We've all pulled open the vegetable crisper to discover yet another yellowing broccoli, flowering rapini or liquefying cucumber, only to beat ourselves up on the walk of shame to the green bin. But there are those times when we're not quite sure if a fruit or veggie is salvageable or destined for compost. When in doubt, turn to these handy guidelines.

Yellowing broccoli
If it's just yellowed here and there, trim it off and give it a sniff. If it smells only of broccoli, then it's still good to use, but not raw. Peel the stalk and cut away any soft or discoloured parts. If it's yellow in more places than green, going black and slimy in spots or smells like stale water from an old vase of flowers, toss it!

Brown spots on cauliflower
If the head is firm and brown spots are light in colour and not too numerous, just shave or slice them off and cook the cauliflower. If the head is rubbery, it will likely smell funky and should be tossed.

Leafy greens
Kale, collards and chard are prone to drying out and wilting in the fridge. If your greens have gone limp, try rehydrating them in a sink of ice-cold water. If your greens are yellowing, toss 'em.

Herbs
Since herbs are most often minced very finely, you can get away with wilting due to dehydration, but if there's mould, browning or blackening, toss 'em.

Onions and garlic
A sprouting onion or bulb of garlic is best for planting in the garden. The sprouting turns the flesh bitter and mushy. Either plant them or toss 'em.

Potatoes
Spuds left for a while can begin to sprout or develop "eyes." No need to toss them; just scrub or cut off the sprouts and eyes. Also, cut off all green parts of the potato; it's true that green spots are poisonous to humans! If your potatoes are getting wrinkly and soft, turn them into soup. But if they're soft, liquid-y or have black spots, toss 'em. And we guarantee, if you've ever smelled bad potatoes, you'll never forget it.

Photography, iStockphoto.com.