Fruits and vegetables don't mix in the refrigerator bin, that is.

"There's more consumers can do to prolong the life of the fruit and vegetable than throw them into the crisper," said Don Middaugh, produce marketing manager of Shamrock Foods Co.If you've made untold trips to the supermarket to replace that moldy onion or soft potato, you already know the frustration of improper storage.

Middaugh, who teaches seminars on proper handling of produce, says knowing how to treat the produce once you take it home can increase its life and save you time and money.

Never store fruits and vegetables in the same drawer. Fruits produce ethylene gas, which triggers the ripening process. When you combine fruits and vegetables, the gas from the fruit deteriorates the vegetable.

Fruits' ripening time can be controlled by controlling the gas. Warm temperatures stimulate ripening; cold temperatures inhibit it. Thus, unripe fruits should ripen at room temperature; ripe fruit should be refrigerated.

To speed up ripening, put unripe fruit in a paper bag to concentrate the gas. If the fruit is really hard, add a piece of already ripe fruit. The gas from it will stimulate the gas of the other. An avocado will ripen in two days in a sack, says Middaugh. Add a piece of kiwi or a banana and it will ripen in one.

Tomatoes should always ripen at room temperature because of their cell structure and delicate nature. Cold temperatures trap the gas in tomatoes, causing them to turn mushy, Mid-daugh said. The half-ripe tomato at room temperature will emit the gas, stay firm and turn bright red. The warmer it is, the faster it will ripen. Once ripe, slice, dice or chop and put in the refrigerator for no more than 30 hours in a covered container. But remember, refrigeration will render it flavorless.

When you wash any vegetable, make sure to drain it well to prevent water in the bin, which will deteriorate the produce.

Here are some of Middaugh's storage suggestions.

- CELERY. Cut 1/8-inch off end and top and immerse celery in 100-degree water for 15 minutes. Drain for 10 minutes and put in an airtight crisper. It will stay crisp for four weeks.

- LEAFY VEGETABLES. Romaine, green leaf, red leaf and Bibb or Boston lettuces. These lettuces expire quickly because they are 85 percent to 90 percent water, much of which they lose in transit from the field to the store.

To preserve the lettuce, says Middaugh, "send it into shock." Take the product and cut off about 1/8-inch of the stem end; the leaves should still be attached.

Plunge into 95 to 100 degree water for three to five minutes. (Three-and-a-half minutes is ideal, five minutes is the maximum to avoid blanching.)

Drain with the stem up, 10 minutes, and put it into a vegetable crisper. Don't dry the leaves. In an hour, the lettuce will go into shock and will stay crisp for 9 to 14 days, depending on the temperature of your refrigerator.

- HEAD OR ICEBERG LETTUCE. Because it's more porous than any other type of lettuce, rap the core end on the counter and twist out the core, turn upside down and let cold water from the faucet fill the cavity. When the cavity is full, turn the lettuce over and let drain for 15 minutes. Put the lettuce in the crisper in the refrigerator, where it should last for two weeks with little or no decay.

- CUCUMBERS AND BELL PEPPERS. These get soft on the ends, shrivel and mold if there's any humidity. Store them in airtight containers or in the refrigerator drawer at a temperature no less than 45 degrees. Bell peppers and cucumbers from home gardens should be lightly oiled with vegetable oil and placed in a crisper.

- STRAWBERRIES. Never wash a strawberry or cut off the end cap until ready to serve or it will rot from the inside out. Store strawberries in the basket, not an airtight container. Check the basket and throw out any bad strawberries because they will decay the rest. If they are dry and cold, they'll last three to four days.

- ONIONS. Leave onions out of the refrigerator until you use them. The moisture in the refrigerator makes onions mushy and moldy. Once sliced, cover with plastic wrap and store in the drawer. They will last three to five days.

- SQUASH. Put in the vegetable crisper. Don't wash. When using half a squash, cut the end opposite the stem first to avoid quick decay.

- BROCCOLI. Cut an inch off the stem, stand the broccoli in 100 degree water for 15 minutes, take it out and put in a crisper. Because broccoli drinks from the stem end, the florets that break off - or bought separately from the stem - cannot be revived. If you break off the florets, put them in a crisper and cover with ice. Pour off the excess water daily and the florets will stay crisp and dark green for seven to nine days.

- BANANAS. To keep a ripe banana at the peak of ripeness for an extra three days, put it in a non-transparent plastic bag (like a garbage bag), seal with a twist tie and put in the refrigerator.

Left on the counter, bananas should last two days once ripe. In the refrigerator, they'll hold four to five days.

- POTATOES. Buy small amounts and store in the dark. A temperature of 55 degrees is ideal for maximum quality.