Floating row cover is one of the great inventions for the modern gardener.  It is used for spring and fall frost protection and in the summer for insect protection. It is a spun-bonded synthetic fabric which can be placed directly over the top of the plant or can be suspended as a low tunnel cover.  It comes in various weights.  Each weight provides a specific amount of frost protection and shade from the sun.  Floating row cover is self venting so you don’t need to remove or vent it during the day as is necessary with plastic covers.  Floating row cover will also let water pass through it.  Floating row cover works by allowing sun light to penetrate to warm the soil during the day and then trapping the heat of the soil next to the plants at night.  The heaviest weights of floating row cover are useful as winter mulches for fall planted spring flower beds such as pansies.  Floating row cover will last for about four years if it is cared for when it is not needed in the garden.  The most useful width that I have found is 10 foot.  This width works well to cover my Quick Hoop low tunnels.  I typically order a 500 foot roll which lasts me for a long time but shorter lengths are available. 

I have not found a good local source for large pieces of floating row cover.  I typically order mine from Johnny’s Selected Seeds or Peaceful Valley.  Both sites offer good sales in the spring and fall.   Peaceful Valley often has lower prices but the shipping cost makes the overall order more expensive than from Johnny’s Seeds.  Johnny’s Seeds website has very good tutorial information about using floating row cover. 

Listed below are the characteristics of several weights of floating row cover. 

Lightest Weight Floating Row Cover

Used for Insect Protection not Frost Protection

90% Light Transmission

.45 oz/sq yard

Agribon AG-15 is an example of this weight

Light Weight Floating Row Cover

This is the weight that I use the most often.  It is the best weight for a low tunnel placed inside a high tunnel but I use it in my outside garden as well. 

Provides Frost Protection to 28 Degrees F.  (4 degrees of protection)

85% Light Transmission

.55 oz/sq yard

Agribon AG-19 is an example of this weight

Medium Weight Floating Row Cover

This is the weight that I started out using.  If you live in an area of high or consistent  wind consider using this weight. 

Provides Frost Protection to 26 Degrees F.  (6 degrees of protection)

70% Light Transmission

.9 oz/sq yard

Agribon AG-30 is an example of this weight

Heavy Weight Garden Fabric

Provides Frost Protection to 24 Degrees F  (8 degrees of protection)

50% Light Transmission

1.5 oz/sq yard

Agribon AG-50 is an example of this weight

Not useful as long-term frost protection as not enough sun light penetrates to keep heating soil.

This weight is useful as a winter mulch

Very Heavy Weight Fabric

Used For Short Term Protection

Very Heavy Weight Garden Fabric

Provides Frost Protection to 22 Degrees F  (10 Degrees of protection

30% Light Transmission

2 oz/sq yard

Agribon AG-70 is an example of this weight

Not useful as long-term frost protection as not enough sun light penetrates to keep heating soil.

This weight is useful as a winter mulch