The garden workbench
Compare electrical input, lighting schedules and your own energy rate.
Use actual electrical input, not an “equivalent wattage” in the product title. Enter the usage rate from your electricity bill; $0.16 is an example, not your local tariff. If dimmed or thermostatically switched, a compatible energy meter gives a better measured starting point.
Two 40-watt fixtures running 14 hours daily use 1.12 kWh per day. Over 30 days that is 33.6 kWh, or about $5.38 at the example rate. These starting values demonstrate the arithmetic; they do not prescribe a lighting schedule for every plant.
Compare fixtures that can actually cover your growing area. A cheaper monthly bill is not a saving if seedlings receive inadequate light. Check the manufacturer's coverage and placement information, then match the schedule to the crop. Heat mats and greenhouse heaters can add costs of their own.
Daily kWh = actual watts per fixture × fixture count × hours per day ÷ 1,000. Period kWh = daily kWh × days. Energy cost = period kWh × your rate per kWh.
Virginia Cooperative Extension: Estimating Appliance and Home Electronic Energy Use describes this energy-cost method and the limits of nameplate wattage.
Use these guides to check the growing decisions behind your inputs.
Grow lights · 5 min read
Compare grow lights using canopy coverage, PPFD, daily light, and actual power draw. Understand why lumens and “equivalent watts” cannot predict plant results.
Read the guideGrow lights · 6 min read
Commission an indoor grow-light setup around canopy height, beam shape, shadows, adjustable mounting, and plant response.
Read the guideHydroponics · 7 min read
Compare the canopy, support, root-zone access, pollination work, and crop duration needed before moving from leafy greens to hydroponic tomatoes or peppers.
Read the guide
