Guide ·
Grow light distance chart
Hang height is a starting point. These ranges are for modern LED bars, not a BAVAGREEN PPFD map and not an HPS clearance.
Hanging height depends on the fixture, the growth stage, and how warm the leaves are. A chart can give you a place to begin. It cannot tell you the intensity at the canopy of a specific lamp. Use the ranges below for a modern LED bar, then adjust with the dimmer and with the plants in front of you. Ask BAVAGREEN for the PPFD map of the model you buy. That map overrides this page.
| Stage | Starting hang height | Intensity |
|---|---|---|
| Seedlings and clones | 60–75 cm (24–30 in) | Dim well down. High intensity at this stage stresses young plants. |
| Vegetative | 45–60 cm (18–24 in) | Raise intensity as the canopy fills in. |
| Flower | 30–45 cm (12–18 in) | Follow the fixture PPFD map. Closer is not automatically better. |
What the three ranges are for
Seedlings and clones are thin. A high intensity at this stage stresses them even when the lamp is a good one. The starting band is 60–75 cm, about 24–30 inches, with the dimmer well down. You are keeping the light gentle while roots and the first true leaves establish. If the stems stretch hard toward the lamp, they want a bit more intensity or a spectrum with enough blue, not a lamp dropped onto the leaves.
Vegetative growth is when the canopy fills. The starting band is 45–60 cm, about 18–24 inches. Raise intensity as the floor of leaves closes. A dimmable bar earns its place here: you can add power without changing hang height every few days, then move the lamp once the tent gets crowded.
Flower is the shortest starting band, 30–45 cm, about 12–18 inches, and it is the stage where a generic chart is most likely to be wrong for your fixture. Follow the PPFD map. Closer is not automatically better. Bleached tops, taco leaves, and a canopy that stops gaining are signs to dim or to raise the lamp. A dense, even canopy at a moderate hang is a better result than a hot spot in the center.
These bands are industry starting ranges for modern LED bars. They are not BAVAGREEN measurements. They are not clearances for an HPS lamp. Sodium bulbs run hotter at the glass, and the distances in that lamp's manual are the ones that apply. The LED and HPS comparison covers the heat difference. If an older lamp is still in the tent, do not reuse this table for it.
Two published bars do not hang as twins
A 240W four-bar and a 600W six-bar can share a diode family and still put different intensity on the leaves at the same distance. BA-600W-PLUS is listed at 600 W, about 2.90 µmol/J at the fixture, and 1740 µmol/s, for a 120×120×200 cm tent. The 240W PLUS is listed at 240 W, the same fixture efficacy style, and 696 µmol/s. At one hang height the 600W bar delivers more light. That is why the dimmer exists, and why a 4×4 lamp is the wrong starting point in a 2×2.
In the 4×4 kit you have about 200 cm of tent height. A 30–45 cm flower hang still leaves room above the pots if the plants stay trained. In a short 60×60 frame, published heights include 140 cm and 180 cm, and the ceiling arrives sooner. The 2×2 kit is quoted in the 240W class so you are not trying to dim a 600W commercial bar inside a closet. Confirm the tent height on that packing list.
The 80×80 kit is 180 cm tall with the 240W bar. That is a comfortable tent for the vegetative band on this chart, and you still confirm the PPFD map rather than trusting the generic numbers. The 3×3 kit sits between those floors. Its exact bar is confirmed on inquiry, and the hang height should be read from that model's map once the model is chosen.
Dimmer first, tape measure second
New growers move the lamp because the tape measure is visible and the dimmer is a knob they have not used. Do the opposite while the plants are small. Set a starting height from the table, dim down until the leaves look comfortable, and keep that height for a few days so you can see the trend. Pale, tight growth can mean too much light. Long internodes can mean too little light, or a lamp that is too far for the power you have selected, or a tent that is simply too warm.
Leaf temperature is the check the chart cannot do. If the room is already hot, raising intensity at 30 cm will cook the tops even when a forum post says that distance is "flower height." Exhaust has to be in place before you chase a number. Complete kits include an inline fan and a carbon filter for that reason. The 80×80 set publishes a 4-inch EC inline fan and a 6-inch clip-on fan. The 2×2 kit publishes the same inline size. The 3×3 and 4×4 kits publish a 6-inch inline fan at 410 CFM.
Watch the corners as well as the center. A bar layout spreads diodes across the floor. A single reading under the middle of the fixture will look stronger than a reading near the wall. If the edge plants stretch while the center plants stall, you may be too close, the tent walls may not be reflective, or the fixture may be small for the floor. Matching the lamp to the floor is the job of the tent-light guide. The 4×4 watts guide explains why 600W is the published middle for that one size.
UV, far-red, and the channels that stay off
UV and far-red change the story if you leave them on at full power for the whole cycle. On BAVAGREEN Pro bars those channels have their own control. The white and 660 nm red base is the light you hang by this chart. Far-red at 730 nm and UV, listed at 385 nm on the 600W sheet, are supplemental. Keep them off in early growth unless you have a reason and a map that includes them. The UV and far-red page is the product explanation. The LM301H EVO page explains why the fixture efficacy sits near 2.90 µmol/J even when the white diode is listed higher: the extra diodes and the driver are inside the fixture number.
How to ask for the map
Tell sales the model, or the tent if you have not chosen the model. For a published fixture, name BA-600W-PLUS or the 240W bar. For a kit, name the 2×2, the 3×3, the 4×4, or the 80×80 set. Ask for the PPFD map at the hang height you intend to use, and ask which height the factory uses for flower on that sheet.
Until that map arrives, start inside the ranges in the table, dim for seedlings, and move in small steps. A 5 cm change is enough to judge. Write down the height and the dimmer setting when the plants look right, and repeat that setting the next time you run the same fixture. The chart gets you started. The map, and the leaves, finish the job.