We’ve had a very dry and unusual spring in Vermont, again.  While there is little we can do about the weather, there are some things you can do in the garden to be sure your plants are healthy and thriving despite what nature brings.  Mulching is a very good practice to conserve water, suppress weeds, improve the soil, and encourage natural pest control. Let’s take a closer look at the kinds of mulch materials to use, when to apply them, and how they work.

Timing in the garden is always important but often it’s our best guess about what the weather will do.  This year has been unusually dry with some heat spells followed by near frosts.  How do we deal with that?  I like to wait for mulching until mid-June so that the soil is thoroughly warmed into the root zone, 6-10 inches deep.  Mulching in May or early June will help conserve soil moisture (less watering!) and suppress weeds but slows soil warming.  This is especially important for the growing roots of transplanted tomatoes, peppers, eggplants, basil, and other warmth-loving plants.  Steady soil moisture from mulching will be especially helpful for fruiting tomatoes, cucumbers, and squashes later in the season.  

Directly seeded plants such as potatoes, onion sets, peas, carrots, spinach, kale, and lettuces will do well in cooler soils; warming soil is not good for their root growth so mulch keeps their soils cooler and moist in the summer.   If you’ve been watering your garden regularly the young plants with small root systems have appreciated your help but now is the time you can cover your soil with mulch to reduce watering needs. 

What makes the best mulch?  Nature mulches with whatever organic matter is available and that might be what is best for you.  Shredded tree leaves, lawn clippings, straw (not hay – it’s full of weed seeds!), wood chips, and mature compost are all good.  I’m not a fan of shredded exotic tree barks in bags or expensive mulches unless you have a special landscaping use.  I also can’t recommend plastic (made from petroleum) landscaping covers as they block the necessary flow of nutrients, air, and water, contribute nothing to the soil, and become a nuisance after they eventually deteriorate.  Perhaps most importantly, neither bagged tree barks or plastics are sustainable.  Newer, plant-based biodegradable “plastic” mulches are becoming available but are still a bit expensive.

My favorite general purpose vegetable garden mulch is straw.  It’s made from the stems of harvested grains like wheat & oats and contains almost no weed seeds.  While it is somewhat expensive ($8 – 12/bale) compared with local hay, it provides excellent moisture protection and weed control when tucked in around your plants at about 4-6 inches deep.  Straw is indispensable for strawberries, potatoes, garlic, and onions because of its long-term ability to block weed growth.  Straw also creates excellent habitat for beneficial spiders, toads, and newts, all valuable natural pest controllers in the garden.  One bale of straw will nicely mulch over at least 100 ft of plants.  Most local garden & hardware stores sell baled straw but often run out in mid-summer so get your season supply early. 

Other mulch materials such as lawn clippings serve a good purpose as well.  While I prefer to leave my grass clippings on the lawn to return nutrients and organic matter to the soil, it’s hard to keep up with lawn mowing in early summer. Those excess grass clippings make excellent mulch around small seedlings (lettuce, spinach, kale, flowers, etc.) after they’ve dried and turned brown.  Rake them up and add them to your garden as mulch tucked in close to the plants.

Wood chips from firewood cutters are excellent mulch where the primary need is to suppress weed growth such as in garden pathways, borders, or around perennials.  Mow down the grass/weeds and cover the ground with cardboard or multiple layers of paper shopping bags or newspapers before placing a couple inches of wood chips on top.  Once compressed this will block weed growth for the year, encourage earthworms, and enrich the soil. 

Without a doubt, a well mulched garden requires much less weeding, less watering, and looks great.  That bit of extra work now with your mulch is an excellent investment of time & effort that will pay off all summer long!

A couple of my favorite references on this topic for further reading.  Both are available in libraries & online:

Weedless Gardening by Lee Reich, Workman Publishing, pub. in 2000.

The Ruth Stout No-Work Garden Book by Ruth Stout & Richard Clemence, Rodale Press, Inc., pub. in 1972.

Seasonal Tips:

If your potatoes are up at least 6-8 inches tall now is a great time to “hill” them by pushing some extra soil in around each plant.  This encourages them to grow taller and produce more potatoes.

Keep an eye out for the early cucumber beetles on any squash or cukes.  Find them early in the morning when they are slower so you can grab them and dispatch them before they lay eggs are the next bigger generation.

Fertilize all garden plants, transplants and seedlings.  As we approach the longest days of the year, plants are growing and their nutrient needs are high now.  Organic fertilizers such as mature compost or manure, granular fertilizers, or liquid fish fertilizers are good sources of slow release nutrients that improve soil microbiology.