But you should blanket your garden beds at least twice a year — in early spring and late fall — to retain moisture and keep down weeds. That’s why it’s so important to learn how to mulch correctly.

How much is enough?

If you’re a numbers geek, try this method:

To determine how much mulch you’ll need, multiply the length and width of your garden space (in feet) by the mulch height (about 3 inches, or a quarter of a foot) to get total cubic feet.

Bagged mulch is sold by the cubic foot. To figure the number of bags, divide total cubic feet by the number of cubic feet in each bag.

Bulk mulch is sold by the yard. To figure the number of yards, divide the total cubic feet by
27 (there are 27 cubic feet to 1 cubic yard).

If all that makes you want to pull out your hair, just use one of these easy mulch calculators:

• Gardenplace.com features a calculator that tells you how many bags or trucks of mulch you’ll need.
• Colorbiotics Mulch Tool (iPhone, iPad: free): Not only calculates how many cubic yards or bags of mulch you need, it also helps you pick the mulch color that looks best around your house.
• Material Calculator (Droid: \$1.99): Calculates how much mulch — and sand, gravel, stone dust, topsoil — you need, and converts from English to metric units.

Bags or bulk?

It depends on what’s more valuable to you — time or money.

If you want to save money, then bulk is the way to go. In Virginia, for instance, shredded hardwood mulch in bags costs about \$50/cubic yard; bulk is \$30/cubic yard — about a 40% savings.

Also, delivering bulk mulch, where trucks just dump and run, is about 25% less expensive than delivering bags, which someone has to drag and stack.

If you want to save time, mulch by the bag is for you.

• Bags are easy to carry to and spread on garden beds. Just rip and dump.
• Extra bags are easily stacked and stored.
• You don’t have to sweep up after a bag delivery; you will after a bulk delivery.