Question
I have large areas of plants and shrubs. Over the years I have used a mulch which has been treated with iron oxide. This year I used a cedar mulch. But the cost of mulching each year and the amount of work required to mulch large areas, is not winning the war against excessive weeds. My question is this: is it desirable to spread a layer of mulch (of any variety) over the leaves that have fallen  in the garden areas. It seems to make sense to me. The leaves would act as a barrier to weed germination and the layer of mulch over the leaves would add beauty. Would you recommend that strategy.
Thanks for volunteering.

Answer
There are 2 keys to successful mulching: (1) the right material, and (2) the right thickness.

Weeds generally cannot germinate without light.  I am wondering, since you indicate this is a chore you do each year, if there is a possibility that you are turning the soil or otherwise providing these seeds the light they crave.  Add moisture and soil and mulching becomes just another day at the office for them.  Remember, Weeds can lie dormant for -- no kidding here -- thousands of years.

What you need under your mulch is a good landscape cloth.  Then leave it alone.  Nothing will grow unless it's planted -- by YOU.  The barrier blocks ALL growth.  This is a weapon that NEVER loses its battle against the wicked Weed.

Landscape cloth in huge quantities will break the bank. In that case, thick layers of yesterday's newspaper (without the colored sections, which can contain heavy metal based dyes) are a highly effective Plan B. Cover with a thick layer of Cedar mulch, and you're done.

A blanket of Cedar mulch 2 to 3 inches deep is plenty for Weed control.  It will weight down the Weed barrier, and it looks beautiful.  Because it's Cedar, it lasts.

Cedar owes its durability almost entirely to toxic 'Terpenes'. Dr Linda Chalker-Scott, Washington State University horticulturist, notes that one Cedar species used for mulching products, Thuja plicata, produces Thujaplicin, a chemical that damages Bacteria and Fungi. 'This antimicrobial activity is probably responsible for the rot-resistant nature of Cedar Wood,' she says.  You can read her study here:

www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/Myths/Allelopathic%20wood%20chips.pdf

Cedar ranks with Hardwoods, Pine and Cypress as the Big Four most popular mulches on the market. REAL Cedar also bothers a long list of insect pests -- Chinchbugs, Pillbugs, Ants, Fleas, Termites and others.

Just make sure you're using REAL Cedar mulch. That's not as easy as it sounds.  Red Cedar -- Juniperus virginiana -- isn't Cedar.  It's Juniper.

Compost the leaves, or shred them and mix in with your favorite perennials.  They're too good to waste.

THE LONG ISLAND GARDENER