Tools in This Collection
Drip Irrigation Calculator
Size a drip system to deliver adequate water based on plant needs and soil type
Drip Tape Calculator
Calculate emitter spacing and flow rates for raised bed drip tape rows
Rain Barrel Calculator
Estimate rain barrel storage capacity needs from roof area and rainfall
Rainwater Harvesting Calculator
Calculate annual rainwater collection from your roof area and local rainfall
Rain Garden Sizing Calculator
Determine rain garden area and depth to absorb runoff from impervious surfaces
Garden Water Timer Calculator
Convert target weekly water amount to irrigation controller run times
Greenhouse Heating Calculator
Size a greenhouse heater from structure dimensions and temperature differential
Grow Light Calculator (DLI)
Match grow light wattage and coverage to Daily Light Integral requirements
USDA Plant Hardiness Zone Lookup
Look up your USDA hardiness zone for plant selection and season planning
Plan Efficient Garden Irrigation and Water Systems
Most vegetables need 1-1.5 inches of water per week — that's 0.6-0.9 gallons per square foot. A 200 sq ft raised bed garden needs 120-180 gallons per week, or about 17-26 gallons per day. Hand watering delivers this inconsistently; a well-designed drip system delivers water directly to root zones at a steady rate, reducing disease pressure and water waste by 30-50% compared to overhead sprinklers.
Irrigation System Sizing
The Drip Irrigation Calculator sizes a system to deliver adequate water across your garden area based on plant water requirements, soil type, and emitter output. Drip emitters typically deliver 0.5-2 gallons per hour (GPH) — a 1 GPH emitter running 2 hours per day delivers 2 gallons to each plant. The Drip Tape Calculator calculates emitter spacing and flow rates for raised bed rows, where drip tape laid down the center of a 4-foot bed reaches plant roots on both sides.
The Garden Water Timer Calculator converts your target weekly water amount to run time per zone based on emitter output and zone size — a critical step when programming an irrigation controller.
Rainwater Collection
The Rain Barrel Calculator estimates storage capacity needs from your roof collection area and average rainfall. On average, you collect 0.6 gallons per square foot of roof per inch of rainfall — a 1,000 sq ft roof section generates 600 gallons from a 1-inch rain event. The Rainwater Harvesting Calculator shows how much annual collection you can expect and whether your storage capacity can satisfy your garden's water demand through dry periods.
The Rain Garden Sizing Calculator determines the area and depth of a rain garden needed to absorb runoff from a given impervious surface area — a 1,500 sq ft driveway typically needs a 150-300 sq ft rain garden to manage a 1-inch storm event.
Greenhouse and Indoor Growing
The Greenhouse Heating Calculator sizes a heater for any greenhouse structure based on dimensions and your local winter temperature differential. A 10x12 ft glass greenhouse in Zone 6 (maintaining 40°F inside when it's 20°F outside) needs approximately 8,000 BTU of heating capacity. The Grow Light Calculator (DLI) matches fixture wattage and coverage to your growing area based on Daily Light Integral — most vegetables need 20-30 DLI for productive growth. The USDA Plant Hardiness Zone Lookup identifies your zone for selecting perennial plants and planning season extension.
Frequently Asked Questions
How much water do vegetables need per week?
Most vegetables need 1-1.5 inches of water per week, equivalent to 0.6-0.9 gallons per square foot. Water-intensive crops like tomatoes, cucumbers, and squash need closer to 1.5-2 inches during fruiting. Leafy greens and root vegetables do well at the lower end of 1 inch. Drip irrigation is more efficient than overhead watering — it delivers water to root zones and reduces evaporation loss by 30-50%.
How much rainwater can I collect from my roof?
The general formula is: Roof collection area (sq ft) x Rainfall (inches) x 0.623 = Gallons collected. For a 1,000 sq ft collection area during a 1-inch rain, that's approximately 623 gallons. Most rain barrels hold 55-100 gallons, so a single event can overflow a barrel quickly. If you want to capture larger amounts, use a cistern or daisy-chain multiple barrels. The Rainwater Harvesting Calculator shows annual collection estimates based on your local rainfall data.
What size grow light do I need for an indoor garden?
Most vegetables need 20-30 DLI (Daily Light Integral) for productive growth. A 200W full-spectrum LED at 18 inches above plants typically covers a 2x4 ft footprint at around 25 DLI with 16 hours of photoperiod. Herbs and microgreens can thrive at 15-20 DLI. The Grow Light Calculator helps you match fixture output to your specific growing area and target DLI for your crops.
What is a rain garden and how big does it need to be?
A rain garden is a shallow depression planted with water-tolerant plants that captures runoff from rooftops, driveways, and other impervious surfaces. It allows water to infiltrate slowly rather than run off. The size depends on the drainage area and your soil's infiltration rate — sandy soils need smaller rain gardens, clay soils need larger ones. A general rule is that the rain garden should be 20-30% of the impervious surface area it drains.