Hood vs Bare Bulb

The hood vs bare bulb decision was a major HPS cannabis cultivation discussion for decades, though it has become less relevant as LED lighting (which is inherently directional) replaced HPS in most cultivation. The configurations: (1) Hooded fixtures — HPS or MH bulbs mounted horizontally inside a reflective metal hood that captures upward and side light, redirecting it downward to the canopy; standard hood designs include the Cooltube (glass tube around bulb for water cooling), Adjust-A-Wing (curved reflective wings adjustable for coverage area), Magnum XXXL hood (large flat reflector), and standard cone-shaped reflectors. Hooded fixtures direct 70-85% of bulb output downward to the canopy with rest absorbed by hood walls or escaping sideways. (2) Bare bulb / vertical setups — HPS bulbs mounted vertically without hoods, allowing 360-degree light radiation outward from the bulb; plants surround the bulb in a circular pattern; this maximizes total useful light by eliminating hood absorption losses. Bare bulb advantages: better total light utilization (no hood absorption), excellent for tall plants where canopy is vertically distributed, maximizes bulb life (better cooling without enclosed hood), traditional choice for vertical farming systems. Bare bulb disadvantages: requires plants arranged 360 degrees around bulb (impractical for SCROG and standard horizontal canopies), lower PPFD at any specific point because energy spreads in all directions, hard to achieve uniform light distribution, requires larger overall grow space. Hooded fixture advantages: optimized for horizontal canopy coverage (most common cannabis cultivation configuration), higher PPFD directly under the bulb, better light control and direction, easier to manage in tents and small rooms. Hooded fixture disadvantages: hood absorbs 15-30% of total bulb output, hood traps heat increasing bulb operating temperature, reflective surfaces degrade over time reducing efficiency, complex hood designs cost more than bare bulb sockets. The shift to LED has largely eliminated this discussion — LED chips are inherently directional and don't require external reflectors to control light pattern; modern LED fixtures simply optimize chip placement and lens design for the desired coverage pattern. Vertical farming with LED has also evolved past the hood-vs-bulb framework, using bar-style LED arrays mounted vertically with directional optics. The hood-vs-bare-bulb debate is now mostly historical, relevant only for legacy HPS operations.