Key Facts: Garden, Lawn & Grow-Light Gear
This page is Grow Lab's maintained fact reference — the specs and USDA/extension-service reference data our guides are built on, restated in plain prose. We report equipment specifications and reference frameworks, never pesticide, chemical-application, or plant-health-outcome claims.
PPFD and DLI for grow lights
PPFD (Photosynthetic Photon Flux Density, µmol/m²/s) measures how many photosynthetically-useful photons reach your plant's leaf surface — it is the honest metric, not "equivalent watts" or lumens, neither of which correlates reliably with usable light. DLI (Daily Light Integral, mol/m²/day) accumulates PPFD over your total daily light hours and is the number that best predicts growth, since the same PPFD for 12 hours delivers roughly double the DLI of 6 hours. Mounting height changes PPFD significantly — always check a manufacturer's PPFD-at-distance chart, or measure it yourself with a PAR meter. Full detail in What PPFD Do My Plants Need? and Are "Equivalent Watts" Meaningless?, with the normalized reference table at The Garden Gear Numbers.
Mower deck size and cordless runtime
Deck size should scale to yard size: a 21in deck suits lawns under about a quarter-acre, 30-42in decks suit a quarter- to half-acre, and 42in+ riding decks suit above about half an acre. For cordless mowers, runtime is set by the battery's amp-hour (Ah) rating combined with the deck's power draw, not by the voltage class alone — a 40V mower with a small battery kit can run out mid-lawn on a property a larger-Ah kit would finish easily. Details in What Mower Deck Size For My Yard? and Lawn Care Starter Kit.
Hose diameter, GPM, and burst pressure
5/8in is the standard garden hose diameter; 3/4in moves meaningfully more GPM at the same water pressure but is heavier and often needs adapters for standard fittings. Flow rate (GPM) drops as hose length increases at a fixed pressure — a 100ft run delivers noticeably less GPM than the same diameter cut to 50ft. Burst pressure (the pressure at which the hose wall is expected to fail) is a separate spec from kink-resistance, which describes the wall material's resistance to collapsing when bent. See How Many GPM Does My Hose Deliver?.
Sprinkler coverage and precipitation rate
A sprinkler's advertised coverage area (e.g., "4,000 sq ft") describes reach, not evenness — precipitation rate (inches of water applied per hour) typically declines from the head outward. Calculating a watering run-time means measuring your specific sprinkler's precipitation rate (via a catch-cup test) and dividing your weekly watering target (commonly ~1 inch/week for lawns, a general reference, not a universal rule) by that rate. Full walkthrough at How Long Should I Run a Sprinkler?.
Raised bed depth by crop root depth
Bed depth should match your crop's root depth: shallow-rooted crops (lettuce, herbs, strawberries) suit 6-12in; medium-rooted crops (bush beans, peppers) want 12-18in; deep-rooted crops (tomatoes, squash, carrots, potatoes) want 18-24in or more. A bed on native soil lets roots extend below the walls; an elevated bed on legs or a hard surface makes depth a hard limit. Details in How Deep Should a Raised Bed Be?.
NPK numbers and soil pH
The three numbers on a fertilizer label (e.g., 10-10-10) are the guaranteed percentage, by weight, of Nitrogen (N, drives leafy growth), Phosphorus as P2O5 (P, supports roots and flowers/fruit), and Potassium as K2O (K, supports vigor and stress tolerance) — always in that fixed N-P-K order. Soil pH (0-14 scale, 7 neutral) affects whether nutrients already in the soil are chemically available to roots; most vegetables and lawn grasses prefer roughly pH 6.0-7.0, while acid-loving plants like blueberries want roughly pH 4.5-5.5. Details in What Do the NPK Numbers Mean?.
Bypass vs anvil pruners
Bypass pruners use two curved blades that pass like scissors, giving a clean cut suited to living, green stems. Anvil pruners use a single blade closing onto a flat plate, crushing rather than slicing — correct for dead or dry wood, but a poor choice on live tissue since crushing can bruise the stem at the cut. Full comparison at Bypass vs Anvil Pruners.
USDA hardiness zone framework
USDA Plant Hardiness Zones classify regions into 13 zones (with "a"/"b" half-zones) based on average annual extreme minimum winter temperature, indicating whether a perennial is likely to survive winter outdoors in a given area. Zones are not frost dates and don't capture microclimates, soil type, or summer heat — always check your specific zone via the USDA's own lookup and pair it with local frost-date data for planting timing. Seed-starting heat mats warm soil relative to ambient room temperature (+10-20°F above ambient), not to a fixed number, so pairing a mat with a thermostat controller is the only reliable way to hit a specific soil-temperature target for germination.
How these facts are maintained
These facts are drawn from published USDA and cooperative-extension material, manufacturer specifications, and industry-standard measurement conventions (PPFD/DLI, GPM, NPK labeling), reviewed against our guides and updated on the date shown above when specs or the market change. We do not publish prices or star ratings, every pick names an honest drawback, and we stick to equipment/reference facts — never pesticide, chemical-application, or plant-health-outcome claims. Our full methodology is at How We Evaluate Garden & Lawn Gear.