Can You Slow-Cook Prime Rib on a Grill?
Yes, and it works well on essentially any grill — gas, charcoal, pellet, or a kamado-style cooker — as long as you can create an indirect heat zone and hold it low and steady. The method is the same three stages regardless of grill type: a long, low cook to bring the roast most of the way to temperature, a short blast of high heat to build a crust, and a rest before slicing.
Prepping the Roast
A few optional steps improve the finished roast, though none are strictly required:
- Remove the silver skin from the back of the bones (if bone-in) using a paper towel for grip — it’s a tough membrane that doesn’t break down during cooking.
- The “secret trim”: run a sharp knife between the bones and the meat, cutting most of the way through without fully separating them. This lets rub reach the meat between the bones, not just the exterior, and can be tied back together with butcher’s twine before cooking.
- Score the fat cap lightly if it’s thick, so it renders more evenly.
Season the roast generously — a simple combination of oil, garlic, salt, pepper, and herbs like thyme and rosemary works well — and let it sit at room temperature for 2–3 hours before grilling. This isn’t unsafe; it just lets the roast come up gradually so it cooks more evenly than one going onto the grill straight from the fridge.
Setting Up Your Grill for Indirect, Low Heat
Regardless of grill type, the goal is the same: heat on one side, roast on the other, with the lid closed to hold a steady temperature around 250°F.
- Pellet smoker: Simplest option — set the temperature like an oven and let the grill do the work.
- Charcoal grill: Light the coals until they’re gray and ashed over, then bank them to one side. Adjust the vents until the grill settles around 250°F, and add wood chips or hickory briquettes for extra smoke.
- Big Green Egg / kamado: Add the plate setter to diffuse direct heat, adjust top and bottom vents to settle at 250°F, and add wood chips for smoke.
- Gas grill: See below — it takes a slightly different setup since there’s no natural indirect zone without turning some burners off.
- Oven (no grill available): Follow the same temperature stages, understanding you’ll lose the smoky flavor a grill or smoker adds.
Can You Cook Low and Slow on a Gas Grill?
Yes. Turn on only one burner and adjust it from low to medium until the grill stabilizes around 250°F, then place the roast on the unlit side so it cooks by indirect heat rather than sitting directly over the flame. To add smoke flavor, which a gas grill doesn’t produce on its own, use a pellet tube smoker filled with wood pellets, or make a foil pouch of soaked wood chips with a few holes poked in it and set it near the lit burner. Rotate the roast halfway through the low-heat stage so it cooks evenly, since a single-burner setup tends to run slightly hotter on one side.
The Three-Stage Method: Slow Cook, Sear, Rest
Stage 1 — Slow cook: With the grill holding around 250°F and the roast over indirect heat (fat side up, so rendering fat bastes the meat as it cooks), smoke until the internal temperature reaches about 110°F. For a 6 lb roast, this takes roughly 2 hours.
Stage 2 — Build the crust: Raise the grill temperature to 400°F, keeping the roast over indirect heat, and continue cooking until the internal temperature reaches 135°F for medium-rare — typically another 30 minutes. This higher heat is what develops the herb-and-fat crust that makes prime rib memorable, rather than leaving it pale from an entirely low-temperature cook.
Stage 3 — Rest: Pull the roast once it hits your target temperature, cover loosely with foil, and rest for 30 minutes before slicing. The internal temperature will continue climbing 5–10°F during this time, and cutting in early sacrifices a noticeable amount of juice to the cutting board.
How Long Does It Take?
As a starting point, a 6 lb rib roast takes about 3 hours total at 250°F: roughly 2 hours on low heat, 30 minutes on high heat to build the crust, and 30 minutes to rest.
For larger roasts, scale using this rule of thumb: 20–30 minutes per pound on low heat, plus 45–60 minutes on high heat to finish, plus the same 30-minute rest regardless of size. For a 10 lb prime rib at 225°F, that works out to roughly 3.5–5 hours on low heat, plus another 45–60 minutes on high heat and a 30-minute rest — call it 5–6.5 hours total, and always confirm with a probe thermometer rather than relying on the estimate alone, since roast shape and grill accuracy both affect the actual time.
Doneness Temperature Chart
Pull the roast at these internal temperatures, keeping in mind carryover heat will add another 5–10°F during the rest:
- 125°F–130°F: Rare
- 135°F–140°F: Medium-rare
- 145°F–150°F: Medium
- 150°F–155°F: Medium-well
- 160°F–165°F: Well done
Since a single prime rib roast naturally serves a range of preferences (the ends near the exterior cook further than the very center), you can pull individual slices for guests who want theirs more done and give them a quick extra sear on the grill just before serving, rather than overcooking the whole roast.
Resting and Slicing
Let the roast rest under loose foil for the full 30 minutes before cutting — this isn’t a step to rush, since it’s what keeps the roast juicy rather than pooling that moisture on the cutting board. If you did the “secret trim” between the bones, this is also the point to remove the twine and pull the rack of bones away cleanly before slicing the eye of the roast into portions.
FAQ
How long does it take to cook prime rib on a grill? For a 6 lb roast at 250°F, plan on roughly 3 hours total: about 2 hours on low heat, 30 minutes on high heat to build a crust, and 30 minutes to rest.
How long to cook my prime rib at 250 degrees? Expect roughly 20–30 minutes per pound during the low-heat stage at 250°F, followed by a shorter high-heat stage to build the crust and a 30-minute rest.
Can you cook low and slow on a gas grill? Yes — light only one burner, hold it around 250°F, and cook the roast on the unlit side. Add a pellet tube or a foil pouch of wood chips for smoke flavor.
How long will it take to cook a 10 lb prime rib at 225 degrees? Roughly 5–6.5 hours total, including the low-heat stage, the high-heat crust stage, and a 30-minute rest — always confirm doneness with a meat thermometer.
If you want a dedicated smoker version with a horseradish cream sauce on the side, see our recipe for smoked prime rib with horseradish cream.