Monthly Archives: April 2016

Are you damaging your vegetable garden soil?

The rototiller is a popular tool used by home gardeners to control weeds, incorporate fertilizer and lime, and loosen up the soil for planting. While valuable for some purposes, it is important to recognize that rototilling does have a dark side: Earthworms and soil microbes, important for good soil health, are damaged by it. And organic matter in the soil is broken down and lost.

Farmers have learned about the negative impacts of rototillers and other tillage tools they regularly use. Today many are adopting “reduced tillage” practices to protect their soil. Cornell Cooperative Extension agriculture staff are working with Long Island farmers to help them change these practices successfully.

Since I work with farmers and CCE agriculture staff, I understand the importance of good soil health. So I decided to implement what I learned at work in my home vegetable garden, pictured below. I am excited about how my garden soil has improved. Its organic matter has increased, there are a lot more earthworms, and the soil is very friable, which makes it easy to dig holes for transplanting.

Adding a mulch cover of shredded leaves and grass from my yard and reduced rototilling has led to healthier soil and plants in my garden. Photo by Meg McGrath.

Doing less rototilling and using a mulch of plant materials from my yard created healthier soil in my vegetable garden. Photo © Meg McGrath.

Here is what I do now to protect soil health. First, I rototill only where I am directly seeding, which is currently just peas. I used to have my husband till the whole garden each spring with our big hand rototiller. Now we use a small rototiller to prepare our rows for the peas, tilling only the soil where I plant seeds and not disturbing the walkways between these rows.

Second, I cover the vegetable garden with shredded leaves and fresh grass clippings from the rest of the yard. This provides excellent weed control, so I don’t need to use the rototiller for controlling weeds. And this free mulch is a good source of organic matter that earthworms digest and move into the soil. I have a bagging, mulching lawn mower for collecting material for this ground cover. I just rake the mulch out of the way when I plant. I use a chipper-shredder to turn last year’s dead flower stalks and ornamental grasses into straw mulch to place around the base of the vegetable plants.

Third, I use a trowel or shovel to dig holes for transplanting, depending on seedling size. Often I put homemade compost and/or a little granular fertilizer in the hole, and mix this into the soil with a scratcher. Not turning over an entire row of soil when I transplant helps preserve the soil’s organic matter and improves its water retention, which is great for soil microbes and my vegetables.

Dr. Meg McGrath is an Associate Professor at Cornell University’s Long Island Horticulture Research and Extension Center in Riverhead, New York.

Hairy Bittercress: A Mustard with Momentum!

What is that battalion of tiny white flowers appearing all over the lawn so early in the season? The one with the lacy green doily at the base, and sword-like seed pods, and the maroon cast? Gasp! It is the hairy bittercress!!! Now before you call out the weed police or haul out the weed killer, consider this: Did you know that hairy bittercress is a very important early source of pollen and nectar for bumblebees? As such it should be conserved along with (double gasp!!) dandelions.

Bittercress plant with flowers and seed pods just starting to develop. Photo by Andrew Senesac.

Bittercress plant with flowers and seed pods just starting to develop. Photo by Andrew Senesac.

Now that we have that out of the way, let’s settle down to learn a bit about hairy bittercress habits and some do’s and don’ts for dealing with an outbreak of it.  This weed grows best in damp, recently disturbed soil.  Be wary of digging it up in spring because this practice opens holes for crabgrass to emerge.  A winter or summer annual, different varieties of bittercress have different heights. A key characteristic is its basal rosette, a “doily” like circular array of leaves at the bottom of the plant. The weed will germinate in fall or winter but grows best during warm weather. It quickly invades thin turf especially where there is good soil moisture. Shade encourages its growth, and it may escape mowing by low growth. Post-emergence control for it generally includes using 2, 3, or 4-way herbicide; treatment during its basal rosette stage is best before it throws up a flower stalk and begins to produce seed.

Hairy bittercress thrives in sandy, organic soil. Wash your nursery containers rather than leaving them around with soil clinging to them—dirty containers harbor its seed, with six times more seedlings emerging from dirty containers than from those that are rinsed. Also, containers lying around tend to breed Asian tiger mosquitoes! Now you have two good reasons to clean up your containers.

Hairy bittercress has exploding seed pods but little germination of fresh seed. Instead, its seed ripens with high temperatures. The higher the temperature, the greater the temperature range at which subsequent growth will take place. Hairy bittercress can germinate from April through November; however, autumn is its main period of emergence. Peak flush of germination is in November and December, but this varies from year to year. We don’t notice these plants until spring when they throw up flowers and seedheads, seeming to mock us from our winter-bound vantage points as we eyeball our winter weary lawns. Just remember: Each hairy bittercress you allow to flower helps support our vital pollinators when they really need the nectar and pollen these plants provide. So help out a bumblebee, and leave hairy bittercress alone if you can; it’s an annual so it’s gonna die anyway….

Dr. Tamson Yeh is CCE Suffolk Turf Use and Land Management Specialist. She can be reached at tsy3@cornell.edu or 631-727-7850 x240.