mulch | 2 to 3 sheets of newspaper (up to 10), or 1 to 2 layers of cardboard | Iowa State: avoid glossy paper and waxed cardboard, remove tape and staples, cover with an organic mulch, and do not use so many layers that water and air cannot pass. Georgia: paper is high in carbon, and the circular calls for nitrogen fertilizer first. |
| Wood chips | Within 2 to 4 in overall (Iowa State) | Oregon State: large chips left on the surface tie up less nitrogen than chips mixed into soil; suits paths and the soil surface around plants. Georgia's circular calls for nitrogen first; see the note below the table. Iowa State: avoid chips made from lumber or pallets. |
| Sawdust | No more than 2 in (Georgia) | Oregon State: fine particles such as sawdust tie up more nitrogen than chips, and more again when mixed into soil. Georgia: add nitrogen fertilizer first. Iowa State: avoid sawdust from treated lumber. |
| Plastic film | One layer | Georgia: black or clear plastic warms soil and can bring earlier crops. Minnesota and Penn State: rain does not pass through it, so lay drip lines first and supply the full weekly amount by irrigation. |
The nitrogen cautions have one cause, and how much it matters depends on how you use the material. Physical principle Woody and paper materials are high in carbon and low in nitrogen. As soil microbes break them down, they take up nitrogen that plants would otherwise use. Oregon State Extension's page Wood chips for mulch? draws two distinctions. Small particles such as sawdust tie up more nitrogen than large chips, and chips mixed into the soil tie up more than chips left on the surface. It recommends chips as a mulch on paths and on the soil surface around plants, and warns against tilling fine chips into a garden. It does not tell gardeners to add nitrogen before a surface mulch of chips. Georgia's circular does, for wood chips, sawdust and paper. Convention So the two sources agree about the risk and differ about the remedy. Do not add fertilizer just because the table mentions nitrogen. If you dig woody material or sawdust into a bed, or use sawdust as a mulch, that is the case both sources warn about, and Module 9 covers nitrogen and the label math for any fertilizer you add. Straw, shredded leaves and compost are the common first-season choices because they avoid the question and break down into organic matter by the end of the season.
When to mulch
Iowa State warns that mulch put down too early in spring insulates the ground and slows its warming. Convention For warm-season crops such as tomato, pepper, squash and beans, wait to mulch until the soil has warmed and the plants are established; the soil temperatures in Module 6 are the guide. Around direct-sown crops, wait until seedlings are up and thinned, then mulch between them. Georgia notes that mulch cools the soil, which suits cool-season crops still growing as summer arrives.
Keep mulch off stems
EPA's home composting page says to keep a compost mulch a few inches away from plant stems. Iowa State gives the reason for woody plants: mulch piled against a trunk keeps it moist and invites rot. Convention We apply the same rule to vegetables: leave a ring of bare soil an inch or two wide around each stem, so the stem stays dry. Pull mulch back when you do the two-inch check, and replace it after.
2. See it See it
Two of the course's fictional cases. Frost dates, test results, hose times and every other figure in them are invented for the examples; they are not measurements of any real garden.
The Okafor garden: a week of water in gallons and minutes. The Okafors have two 4 x 8 ft raised beds, 64 square feet in all, filled with 2 parts screened topsoil to 1 part compost. Their spigot is 20 feet away. They timed their hose at the setting they use: 66 seconds to fill a five-gallon pail, twice, with the same result.
An inch on 64 square feet is 64 x 0.623 = 39.9 gallons. Their rain gauge read 0.3 inches this week, so 0.7 inches is still needed: 64 x 0.7 x 0.623 = 27.9 gallons. In hose time, 27.9 / 5 = 5.58 pails, x 66 seconds = 368 seconds, or 6 minutes 8 seconds. With no rain, the full inch would take 39.9 / 5 x 66 = 527 seconds, about 8 minutes 47 seconds.
They do the two-inch check before watering. On Thursday the east bed is dry at two inches and the west bed is moist. They water the east bed for half the time, 3 minutes 4 seconds, and recheck the west bed on Saturday. After the tomatoes are established in late May, they lay 3 inches of straw, keeping it an inch or two back from each stem.
- Known: area (64 sq ft); the hose's fill time (66 seconds, measured twice); this week's rain (0.3 in, from their gauge); the arithmetic.
- Assumed: that one inch a week suits their beds. Raised beds dry faster (Maryland), so the convention may be low in July; their assumption, tested weekly by the two-inch check.
- Open: whether the maple's afternoon shade on the east bed from July changes how fast it dries. Settled by their own weekly water sheet, which records the soil reading for each bed.
The Lindqvist garden: what a rain barrel covers. Nils and Karin Lindqvist garden 600 square feet in ground and have a 55-gallon rain barrel and a hose. One inch on 600 square feet is 600 x 0.623 = 373.8 gallons; Minnesota's rounder figure gives about 372. Their barrel is 55 / 373.8 = 0.15 inches over the whole garden, or one inch on about 88 square feet.
They decide the barrel waters the winter squash hills and the hose does the rest. They fit a screen over the barrel's openings against mosquitoes, apply the water with a can at the soil only, in the morning, and do not harvest from the hills on a day they water them. Those practices come from Rutgers' New Jersey guidance and the University of Arizona's sheet; their own state's rules are a separate question.
- Known: barrel volume; garden area; the gallons-per-inch arithmetic.
- Assumed: that Rutgers' New Jersey practices (soil only, morning, no harvest right after watering) are a reasonable standard where they live; their assumption, labelled as such.
- Open: whether their state or town has rules on rain barrels or on using the water on food crops. Settled by their state extension office and town; they asked the extension office by email.
- Open: how much the barrel refills in a typical week. Settled by their own records: they note the barrel level in the weekly water sheet's notes.
Free references and demonstrations:
- Watering the vegetable garden (University of Minnesota Extension): the one-inch convention, 62 gallons per 100 square feet, the two-inch check and the pail method.
- Drip Irrigation Fundamentals: The Math Behind the Drip (University of Arkansas FSA6174): the run-time formula, soil water-holding tables and a maximum run time per session.
- Rain Barrels Part IV (Rutgers Cooperative Extension FS1218): test results from New Jersey rain barrels and how to apply the water to vegetables.
- Mulching Vegetables (University of Georgia Circular 984): what mulch does, and depths and cautions material by material.
3. Practice Practice
Minimum: Measure the area, compute the gallons, time the hose, do the two-inch check and choose a mulch; skip drip testing, the rain gauge and the water sheet. Time: about 45 minutes the first time, then 10 minutes a week. Materials: a five-gallon pail with the five-gallon line marked, a watch or phone timer, a tape measure, a trowel, a rain gauge or a straight-sided can, and, if you use drip, a tablespoon.
- Measure the area. Measure each bed's length and width in feet and multiply. Add the beds. For containers, count them and note their sizes instead.
- Compute the weekly gallons. Area x 0.623 gives gallons for one inch. Enter it in the water calculator, which also subtracts rain.
- Time the hose. Fill the pail at your usual setting and time it. Do it twice. Enter the seconds in the calculator and write down the minutes it gives for a full inch.
- Go deeper If you use drip, test it. Time three emitters, near the start, middle and end of the line, filling a tablespoon. Compute each one's rate, then use the measured rate, the spacing and the width in the drip calculator for a run time.
- Do the two-inch check. Dig in each bed with the trowel. Write dry, moist or wet for each.
- Go deeper Set up the gauge. Put a rain gauge in the open near the beds and read it after each rain.
- Plan the mulch. Choose a material from the table, the depth, and the date you will lay it, after the soil warms for warm-season crops.
- Go deeper Record it. Start the weekly water sheet: week of, rain, gallons given, soil check and notes. Fill one row a week for the season.
4. Your garden Your garden
5. Check your work Check your work
Criteria
- Can you state your garden's gallons for one inch, and show the multiplication?
- Did you time your hose at the setting you actually use, more than once?
- Does your plan say when you water (by the two-inch check), not only how much?
- If you use drip, did you compute a run time from the measured emitter rate, and split it into sessions?
- Is your mulch material and depth from the table, with a start date and a bare ring around stems?
- If you have a rain barrel, have you asked your local authority about its rules, and do you apply the water to soil only?
- Is there a weekly row in the water sheet?
Worked example
The Okafors' fictional plan meets every criterion that applies to them. Their gallons are shown as 64 x 0.623 = 39.9, and 27.9 after the week's rain. The hose was timed twice at their usual setting. Watering follows the two-inch check bed by bed, and they watered only the bed that was dry. Their straw mulch is 3 inches, inside both Iowa State's and Georgia's ranges, laid after the soil warmed, and held back from stems. They have no drip and no barrel. One weakness: they rely on a single gauge reading per week, so a storm on Sunday night lands in the following week's row. They add the date of each reading to the notes.
A container case shows the criteria working differently. Marisol Vega's fictional balcony garden is six containers: two of 10 gallons, two of 5 and two of 2. Gallons per inch do not apply to pots, so her plan is Penn State's: check each pot daily in hot weather and water until it drains from the bottom. She carries a 2-gallon can, and she records how many cans each pot takes to drain in her water sheet's notes. Water weighs 8.34 pounds a gallon, per the University of Arizona's sheet; whether the balcony carries the weight of wet pots is the building owner's question, which she asked in writing in Module 4.
Common mistakes
- Short, frequent sprinkling. A few minutes daily wets the top inch and leaves the root zone dry. Water the computed amount, less often.
- Watering by the calendar, not the soil. Two waterings a week in a cool, cloudy May can drown seedlings. The two-inch check comes first.
- Using the emitter label rate. A clogged or low-pressure emitter delivers less. Time a tablespoon.
- One long drip run on sandy soil. Water past the root zone is lost. Split the weekly time.
- Mulch against stems, or too early. Damp mulch against a stem invites rot and pests; mulch on cold soil in spring holds the cold in.
- Treating the barrel as drinking-quality water. It is not, under Rutgers' New Jersey guidance and in their test results.
What is still unresolved
The right weekly amount for your garden is not settled by any source; the published ranges run from 1 to 2 inches, and your two-inch checks recorded across a season settle it. Hose time changes with pressure and setup, so re-time after any change. Rain barrel rules and the safety of barrel water on food crops depend on where you live, and are settled by your state or local extension office and city, not by this course. A woody mulch left on the surface does not by itself call for fertilizer; if you dig woody material or sawdust into a bed, Module 9 covers how to work out a nitrogen amount from a label.