Growers Choice 4K 315W Single Ended CMH Lamp 4200K | 540 µmol/s Veg

Growers Choice 4K 315W single ended CMH lamp for veg and full-cycle rooms

Clone and veg rooms are where this lamp earns its keep. It is the 4200K lamp in the Grower's Choice single-ended range, part CMH-315W/942/PGZX18, sold as SKU GC315W4K01. The spec sheet lists 540 µmol/s and 33,000 lumens after 100 hours, or 110 lm/W. Colour rendering is given as 97 to 98, which is about as close to daylight as a discharge lamp gets. Rated life is 15,000 hours on ten-hour starts. Electrically it runs at 100V and 3.15A on a C182/O-rated or electronic ballast. The base is PGZX18, and the lamp is rated for open or enclosed fixtures in any burning position. Base temperature tops out at 250°C and bulb temperature at 350°C. Those are ordinary numbers for a 315W ceramic lamp. The warm 3100K lamp in the same line shares every electrical figure, so both run on the same ballast.

Where a cool single ended CMH bulb fits in the room

At this colour temperature the lamp sits on the edge between transitional and vegetative light. Growers run it over mother plants, fresh clones and young veg, and in single-lamp tents that go start to finish. The blue-rich output tends to keep internodes short and branching tight before flip. That high colour rendering also makes scouting easier, because leaf colour under it looks close to natural. Hang it higher over fresh cuttings and lower it as the canopy thickens and roots fill the pots. In our own ten-lamp CMH comparison it placed last on summed PAR, and its UV reading was the second lowest. The whole field sat within a narrow band on PAR, so last place still means a usable lamp. It is not the pick for maximum photons in flower, where the warm lamp in the range does better. Plenty of growers run one of each in a two-light room, which blends the two spectra without swapping bulbs at flip. Drive it with a low-frequency CMH ballast, since HPS and MH ballasts will not run it. It ships as a bare lamp, with the reflector and ballast sold separately.

Key Features

• 540 µmol/s Photon Flux: A published PPF figure makes veg-room planning a matter of arithmetic.
• CRI 97-98 Colour Rendering: Near-daylight rendering shows deficiencies and pests clearly during scouting.
• 4200K Veg and Full-Cycle Spectrum: Blue-rich light keeps young plants compact before the switch to flower.
• 15,000-Hour Rated Life: Rated at ten-hour starts, it covers many veg cycles before replacement.
• PGZX18, Any Burn Position: Fits standard single-ended 315W reflectors, open or enclosed, in any orientation.
• Same Ballast as the 3100K Lamp: Swapping to the warm lamp at flip needs no change of ballast or socket.

Technical Specifications