When summer vegetables finish their season, cooler temperatures come.

This means their growing time is over.

Sometimes frost comes before the last tomatoes turn red.

Then a gardener can put a thin fabric sheet over their cages.

This keeps the plants warm.

These white sheets are called row covers.

You can use them in two ways.

You can let them float over the plants.

Or you can attach them to hoops in the ground.

The hoop method protects weak stems and leaves better.

The hoops stop the fabric from crushing the plant parts.

Row covers also protect cool-season vegetables.

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

They help when colder weather comes.

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 the difference between life and death.

Row covers come in different sizes.

You can cut them to fit.

They are sold in three weight grades.

Light materials give only a little protection.

They raise the temperature by a couple of degrees.

So people mostly use them in spring to stop insects.

They let about 90% of sunlight reach the plants.

Heavy fabrics give the most warmth.

But they block a lot of sunlight and water.

They can also make the temperature too high.

Medium fabrics are in between.

They let 70% to 85% of sunlight through.

They warm the air by 4-6 degrees F.

This can give several extra weeks of growing time.

You should put floating covers loosely over low plants.

Then secure them by burying the edges.

You can also put stones or bricks around the edge.

Leave enough space for the plants to grow.

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

Or they can bend soft PVC pipes into upside-down 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 moisture.

Take off covers when flowering plants need pollination.

Pull covers back on warm days.

This stops the vegetables from getting too hot before harvest.