Watering Guide
Pick what you are growing and where, and get inches per week, gallons for your bed, and how many days to split it over.
Watering calculator
A standard raised bed is 4 ft by 8 ft. Measure the soil surface, not the outside of the frame.
Measure across the top of the pot. A 5 gallon bucket or grow bag is about 12 inches across, a half wine barrel about 26 inches.
Subtracted from what you need to supply. Leave at 0 if you do not know. A cheap straight-sided rain gauge pays for itself in one season.
Change the assumption: target inches per week
Every figure on this page starts from one number: the inches of water per week this plant wants in open ground in warm weather. Published figures for the same crop genuinely differ, usually across a range of about half an inch, so if your extension office or your own record says something else, put it here and the rest of the math follows it.
Your watering plan
The two rules that beat any calculator
The finger test
Push a finger into the soil up to the second knuckle, about two inches, next to the plant rather than in the watering ring. If it comes out with soil clinging to it and feels cool and damp, do not water. If the top two inches are dry and crumbly, water.
For containers, check at one inch instead, and learn the lift test: pick the pot up right after a thorough watering and again two days later. The difference in weight is more reliable than anything you can see.
For lawns and deep beds, push a long screwdriver into the ground. It slides easily through moist soil and stops at the dry layer. Where it stops is how deep your last watering actually reached, which is usually less than you think.
Deep and infrequent, not shallow and daily
Roots grow where the water is. A light daily sprinkle keeps the top inch wet and teaches every root in the bed to live in that inch, which is the first thing to dry out and the first thing to overheat. The same total water delivered in two or three long soakings pulls roots down to six or eight inches, where the soil stays cool and damp for days.
The practical version: water until the moisture has reached the bottom of the root zone, then leave it alone until the top two inches dry out. That is what the day count in the calculator above is doing.
There are two real exceptions. Seeds and new transplants have no deep roots yet, so they need light water once or twice a day until they do. And containers hold a fixed volume of soil, so once it is full you cannot water any deeper. You can only water again sooner.
Overwatered or underwatered? They look almost identical
A wilting plant is the most misread signal in gardening, because too much water and too little water both produce a limp plant with yellowing leaves. The difference is in where you look. Check the soil first, then work down this table.
| What you check | Too much water | Too little water |
|---|---|---|
| Time of day it wilts | Wilted in the cool of the morning too, and it does not recover overnight | Wilts in the afternoon heat and perks back up by evening, which on a hot day is normal and not a problem |
| Soil two inches down | Still dark and wet days after watering | Dry, pale and crumbly, and pulling away from the bed edge or pot wall |
| Which leaves yellow first | Lower and older leaves, spreading upward, whole plant looks dull | Outer edges and tips first, working inward |
| How the leaf edges feel | Soft, limp, sometimes with brown mushy patches | Dry, brown, brittle, crumbles between your fingers |
| New growth | Soft, pale, small, may blacken at the tip | Small, slow and thin, and it stops rather than deforms |
| Stem at the soil line | Dark, soft or mushy, sometimes with a sour smell | Firm and normal even while the plant above is limp |
| Soil surface | Green algae, white mold, or a cloud of fungus gnats | Cracked, crusted, and water runs off instead of soaking in |
| Roots, if you can see them | Brown, soft, smelly, and the outer skin slips off when pinched | Dry, brittle and pale, with very few white tips |
| Fruit | Split or cracked skin, bland flavor, and blossom drop | Blossom end rot, small and bitter fruit, and flowers that drop before setting |
| Speed of decline | Slow, over a week or more, and watering more makes it worse | Fast, over a day or two, and a deep soak visibly helps within hours |
Blossom end rot is the one people always get backwards. The dark sunken patch on the bottom of a tomato or squash is a calcium problem, but almost never a calcium shortage in the soil. Calcium only moves through the plant with water, so uneven watering, long dry spells broken by heavy soakings, is what causes it. Adding calcium rarely fixes it. Watering steadily usually does.
How this is calculated
The whole calculation rests on one conversion, and it is worth memorizing: one inch of water spread over one square foot is 0.623 US gallons. That comes straight from the geometry, not from a study. One square foot is 144 square inches, so one inch deep over it is 144 cubic inches. A US gallon is 231 cubic inches, so 144 divided by 231 is 0.6234 gallons.
From there: gallons per week = inches per week × square feet × 0.623. Everything else on this page is choosing the inches figure. The base figure is what the crop wants in open ground in ordinary warm weather, and it is then multiplied by a situation factor and a weather factor, both of which are shown to you on every result so you can argue with them.
The situation factors are 1.0 in-ground, 1.3 raised bed and 2.2 container. A raised bed drains from the bottom and dries from four exposed sides, so it needs roughly a third more than the same area of open ground. A container is the same problem taken to its limit: a small volume of fast-draining mix, warm on all sides, packed with roots. The weather factors are 0.7 cool, 1.0 warm, 1.35 hot and 1.7 in a heat wave, which track how fast water leaves the soil and the leaves as temperature and wind rise.
What this cannot know. Your soil type is the biggest missing variable: sand may need the same total split into more, smaller waterings, and heavy clay holds water so well that the same schedule drowns things. Mulch cuts evaporation substantially. Shade, wind exposure and plant size all move the number. Treat the result as a starting point that gets you close on day one, and let the finger test correct it from day two. Published figures for the same crop genuinely differ by around half an inch a week, which is why the base number is editable rather than hidden.
Water needs by crop
Base figures for open ground in ordinary warm weather. Multiply by 1.3 for a raised bed and by about 2.2 for a container, then by the weather factor. Root depth is why two crops that want the same inches still get watered on different days.
| Crop | Inches per week | Root depth | What to watch |
|---|---|---|---|
| Tomatoes | 1.5 | 24 in | Steady is everything. Swinging between dry and soaked causes both cracking and blossom end rot. |
| Peppers and eggplant | 1.25 | 18 in | Drop flowers if they dry out during fruit set. |
| Cucumbers | 1.5 | 12 in | Shallow rooted and thirsty. Any check in water makes the fruit bitter. |
| Summer squash and zucchini | 1.5 | 18 in | Midday wilt on huge leaves is normal. Judge by the soil. |
| Winter squash and pumpkins | 1.5 | 24 in | Ease off as the fruit matures to improve storage life. |
| Melons and watermelon | 1.5 | 24 in | Cut water back in the last two weeks before harvest for sweeter fruit. |
| Beans | 1.0 | 18 in | Most sensitive during flowering and pod fill. |
| Peas | 1.0 | 18 in | A cool-weather crop. Water need falls fast once it warms up and they finish. |
| Sweet corn | 1.25 | 24 in | Critical from tasseling to silking. A dry week then means missing kernels. |
| Lettuce and salad greens | 1.25 | 8 in | Very shallow. Little and often is genuinely correct here. |
| Spinach | 1.25 | 10 in | Bolts when stressed by heat and dryness together. |
| Kale and chard | 1.0 | 12 in | Tougher than they look, but the leaves get bitter when dry. |
| Broccoli, cabbage, cauliflower | 1.25 | 18 in | Uneven water splits cabbage heads and makes broccoli button early. |
| Carrots, beets and turnips | 1.0 | 18 in | Dry then wet is what splits roots. Keep the top inch damp while germinating. |
| Radishes | 1.0 | 6 in | Fast, shallow and unforgiving. Dryness makes them woody and hot. |
| Potatoes | 1.25 | 18 in | Most important from flowering onward, when tubers are sizing up. |
| Onions and garlic | 1.0 | 10 in | Stop watering entirely once tops start falling over, or they store badly. |
| Basil and soft herbs | 1.0 | 12 in | Wilts dramatically and recovers completely. Judge by soil, not by drama. |
| Rosemary, thyme, sage, oregano, lavender | 0.5 | 18 in | The most commonly killed plants in any garden, almost always by kindness. |
| Strawberries | 1.25 | 10 in | Shallow rooted. Water at soil level to keep fruit and crowns dry. |
| Blueberries | 1.5 | 12 in | Shallow fibrous roots that dry out fast. Mulch heavily. |
| Raspberries and blackberries | 1.25 | 18 in | Need the most while the fruit is swelling. |
| Seedlings and new transplants | 1.25 | 4 in | The one case where light and frequent is right. Never let the top inch dry out. |
| Annual flowers and bedding | 1.0 | 10 in | Flowering stops first when they are short of water. |
| Established perennial border | 0.75 | 24 in | Far tougher than annuals once past the first year. |
| New tree or shrub, first year | 1.5 | 18 in | Water the root ball itself, not the ring around it, for the first season. |
| Established tree or shrub | 0.5 | 36 in | Deep and rare. Water at the drip line, not the trunk. |
| Lawn, cool-season grass | 1.25 | 12 in | Going dormant and brown in a summer drought is survival, not death. |
| Lawn, warm-season grass | 1.0 | 18 in | Deeper rooted and more drought tolerant than cool-season turf. |
| Succulents and cactus | 0.25 | 12 in | Soak thoroughly, then let the soil dry out completely before the next one. |
Keep planning
Watering is the daily job. These are the ones that set the year up.
Common questions
How much is one inch of water, really?
It is 0.623 gallons for every square foot you are covering. A 4 ft by 8 ft raised bed is 32 square feet, so one inch across it is about 20 gallons. That number surprises most people the first time, and it is the main reason gardens are underwatered: a two minute pass with a hose wand does not deliver anything close.
The easiest way to check is to put a straight-sided container, a tuna can is the classic, in the bed while you water, and see how long it takes to fill to one inch. Then you know your own setup in minutes rather than gallons, and you never have to do the math again.
Is it better to water in the morning or the evening?
Morning, clearly, and early. The plant gets water before the heat of the day, less is lost to evaporation than at midday, and the leaves dry off quickly, which matters because leaves that stay wet overnight are how most fungal disease starts.
Evening is the second choice and it is a real second choice, not a disaster. If evening is the only time you have, water at the soil level rather than over the leaves. Midday is the least efficient time, but the old warning that droplets on leaves scorch them in the sun is a myth for garden plants. Watering a wilting plant at noon is always better than letting it sit until evening.
My plant wilts every afternoon. Is it thirsty?
Probably not, if it recovers by evening. Big-leaved plants such as squash, cucumbers and hydrangeas transpire faster than their roots can pull water on a hot afternoon, and they wilt to reduce the surface area losing water. It is a working response, not a failure, and it corrects itself when the sun drops.
The signal that matters is wilting in the morning. If the plant is limp at 8am, after a whole cool night to recover, something is genuinely wrong, and it is as likely to be too much water and rotting roots as too little. Check the soil two inches down before you reach for the hose.
How often should I water containers?
In ordinary summer weather, most containers need water once a day, and in a heat wave small ones need it twice. That is not a failure of your technique. A pot holds a fixed volume of fast-draining mix, it is warm on every side, and once roots fill it there is very little water-holding soil left.
Water until it runs freely out of the drainage holes, every time. Anything less wets only the top and leaves a dry core the roots cannot use. If a pot has dried out completely and water is running straight through without wetting anything, stand it in a tray of water for half an hour to rewet the mix from below.
Does rain count toward the weekly total?
Yes, but only if you measure it. Put a straight-sided rain gauge where nothing overhangs it, and subtract what it caught from the week's target. Weather app rainfall figures are for the reporting station, not your yard, and summer storms are famously local.
Two things to watch. A brief heavy downpour on dry, crusted soil mostly runs off, so half an inch on the gauge may be a quarter inch in the root zone. And containers, plants under eaves, and anything under a dense leaf canopy catch far less than the open ground a few feet away. If yours are sheltered, leave the rainfall figure at zero.
Should I water differently in sandy soil or clay?
Yes, and this is the biggest thing the calculator above cannot see. Sandy soil holds roughly half the water clay does for the same depth, so the same weekly total has to be split into more, smaller waterings or most of it drains past the roots. Heavy clay is the opposite: it accepts water slowly and holds it a long time, so the same schedule that suits sand will keep clay soggy.
On clay, water slowly enough that nothing puddles or runs off, and wait longer between soakings. On sand, water more often and mulch heavily. In both cases the finger test tells you what your soil is actually doing far faster than any table.
Does mulch really make that much difference?
Yes. Two to three inches of organic mulch, straw, shredded leaves, bark or compost, substantially cuts evaporation from the soil surface, keeps root-zone temperatures down, and stops the crusting that makes water run off instead of soaking in. In a hot, windy summer it is the single cheapest change you can make to your water use.
Keep it pulled back an inch or two from stems and trunks so the bark stays dry, and lay it after the soil has warmed in spring rather than over cold wet ground.
Can I trust these numbers for my garden?
Treat them as a good starting point rather than a prescription. The figures come from standard vegetable and ornamental water-use guidance, and published values for the same crop genuinely disagree by around half an inch a week, which is why the base number on this page is editable rather than hidden.
What the calculator cannot know is your soil texture, your mulch, your wind exposure, how much shade you get and how big your plants are right now. Use the number for the first week, check with a finger, and adjust. After two weeks your own record beats any table, including this one. Your county cooperative extension office publishes figures tuned to local soils and climate and will answer questions for free.