Replacement HPS grow bulbs (high pressure sodium) for reflectors with an E40 socket: Philips Son-T 250 W, Son-T GreenPower 400 W and 600 W, and Osram Plantastar 400 W. Their yellow-orange light is designed for flowering. A bulb should be replaced every 1–2 years and must match the wattage of the ballast; complete kits are among the HPS grow light kits.
| Bulb | Wattage | Typical grow tent |
|---|---|---|
| Philips Son-T | 250 W | 60x60 cm |
| Philips Son-T GreenPower | 400 W | 80x80 cm, at most 100x100 cm |
| Osram Plantastar E40 | 400 W | 80x80 cm, at most 100x100 cm |
| Philips Son-T GreenPower | 600 W | 100x100–120x120 cm |
An HPS bulb loses light gradually: it still ignites, but after 1–2 years of regular use it gives out noticeably less, and the plants receive less without you seeing it. It is better to replace it before a new flowering cycle than to wait for it to fail. Signs of end of life: slow ignition, a lamp that switches itself off and on again, blackened glass at the ends.
If you are thinking of switching to LED, the comparison and running costs are on the grow lights page.
Prices are in Swiss francs including Swiss VAT. We ship throughout Switzerland with Swiss Post, and bulky parcels go by courier. For help with finding the right bulb for your ballast, ask the Gro.w.LaB team: contact us by email, call +41 79 359 67 58 or visit the shop in Quartino by appointment.
Every 1–2 years of regular use, ideally before a new flowering cycle. The bulb still lights up but gives out less light.
A standard HPS bulb gives yellow-orange, red-rich light designed for flowering. The Agro version adds a share of blue and is also used in the vegetative stage.
No: bulb and ballast must have the same wattage. You need a 600 W ballast, or an adjustable ballast that goes up to 600 W, set to that value.
Both have an E40 socket: first match the wattage of your ballast, then pick the model. At 400 W, both the Philips Son-T GreenPower and the Osram Plantastar fit.
