Summer vegetables finish their season.

Cooler temperatures come.

This ends their growing time.

If frost comes before the last tomatoes turn red, a gardener can put a thin cloth over their cages.

This keeps them warm.

These white sheets are called row covers.

People use them in two ways.

They can float over plants.

Or people can attach them to hoops in the ground.

The hoop method protects weak stems and leaves better.

The hoops stop the cloth from crushing the plant.

Row covers also protect cool-weather vegetables.

These include spinach, radishes, cucumbers, potatoes, kale and lettuces.

The sheets block UV light.

They cannot do miracles.

But they can raise the temperature around plants by up to 8 degrees F.

That can mean life or death.

Row covers come in many sizes.

People can cut them to fit.

They are sold in three weight grades.

Light materials give only a few degrees of protection.

So people mainly use them as bug barriers in spring.

They let about 90% of sunlight reach plants.

Heavy fabrics give the most warmth.

But they block sunlight and water a lot.

They can make the temperature too high.

Medium fabrics balance the two.

They let 70% to 85% of sunlight through.

They warm the air by 4-6 degrees F.

This can give several more weeks of growing time.

Floating covers should lie loose over low plants.

People secure them by burying the edges.

Or they put stones or bricks around the edge.

Leave enough room for plants to grow.

For taller or weaker crops, gardeners can buy ready-made hoops.

Or they can bend soft PVC pipes into U shapes.

Then they push the ends into the soil.

Covers can go over one plant, a whole row or a raised bed.

Plants still need care.

Check the soil water.

Remove covers when flowering plants need pollination.

Pull covers back on warm days.

This stops the vegetables from cooking before harvest.