Single-Ended vs Double-Ended LED Horticultural Bulbs

What single-ended and double-ended mean on a listing

On a grow light listing, single-ended and double-ended describe the connection layout of a replacement bulb and the fixture it fits. The words come from greenhouse lighting, where older lamps were either held at one end or between two sockets. An LED horticultural bulb that carries one of these names is sold for that same fixture layout.

The title usually states the connection word first, as in a single-ended or double-ended LED bulb. The bullet list then states the base or socket type, the fixture names it fits and the mounting parts in the box. When one of the two words is missing from the title, the maker page states the connection. The catalogue never adds a connection type that the title does not state.

How the ends fix into the fixture

Single-ended bulbs make their electrical connection at one end. The other end is usually a holder or a cap that seats in the fixture. Double-ended bulbs make contact at both ends, and the fixture holds the bulb between two sockets that face each other.

The fixture layout does not change when the lamp is LED. A double-ended fixture keeps two sockets, and the LED replacement bulb has a contact at each end. A single-ended fixture keeps one socket, and the LED replacement has one connection end.

The wattage stated for one bulb

A replacement bulb listing states the draw of one bulb, which is the figure to compare between listings. The wattage is the number the title or bullet list gives for a single bulb, not a pack total and not an equivalent figure. What watts cannot tell is the light output in PPFD or PAR; those numbers are on the maker page and the model manual.

When the listing names an LED chip maker or a control such as a dimmer or timer, those are features of the bulb. The listing does not need to restate the fixture fit; the connection word and the fixture names in the title cover that. Compare watts in two titles the same way, by reading the stated draw of one bulb in each.

Which jobs take a replacement bulb

A replacement bulb is the part that fits an existing fixture. The job is a greenhouse fixture with a lamp that needs replacing, or a single lamp socket in a desk or shelf light. In a grow tent, growers usually buy a quantum board or a bar light that arrives with a driver and hangers, rather than a replacement bulb.

For a shelf of houseplants or seedlings, linkable strips and panels are common fixture units. For a single potted plant on a desk, a grow light bulb in an existing lamp socket is the matching job. The choice is therefore whether the job needs a replacement part for a fixture that is already there, or a whole light unit for a new location.

• A greenhouse fixture with a lamp to replace: a replacement bulb fitted to the existing sockets.
• A desk lamp or shelf light with a standard socket: a grow light bulb with the matching base.
• A grow tent of 2x2 to 5x5: a quantum board, bar light or panel sold as a unit with a driver and hangers.
• A shelf of houseplants or seedlings: linkable strips or a panel sized to the shelf.

Fixture fit on the maker page

The listing states the connection type and the fixture names it fits. The maker page states the same fit in full, including the sockets or bases the bulb is made for and the mounting position. Read the maker page next to the listing before ordering.

The greenhouse versus indoor tent guide on this site compares the two settings, and the University of Minnesota Extension page on lighting for indoor plants is an official reference for how indoor plant light is described. The maker manual for the model is the place to read the fixture fit. The maker manual and local electrical rules come first when replacing a lamp in any fixture.

• The socket or base types the bulb is made for.
• The fixture names and models it replaces.
• The mounting position and the notes in the manual for the fixture.

Replacement bulbs versus fixture units

A greenhouse fixture takes a replacement bulb; a tent or shelf takes a fixture unit. The greenhouse versus indoor tent guide compares the two jobs, and the light distance guide explains a term that matters when mounting any light. What the catalogue cannot say is the light output in PPFD, PAR or DLI; read those on the maker page and the model manual.

For a dimmable or timer-controlled light, read the listing for the stated control and the maker page for how the control works. The dimmable guide lists fixtures that state a dimmer, and the timer guide lists fixtures that state a timer.

What to pick for your job

Questions

What does single-ended mean on a grow light listing?

Single-ended means the bulb makes its electrical connection at one end. The fixture holds that end in a socket, and the other end seats in a holder. Read the listing for the stated connection and the fixture names it fits, then confirm the fit on the maker page.

What does double-ended mean?

Double-ended means the bulb makes contact at both ends. The fixture holds the bulb between two sockets that face each other, the same layout as older double-ended greenhouse lamps. The listing states the connection word and the fixture names the bulb is made for.

Can a single-ended bulb fit a double-ended fixture?

No, the connection layouts are different. A single-ended bulb has one connection end and a double-ended fixture has two sockets. Check the listing and the maker page for the fixture names the bulb fits.

How do I read the wattage on a replacement bulb listing?

Read the wattage as the stated draw of one bulb. Compare that number between listings. The listing may also name the LED chip maker, a dimmer or a timer, which are features of the bulb. What watts cannot tell is the light output in PPFD or PAR; those numbers are on the maker page.

Do I need a special socket for a double-ended LED bulb?

The fixture already has the sockets. The double-ended bulb is made to fit that fixture layout, so read the fixture names on the listing and the maker page to confirm the fit. When a listing names a base, the base is the stated connection.

Where do I check the light output of a replacement bulb?

The listing states the connection, the wattage and the controls. The PPFD and PAR numbers, if the maker publishes them, are on the maker page and the model manual, not on the catalogue listing.