7 Household Trash Items You Should Save in Fall to Protect Plants From Frost

Frost warnings in October can seem to arrive with barely a day's notice. One evening, the forecast dips toward freezing while the peppers are still loaded and the fall lettuce is finally filling out. Good frost protection on a night like that doesn't have to come from a garden center.

Before buying frost cloth, take a look in the recycling bin. Last week's delivery boxes, milk jugs, and newspapers can protect plants from frost for a night or two, and the old bedsheet in the linen closet will cover a whole bed of peppers.

There's a limit to what cardboard and cotton can do. They'll carry plants through a light frost, the kind that whitens the lawn at dawn and is gone by mid-morning, but not a freeze that sits in for days. First frosts are often followed by weeks of mild weather, though, and getting tender crops past that one night can stretch the harvest.

Why DIY Frost Protection Works

So why does a thin bedsheet make any difference? On a clear, calm night, the soil gives off the heat it soaked up during the day, and with no clouds overhead, that warmth drifts up and away. Covers catch some of it on the way out. Drape yours loosely so the edges reach the ground, and the stems have some air space – Home Depot sells steel grow tunnel hoops with a row cover for lifting fabric over a whole garden bed.

Once the air warms above freezing in the morning, the covers need to come off, or they'll trap heat and moisture around the plant. Plastic is the riskiest material here. Wherever it presses against leaves, it carries the cold straight through, so it belongs on a frame or over a fabric layer, never directly on foliage. An analog outdoor thermometer, like this one from Walmart, hung near the garden, makes the morning check easier, though air at ground level can run a few degrees colder on still nights.

7 Household Items to Save

Stash these as they come through the house, and keep them dry until a frost advisory goes out.

1. Cardboard Boxes

Flip a box over the plant at dusk. If the cardboard presses on the tips of a young shrub or pepper plant, go up a size and fold the flaps inward so the edges rest on the soil. Container herbs can go under one too. Set a brick on top if there's any wind in the forecast, since an empty box weighs next to nothing. Cardboard also blocks every bit of light and turns soft in heavy dew. It needs to come off first thing in the morning.

2. Old Bed Sheets and Pillowcases

A queen-size flat sheet will stretch over a good length of border. Save pillowcases for the odd small plant. By morning, a cotton sheet is often heavy with dew, and stakes or tomato cages pushed into the bed first keep that weight off tender stems. Rocks along the hem will hold it, or you can snap a few row cover clamps from Home Depot onto the stakes. A tarp over the top helps on rainy nights, as long as none of that plastic touches leaves.

3. Plastic Milk Jugs

Cut the bottom off a gallon (3.8L) milk jug, and it becomes a mini cloche for a seedling or a young head of lettuce. That's the same idea behind the reusable plastic cloche from Walmart, though a rinsed jug costs nothing. Press the open edge an inch or so (2.5cm) into the soil to keep it from blowing over, and leave the cap on for cold nights. Twist the cap off on sunny days to let heat escape – a sealed jug in full sun warms up fast.

4. Bubble Wrap

On a frosty night, the roots in a patio pot sit only a pot wall away from the cold air, while roots in the ground have soil all around them. Bubble wrap taped around the outside of the pot, below the rim, gives them a layer of trapped air to slow heat loss. Since the wrap never touches the plant, it can stay on through a stretch of cold weather, and pots pushed together against a sheltered wall hold their warmth a little better.

If you can't save up enough bubble wrap for your plants, then it's worth picking up a roll of Amazon Basics bubble wrap.

5. Newspaper

If there's newspaper around the house, spread a few sections several layers thick over low, tender plants and young vegetables, or roll one sheet into a cone for a single seedling. Weigh the corners with rocks or a scoop of soil. Once the dew soaks in, paper loses much of its insulating value. Take it off in the morning and let it dry. On wetter nights, a polypropylene frost blanket, like this one from Home Depot, holds up better.

6. Autumn Leaves

Rake the leaves into a pile and leave them there for now. Once the soil has cooled in late fall, a few inches heaped around a tender perennial will insulate its crown and roots, though they won't help the foliage. Spread too early, and a leaf layer keeps the ground warm and can give voles a spot to settle in. Shred the leaves with a mower first or a leaf mulcher, like this Worx one from Amazon – the pieces stay loose and drain well – and leave a small gap around each stem so the crown doesn't sit wet all winter.

7. Toilet Paper or Paper Towel Tubes

Slide a whole toilet paper tube, or a third of a paper towel tube, over a seedling or young transplant and push it about an inch (2.5cm) into the soil. That little collar stops cutworms such as the black cutworm (Agrotis ipsilon) from chewing through the stem at the soil line, and it takes some of the bite out of a cold wind, too. Tubes won't do much against frost by themselves, though, so pair them with a milk jug or newspaper on cold nights.

Boxes in the garage and old sheets in the closet can carry a garden through those first chilly nights. Pull the covers each morning, fold them up, and they'll be ready the next time the forecast drops. With a little luck, a few more peppers will ripen before the season wraps up.