Between the Rows
A Guide to Vegetable Gardening

March in the Vegetable Garden

A Time for Planting

Produced by Extension Master Gardeners in partnership with 
Welcome veggie gardeners! VCE and MGNV support local gardeners with a host of resources, including free classes, plant clinics and this newsletter.

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Table of Contents:
March To-Do List | Now Is the Time | Friends of Urban Agriculture
Beating the Bugs | Organic Vegetable Garden

March To-Do List

  • Keep building healthy soil: test your garden soil and/or prep soil with compost and other amendments, as needed.
  • Before planting, make sure any plant material or debris from last season has been cleared from your growing beds.
  • Overwintering cover crops are best left in place until they start flowering, usually early May. But if you need the space or a warm spell is getting them to flower early, you can terminate them now. Learn how to do this by looking at pp. 15-17 of this four-part series on cover crops.
  • Direct sow seed outdoors: peas, beets, lettuce, arugula, spinach, kale, broccoli/raab, chard, radish, turnip, kohlrabi, carrot, potato (consider sprouting or "chitting" potatoes indoors before planting outdoors), dill and cilantro.
  • If you haven’t yet done so, plant asparagus and horseradish.
  • Harden off seedlings grown indoors, and transplant once they have at least two sets of true leaves: Brussels sprouts, broccoli, kale, early cabbage, celery and celeriac, cauliflower, leek, onions, and scallions (seedlings grown through the winter sowing method do not usually need hardening). 
  • Start from seed indoors or via the winter sowing method various warmer weather vegetables and herbs: tomatoes, peppers, eggplant, okra, corn, basil, lavender, rosemary, fennel, lemon balm, oregano, lovage, sage, sorrel, parsley, and thyme (see February's post).

  • Divide perennial herbs.
  • Cover newly planted seeds or transplants with light straw or floating row covers.
  • Build or repair raised vegetable beds.
  • Put up trellises and structures for peas and other climbing crops.
  • Monitor any season extension structures. As the weather warms, make sure you do not “cook” your vegetables, but also remember that our area can see hard freezes in March and even into April.
  • Turn your compost pile.
  • Perform tasks listed in February's post that may not have been completed.

Plant, Pest or Other Garden Questions?

Contact the Extension Master Gardener Help Desk. Even during the pandemic, knowledgeable Virginia Cooperative Extension volunteers are available to answer questions!
RSVP for March 2021 Classes

Now is the time ... to plant your cool weather garden.

It’s time to finish preparations and begin planting your spring garden. Many vegetables favor cool spring weather and allow you to start your garden early. But first, you need to examine your garden soil. It is generally recommended that soil tests be conducted every 3 years for vegetable gardens. Even without a formal soil test, it's important to prep your soil by removing any plant debris and adding organic matter and compost to your soil (see February's post for more information).

If you don't maintain compost piles at your home garden, leaf mulch, and sometimes compost, are available at county mulch centers in both Arlington County and the City of Alexandria. Other soil amendments available from most garden centers include vermiculite and coco coir (as an alternative to peat moss) among other amendments (e.g., manure, lime, gypsum). More tips for building healthy soil are available from VCE.

Timing is everything as you prepare to plant, and gardeners have many references available to guide them in their decision-making regarding when to plant some plants and whether to sow seeds directly or to start seedlings beforehand. Here are some planting guides for our area: These archived VCE/MGNV classes will be of special interest: Consider building raised growing beds to improve drainage, soil health, and plant growth. Research has shown that raising beds yields more produce than other garden methods. More information on raised beds can be found found in these publications: Intensive Gardening Methods and Water Management for Raised-bed Gardens
Arlington Friends of Urban Agriculture (FOUA).

The Plot Against Hunger Spring Garden Kickoff is a week-long event (March 13 - 20) with online and outdoor events hosted by Arlington Friends of Urban Agriculture, Virginia Cooperative Extension, Master Gardeners of Northern Virginia, Marymount University, and the Plot Against Hunger Steering Committee. While the Plot Against Hunger program may have a new home with Arlington Friends of Urban Agriculture, its dedication to local gardens and food pantries will stay the same.
Spring Garden Kickoff: Saturday, March 13 from 10:00 to 11:30 a.m.

Join us for a virtual program with remarks from Arlington County Board members, short gardening sessions, and discussions with gardeners and food pantries. We hope you’ll get inspired to garden and get involved! By registering, you’ll be eligible for a garden-lover giveaway on March 13th! 

How to Start a Vegetable Garden: Wednesday, March 17 from 7:00  to  8:00 p.m.

Not sure if you have a green thumb? Come and learn how to start a garden! Hear from experts who started their own gardens, including at a local school and church, and why they donate produce to local food pantries through the Plot Against Hunger program. By registering, you’ll be eligible for a garden-lover giveaway on March 17th!
Beating the Bugs
A monthly column on pest control in the vegetable garden by Virginia Cooperative Extension Agent Kirsten Conrad
Don't miss the online class: 
What’s Eating My [Cucumbers, Tomatoes, Eggplant, Beans, Squash]?  Insect Pest Management for the Vegetable Garden

Pests of Cool Season Plants: Lettuce, Radish, Leafy Greens
It’s March already. Thoughts turn to delicious memories of early spring delicacies from the garden, and, truth to tell, these are some of the easiest, fastest, and most pest-resistant crops to grow. But there are challenges to growing radishes, lettuce, and other leafy greens as early spring crops.  

Pest management starts with proper culture and stress avoidance right from planting. With radishes and leafy greens like spinach and kale, simply sow the seed directly on finely raked sandy loam garden soil and cover lightly to a depth of ½ inch. For lettuce, avoid covering the seeds, which need sunlight to germinate. For a spring crop, all of these early vegetables like full sun but will tolerate part shade. Soil testing in the fall allows you to have the preferred pH for your garden crops at about 6.5–7.0, and, like the rest of your garden crops, these spring plants appreciate a small amount of balanced fertilizer for healthy growth, plus a side dressing of compost as a nutrient source after 30 days.
Radishes and lettuce will mature in 30–50 days and chard, kale, and spinach in 40–70 days. Thinning is an essential task. Be sure to give radishes plenty of room by spacing them no closer than 1 inch apart in rows about 12 inches apart. Lettuce plants should be spaced 6–12 inches apart depending on the variety and will appreciate mulching to keep leaves off the soil. The spacing of chard, kale, and spinach depends on the size of the mature plant. As a general rule, space them far enough apart that the outermost leaves are touching when they are nearly ready to harvest—about 4–6 inches for spinach and mustard greens and 12–24 inches for kale and collards.

You may see problems from pests that like cool, moist conditions like slugs and snails, and you may also see overwintering harlequin bugs, flea beetles, aphids, leaf miners, and early cabbage looper larvae. Crop rotation is a great way to fool these insects, and, since all of these overwinter in the soil or on plants left in the garden in the fall, one of the best ways to prevent heavy infestations is to do fall garden cleanup and tilling. Floating row covers provide protection from insects, rabbits and deer, and late cold snaps. Consider interplanting with flowering herbs and annuals like tansy, marigold, chives, mint, thyme, nasturtium, and rosemary known to repel insects. Check out these publications for more information:  Your best bet is to keep your plants growing vigorously and attract beneficial predators that include lacewings, damsel bugs, parasitic wasps, birds, toads, spiders, ground beetles, and lady beetles.

Happy gardening!

Next Month:  Pests of the Legume Family: Beans and Peas  

Illustration © Melissa Joskow

News from the Organic Vegetable Garden

Getting Ready for March

In February the vegetable garden at Potomac Overlook was so wet and cold that we decided to delay bed preparation and work parties until March.  Some beds had patches of snow and ice or puddles of water. Many overwintered crops were frost damaged, but spinach and Red Russian kale survived, as did parsley and many cover crops. The green tops of garlic planted in a raised bed looked ready to thrive when the weather warms. (The photo to the left is of cover crops and one lone Tuscan kale plant.)

In March, our first task will be to clear the beds of weeds and the dead and diseased remains of last season’s crops.

Next we will cut down any cover crops in beds where we will plant our spring crops and spread these cuttings over the bed to dry for a week or so when they will be easier to fork into the soil before planting seeds.  In addition to enriching the soil by incorporating cover crops, we may also amend the soil as necessary at the time of planting with compost and any natural fertilizers (such as alfalfa meal or soy meal) which may be needed for a specific crop.

Before disturbing the soil, we will check to see whether it is dry enough to prevent compaction  If the soil stays together when squeezed in the hand, it is too wet to work.  If the soil crumbles, it is ready to be prepared for planting. We consider the soil temperature and the temperature needed for seed germination before planting. The earliest crops we plant are peas, radishes, and spinach. They require a minimum soil temperature of 40 to 45 degrees to germinate successfully.  They should be planted as early as conditions permit so that they can provide a meaningful harvest before their season ends in the heat of June.

Order seeds as soon as possible if you do not already have them.  Even in January we found some seed varieties already sold out. We will plant snap peas such as Sugar Snap or Sugar Ann rather than shelling peas, which have been unproductive in the heat of June.   In our experience, French Breakfast and Cherry Belle have been the most reliable radish varieties, forming plump, sweet roots in time for harvest before flowering turns them sharp and woody. 

We will plant onion sets, as early as conditions permit.   They have proven to be very productive in providing a steady supply of green onions of increasing size over an extended period.

Later in March, when the soil warms to about 50 degrees, we will sow seeds for beets, carrots, swiss chard and kale.  This year, we will plant Detroit Dark Red, an old reliable beet variety, as well as Boldor, a bright golden beet; Chioggia, a pink and white variety and Zeppo, a round red beet.  We will plant several varieties of orange carrots, as well as a yellow one. Our Swiss chard plantings will include Bright Lights, a colorful mix of red, pink, orange, yellow, and purple leaves and stems, a dependable favorite.  We will also plant a mix of red and green baby kales for spring harvest before the insects arrive that plague cole crops in the summer.

Before the end of the March we will also try to plant lettuces and arugula. This year, we have a colorful variety of lettuce mixes, as well as Black-Seeded Simpson, a favorite old reliable green leaf lettuce. March is also the time we start seeds indoors for the peppers and tomatoes that will not be transplanted into the garden until May.  Peppers should be started about 8 to 10 weeks before they are planted outside. Tomatoes should be started 6 to 8 weeks before planting.  In Virginia, March is a busy month for the gardener!

Stop by and visit the Organic Vegetable Garden at Potomac Overlook Park
2845 North Marcey Road, Arlington, VA  22207
RSVP for VCE Public Education Classes
Send us your gardening questions!
For more information on Vegetable Gardening, check out Select On-Line References for Kitchen Gardening on the Master Gardener of Northern Virginia (MGNV) site. MGNV volunteers support the work of Virginia Cooperative Extension's public education outreach.
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Master Gardeners of Northern Virginia
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