How much water does a vegetable garden actually need?

Less than most people plan for, and rarely on a fixed schedule. Real demand depends on your soil, the weather, and how much rain has already fallen — a bed that got 5 mm of rain in the last three days often needs nothing. The honest way to size it is to measure rain and per-bed dryness for a season rather than assume every bed needs water every day.

Do I need a well to water my garden?

Often not, once you subtract the watering you'd skip after rain. Many gardens are sized around a worst-case daily demand that almost never actually happens. Before committing to drilling, it's worth measuring how often your beds are genuinely dry — you may find mains or stored water covers a far smaller real demand.

How often do garden beds really need watering?

There's no universal number; it varies by bed, soil, plant, and recent rain. A capacitive soil probe removes the guesswork by telling you when a specific bed is actually dry instead of when the calendar says to water. In Siltwell that's a per-bed alert when the two most recent readings both fall below the bed's threshold.

Can I skip watering after rain?

Usually yes. If about 5 mm or more fell in the last few days, most beds are still holding moisture and watering just wastes it. Siltwell's garden-level guidance reads your station's rain gauge plus the forecast and tells you to hold when real rain has covered you or is coming.

August 17, 2026

Before You Drill a Well for the Garden, Know How Little You'll Actually Pump

Search "water well drilling" and every result is a contractor page: cost per foot, permits, casing, pump sizing. All useful if you've already decided to drill. None of them asks the question that actually decides how big a well you need — or whether you need one at all: how much of your watering demand is real, and how much is imaginary because you've never measured rain or per-bed dryness.

Most garden water budgets are sized for a day that rarely comes

When people estimate garden water demand, they tend to multiply the worst case by everything: every bed, every day, all season. That's how you end up sizing a well — and its pump, and its storage — around a number the garden almost never actually asks for. In practice, beds are dry far less often than a daily schedule assumes, because rain keeps interrupting the plan and different beds dry out at different rates.

The problem is that the two things that shrink real demand — rain that already fell, and beds that aren't actually dry yet — are exactly the two things most gardeners never measure. So the budget stays inflated, and the well gets sized to match a fiction. Before you drill for a number that big, it's worth measuring the honest one first.

Rain you already caught is water you don't need to pump

The first chunk of imaginary demand is watering on days when it recently rained. A single decent shower can cover a garden for days, and watering on top of it is water pumped for nothing. But "it rained" is fuzzy — a light sprinkle isn't the same as a soaking, and most people are guessing.

Siltwell replaces the guess with a garden-level watering signal built from your station's own rain gauge plus the forecast. It reads three plain states:

Covered — about 5 mm or more fell in the last three days, so hold off; the ground is still holding it.
Hold — 5 mm or more is in the forecast for the next day or two, so wait for it rather than pump now.
Water — no real rain behind you or ahead, so this is a genuine watering day.

This guidance is garden-wide, not per-bed — it's answering "has real rain covered the garden?" With a connected station it uses your gauge's own readings; without one it falls back to the forecast alone. Tally up a season of "covered" and "hold" days and you'll usually find a surprising fraction of your assumed demand simply evaporates.

Per-bed dryness trims the rest

The second chunk of imaginary demand is watering beds that aren't dry. A schedule treats every bed the same; soil doesn't. A shaded bed of established perennials and a sun-baked bed of seedlings drain at completely different rates, and watering the whole garden because one corner looked thirsty is how the budget balloons.

A buried capacitive soil probe mapped to a bed turns that into a number. Siltwell fires a "this bed is low" alert when the bed's two most recent readings are both below its threshold — the default is 25%, which you tune per bed once you've watched how that particular soil dries. Two readings rather than one, so a single odd blip doesn't set off a false alarm. The plain-language version is: it tells you which bed to water and which to skip, so you're only pumping for the beds that genuinely need it.

If you already know you'd rather run a pump only when beds are actually dry, the pump-only-when-beds-are-dry guide goes deeper on wiring that logic into your routine. Worth being clear up front, though: Siltwell alerts and advises — it doesn't run the pump or open a valve. The dry-bed alert lands on your phone; the decision and the switch are still yours.

Measure a season before you commit to the drill

The honest sequence is cheap and slow, which is the opposite of a drilling estimate. Watch the rain guidance to learn how many days are already covered. Put a probe in your thirstiest bed and your steadiest one to learn how often each actually crosses "dry." After a season you'll have a real demand figure — one built from measured rain and measured dryness, not from a worst-case multiplication.

That number is what should size a well, storage tank, or even the decision to skip drilling entirely and stay on mains or a rain barrel. It's a lot easier to justify a big capital project — or talk yourself out of one — when the demand behind it is measured rather than assumed.

Curious how your spot compares before you buy any hardware? The public microclimate checker compares the forecast low to what nearby home stations recorded over recent nights and reports how much cooler or warmer your area tends to run — an area indicator, not a guaranteed reading for your yard, but a free first look.

Connecting a station and per-bed soil alerts are part of Siltwell Pro ($22/year, with a 14-day free trial); the free tier still lets you log watering by hand and gives forecast-based guidance. Siltwell supports Ecowitt, Ambient, Tempest, and Davis — note a Tempest has no soil sensor, so you'd add an Ecowitt WH51 probe alongside it. Gear we mention is linked with disclosed affiliate links on the setup page — here's how to connect a station and pick a probe.

A rain gauge and a soil probe narrow the guesswork; they don't repeal the weather. A heat wave can still dry a bed faster than any three-day rain total suggests, and a probe reads one spot in one bed, not the whole garden. Use the measurements to delete the obvious waste — watering after a soaking, pumping for beds that aren't dry — and let a season of honest numbers, rather than a worst-case guess, decide how much water you really need to find.

Common questions

How much water does a vegetable garden actually need?: Less than most people plan for, and rarely on a fixed schedule. Real demand depends on your soil, the weather, and how much rain has already fallen — a bed that got 5 mm of rain in the last three days often needs nothing. The honest way to size it is to measure rain and per-bed dryness for a season rather than assume every bed needs water every day.
Do I need a well to water my garden?: Often not, once you subtract the watering you'd skip after rain. Many gardens are sized around a worst-case daily demand that almost never actually happens. Before committing to drilling, it's worth measuring how often your beds are genuinely dry — you may find mains or stored water covers a far smaller real demand.
How often do garden beds really need watering?: There's no universal number; it varies by bed, soil, plant, and recent rain. A capacitive soil probe removes the guesswork by telling you when a specific bed is actually dry instead of when the calendar says to water. In Siltwell that's a per-bed alert when the two most recent readings both fall below the bed's threshold.
Can I skip watering after rain?: Usually yes. If about 5 mm or more fell in the last few days, most beds are still holding moisture and watering just wastes it. Siltwell's garden-level guidance reads your station's rain gauge plus the forecast and tells you to hold when real rain has covered you or is coming.

Related guides

Free planting tools

When to plant — the last date to sow each crop before your fall frost
Microclimate checker — how much colder your yard runs than the forecast
GDD estimator — whether a crop will ripen where you are