Look up roasting times for broccoli and you'll find 12 minutes on one site and 25 on another. Neither is wrong — they're written for different oven temperatures and different cut sizes, and most charts don't say which. That's the single biggest reason roasting times feel unreliable.
Every time below is at 425°F with the cut size stated next to it. Change either one and the number changes, in ways this page spells out rather than leaving you to guess.
Roasting Times at 425°F
| Vegetable | Cut | Time | Doneness cue |
|---|---|---|---|
| Beets | ¾" cubes | 35-45 min | Knife slides in with no resistance |
| Potatoes | ¾" cubes | 30-40 min | Golden crust, fluffy inside |
| Sweet potatoes | ¾" cubes | 25-35 min | Caramelized edges, soft centre |
| Carrots | ½" slices | 25-35 min | Browned edges, tender but not mushy |
| Parsnips | ½" slices | 25-35 min | Deep gold, sweet smell |
| Butternut squash | ¾" cubes | 25-35 min | Edges darkened, fork-tender |
| Onions | Wedges | 25-30 min | Translucent with charred tips |
| Brussels sprouts | Halved | 20-30 min | Cut face deeply browned |
| Cabbage | Wedges | 20-30 min | Frilled edges browned, core tender |
| Eggplant | ¾" cubes | 20-25 min | Collapsed and golden, not spongy |
| Cauliflower | Florets | 20-25 min | Brown patches on the flat sides |
| Broccoli | Florets | 18-25 min | Crisp browned tips, stems tender |
| Bell peppers | Strips | 15-20 min | Softened with blistered spots |
| Zucchini | ½" rounds | 15-20 min | Golden faces, still holding shape |
| Mushrooms | Halved | 15-20 min | Shrunk, browned, liquid gone |
| Cherry tomatoes | Whole | 15-20 min | Skins split and beginning to collapse |
| Green beans | Whole | 12-18 min | Blistered, still with some snap |
| Asparagus | Whole spears | 10-15 min | Tips crisp, stalks bend slightly |
| Snap peas | Whole | 10-12 min | Blistered, bright green |
| Kale | Torn leaves | 8-12 min | Crisp and papery, still green |
Kale is the exception to the 425°F basis — it burns before it crisps at that heat and does better around 350°F. Everything else on this list is happy at 425°F.
Adjusting for Your Oven Temperature
| Temperature | Adjustment | Use when |
|---|---|---|
| 400°F / 205°C | Add roughly 15-20% | Gentler browning, or sharing the oven with something delicate |
| 425°F / 220°C | Times as listed | The default that works for nearly everything |
| 450°F / 230°C | Subtract roughly 15-20% | Maximum crisping on sturdy vegetables |
| Convection | Drop 25°F, check early | Any time — moving air carries off the steam that causes sogginess |
The percentages are approximations, not conversions. Roasting isn't linear the way a boiling time is — higher heat browns the outside faster without speeding the inside up by the same proportion, so above 450°F you start burning edges before dense vegetables cook through. That's why almost every source lands on 400-450 as the usable band.
The Four Groups Worth Memorising
Twenty individual times is more than anyone retains. The useful version is four density groups, because vegetables inside a group can share a pan without any staggering at all.
| Group | Members | Time at 425°F |
|---|---|---|
| Dense roots | Beets, potatoes, sweet potatoes, carrots, parsnips, winter squash | 25-45 min |
| Cruciferous | Brussels sprouts, cauliflower, broccoli, cabbage | 18-30 min |
| Soft | Zucchini, peppers, eggplant, mushrooms, tomatoes, onions | 15-25 min |
| Thin & leafy | Asparagus, green beans, snap peas, kale | 8-18 min |
Mixing across groups is where staggering becomes necessary — covered in roasting vegetables together on one pan, and calculated for you by the vegetable roasting calculator.
Cut Size Moves Times More Than You'd Think
The times above are tied to the cuts listed beside them, and that's not a formality. Roasting speed follows the thickness of the piece, so a potato in ½-inch cubes finishes around 25 minutes while the same potato in ¾-inch cubes needs 35. Halved Brussels sprouts roast in 20-30 minutes; whole ones can take half again as long and often end up browned outside and raw at the core.
This makes cut size a tool rather than a detail. Want carrots and zucchini to finish together despite being in different groups? Slice the carrots thin and cut the zucchini into thick half-moons, and they'll land within a few minutes of each other with no staggering at all.
Roasting From Frozen
Frozen vegetables roast perfectly well, with two adjustments. Add about 10 minutes, and do not thaw them first — thawing releases water into the bag and leaves you with a wetter starting point than the frozen block. Put them on the pan straight from the freezer, spread further apart than you would fresh, and use the top of your temperature range.
The result won't crisp quite like fresh, because frozen vegetables have had their cell walls ruptured by ice crystals and hold more water. Expect good browning and a softer bite rather than the sharp edges fresh vegetables give you.
Frequently Asked Questions
How long do vegetables take to roast at 425°F?
It depends on density and cut size, not on the vegetable being a vegetable. Dense roots like potatoes and beets take 30-45 minutes in ¾-inch pieces, cruciferous vegetables like broccoli and cauliflower take 18-25 minutes as florets, soft vegetables like zucchini and peppers take 15-20 minutes, and thin ones like asparagus take 10-15.
Why do roasting charts give such different times for the same vegetable?
Because most of them don't state their oven temperature or cut size. A chart written at 450°F will list broccoli at 12 minutes while one written at 400°F lists it at 25, and both are correct for their own conditions. Always check what temperature and cut a chart assumes before trusting a number.
Do I need to flip vegetables while roasting?
One toss at the halfway point is enough for most vegetables, and stirring more often than that actually hurts browning because pieces need uninterrupted contact with the hot pan to caramelize. Vegetables roasted cut-side down for a crisp face — Brussels sprouts, cabbage wedges — are often better left alone entirely.
Can I roast vegetables from frozen?
Yes, but expect roughly 10 extra minutes and less crisping. Frozen vegetables carry surface ice that has to boil off before browning can start, so don't thaw them first — thawing makes them wetter. Put them on the pan frozen, spread them well apart, and use the higher end of your temperature range.
What is the best temperature for roasting vegetables?
425°F is the usual recommendation and works for nearly everything. Go to 450°F when you want maximum crisping on sturdy vegetables, drop to 400°F for gentler results or when roasting alongside something delicate, and use around 350°F for leafy vegetables like kale, which burn before they crisp at high heat.