Beginner's Guide to Growing Food in DC

Organically grown, local food is in the news and sure enough, many of us are looking for help in growing food for the first time.  So at our urging, Christa Carignan, author of Calendula and Concrete, has compiled this amazing guide for us.  Please give us your comments and additions in a comment below, and we'll incorporate them in the guide before it goes on our site.  [Seriously, thanks, Christa!]

I want to grow a vegetable garden. How do I start?

• For the best results, choose a location that gets at least 6 - 8 hours of direct sunlight each day. Make sure a water source is readily accessible. (Do you have a faucet nearby? Can you install a rain barrel on site?). Also, make sure your site has good drainage.

• Don't have a sunny location? "Leafy greens—bok choy, kale, spinach, mustard greens, leeks, and Swiss chard—grow well in shady environments, as do broccoli, turnips, rutabagas, zucchini, and cabbage..." (Hope Reeves, New York). "Shade-loving plants with shallow root systems—like radishes, beets, and lettuce—can be grown in containers smaller than ten inches in diameter", according to Sonia Uyterhoeven of the New York Botanical Garden.

• If you have limited space, consider growing a garden in containers. "Anyone who has a window or a fire escape, some terra cotta or wooden containers, and a bag of soil can grow a multitude of fruits and veggies." (Hope Reeves, New York, September 2007). Some seed companies sell "miniature" varieties of vegetables that are well-suited for containers (e.g., Thumbelina carrots, Spacemaster cucumbers). Make sure the containers are suitable in size for what you want to grow (tomatoes and peppers are deep-rooted vegetables). The container should have holes for drainage/air circulation. Water your plants regularly -- container gardens dry out much faster than gardens in the ground. Some places sell "self-watering" containers. Maryland Cooperative Extension has a free fact sheet on "Container Vegetable Gardening.".

• Join a community garden. There are about 30 community gardens in the District of Columbia alone. The American Community Gardening Association has a database of community gardens elsewhere.

Test your soil

The most important step to growing healthy vegetables is providing healthy soil. Make this a priority in your first year of gardening.

• From a DC Master Gardener: "Even if the only thing you accomplish in your first year of gardening is building a great soil, you will be ahead of the game and richly rewarded later. Before planting anything, have your soil tested by a reputable soil laboratory. Do not try to do this yourself with one of the amateur kits sold at garden centers. You need a thorough assay of the structure and nutrients in your soil, as well as any hazardous materials. Urban gardeners should be concerned about the potential for heavy metals or other toxins in their soil, especially lead and arsenic. Lead in soil is almost a universal condition in urban areas, especially near older buildings that might have shed lead paint and near heavily trafficked roadways, where lead in automobile exhaust has drifted into yards. Purchasing soil for a new garden or raised beds is no guarantee that it is pure. The potential danger of lead being taken up by vegetables is highest in leafy greens and root vegetables. Lead does not appear to be a problem in fruits or fruiting vegetables."

• From another DC gardener: "By far the most dangerous aspect of soils with high lead levels is airborne contamination, inhalation, oral ingestion from hands touching lead-laden plants, clothes, shoes, etc." Lead is very stable and therefore difficult to remove from soil. Brassica plants (e.g., broccoli, cauliflower, cabbage, brussels sprouts) tend to take up more lead than others, so brassicas (and all root crops) might not be the best choice in soils with lead. "I recommend the University of Massachusetts soil testing lab." It's inexpensive and you can get information and recommendations on soil fertility, pH, toxins, etc. In soils with high lead levels, take precaution and do not plant directly into the soil. Use raised beds (high enough to keep roots away from lead-laden soil). To create a good soil mixture inexpensively, use the "lasagna gardening" method (described in more detail below).

• Another DC gardener adds: "There is no agreed-upon definition of top soil and no standards. Even within a brand, unlike with potting soil, there's no standard or consistency. The last time I looked at the ingredients of top soil at Home Depot and Lowe's, fly ash was one of the main ingredients. I'd never want to grow vegetables in that (probably contains lots of heavy metals). I grow vegetables in raised beds with pure compost made by me. But I still get my soil tested (but not the compost)."

• If you have concerns about lead in your soil, make sure to thoroughly wash and peel root vegetables before eating.

• Not all soil labs test for lead. Check with the lab before sending in your sample. The Maryland Cooperative Extension has a list of regional soil test labs on its website.

• A basic soil test will also help you determine the soil's pH and nutrient levels. Soil pH governs the uptake of nutrients by plants. Vegetables grow best in soil that has a pH between 6.0 to 7.5 (around 6.8 is ideal).

• From a DC Master Gardener: "Plants need certain macro-nutrients to thrive, especially nitrogen, potassium and phosphorous. A professional soil test should indicate whether your soil contains adequate levels of these nutrients. The test should also indicate the level of vital micro-nutrients, especially calcium and magnesium. Even more important is "saturation percentage" of calcium and magnesium, and the relative saturation of one to the other. The desired range is 65% to 75% for calcium and 10% to 15% for magnesium."

• Test your soil once every three years.

• Organic Gardening's website has a good section on Understanding Soil.

How to I prepare my location for planting?

• Remove stones, grass, weeds. Check the consistency of your soil. A squeezed handful of soil shouldn't clump (too much clay) or crumble (too sandy). Vegetables grow best in soil that's rich in organic matter (a minimum of 5%). You can improve soil by adding compost, aged manure, and other amendments such as lime, bone meal, etc., (based on the results and recommendations of the soil test). Bags of compost can be purchased at garden centers and nurseries, but that gets expensive quickly. Some places offer compost in bulk; you can buy it by the truckload. In Maryland, Pogo Organics offers this service. To save money, build a compost pile of your own. Read the DC Urban Gardeners primer on Composting.  Montgomery County Maryland residents can get a free basic compost bin from the Department of Environmental Protection. If you don't have a yard our outdoor space for a compost bin, consider setting up an indoor vermicomposting ("worm composting") system to turn your food scraps into compost. 

• Don't want to dig up sod? Try Lasagna Gardening or Sheet Composting. Lay down sheets of wet newspaper or cardboard followed by layers of other organic materials (grass clippings, leaves, soil mix, straw). These layers will eventually "smother" the existing vegetation where you want to plant.

• Build raised beds. Raised beds tend to have better drainage, and the soil warms up faster in the spring so you can plant a little sooner.

When can I plant?
The District of Columbia is in USDA Zone 7A. The average last frost is around April 15, and the first frost in the fall is usually around October 15. Based on these dates, you can make a planting schedule.

• Many gardening books provide a basic month-by-month calendar of "what to plant when." A good one is Rodale's Almanac & Pest-Control Primer.

• A good online resource for planning is the Weekend Gardener Grow Guide.

• Washington Post online has a basic month-by-month gardening calendar.

• Washington Gardener E-News also provides monthly reminders. Sign up here for the newsletter.

• Maryland Cooperative Extension has a free fact sheet, "Planting Dates for Vegetable Crops in Maryland".

• Cool season plants -- peas (sow as early as February/March), radishes, lettuces, spinach.

• Warm season plants -- tomatoes, peppers, basil, eggplant -- should only be transplanted outside after all danger of frost. Usually after Mother's Day, it's safe in our Zone 7A.

• Last season crops -- in July plant seeds of lettuce, arugula, carrots, beets, chard, kale. These do well in cool weather, and some plants overwinter in our area.

• In October - plant garlic, onions. They'll overwinter and you can harvest them next summer.

• Extend the season by creating a cold frame to protect plants from frost.

Where can I get seeds and plants?
Purchase plants at local nurseries such as American Plant Food Company and Behnke's. They're likely to have a better selection -- and healthier plants -- than big-box stores such as Home Depot. Avoid plants that are getting long and lanky or yellowish. For the best variety, and/or to save money, many vegetable gardeners prefer to start plants from seed.

• Seed Exchanges and Plant Swaps. Check out Washington Gardener magazine's annual Seed Exchange (January). Neighborhood gardening clubs also hold plant swaps occasionally (find a DC-area garden club here. Go online to exchange seeds at Garden Web or use the Garden Online's Seed Exchange. Ask your neighbors for seeds or transplants. Post a message to your local Freecycling group and see if anyone in your neighborhood has the seeds/plants you're looking for. Gardeners like to share!

• Seed Catalogs. Good ones for vegetables are Seed Savers Exchange, Seeds of Change, Baker Creek Heirloom Seeds, Fedco Seeds, Vermont Bean Seeds Company. They will send you a free catalog for the asking, or just place your order online.

• D. Landreth Seed Company has a good selection of seeds for patio gardeners. 

• America the Beautiful Fund offers grants of free seeds to community groups.

What about plant pests and diseases?
Plants are susceptible to viruses, parasites, and diseases. The following resources can help you determine what's bugging your plants, and what to do about it.

• Vegetable MD Online   

• Maryland Cooperative Extension answers plant and pest questions. Call their free hotline, Monday - Friday, 8 am - 1pm, at 1-800-342-2507. Outside of Maryland, call 1-410-531-1757.

• The Brooklyn Botanical Garden staffs a Gardener's Resource Center to vet questions. The hotline is 718-623-7270.

Final Thoughts
Start small, go easy! A single zucchini plant can provide enough zucchinis for two people for an entire summer. It's easy to plant too much at first and then become overwhelmed with the chores of watering, weeding, harvesting, soil amending, etc. Vegetable gardening takes effort, and it's extremely rewarding when you succeed. A great resource for determining how much to plant (and how) is Mel Bartholomew's Square Foot Gardening. Also, consider starting with some of the easier-to-grow plants: lettuce, Swiss chard, kale, radishes, squash, cucumbers, carrots, turnips, beans, basil, thyme.

Additional Resources

• DC's 7th Street Garden offers clinics on growing vegetables.

• Consider volunteering at the Washington Youth Garden, located in the National Arboretum. They have a large piece of land under cultivation with all kinds of different vegetables and people who can teach you the best techniques.

• The New Seed-Starters Handbook is an excellent book with information on growing garden vegetables from seed, how to set up a cold frame to extend the season, and how to save seeds from year to year.

• National Gardening Association publishes an online newsletter for urban and small space gardeners and another on how to grow edible landscaping. 

• The New York and Brooklyn Botanical Gardens offer year-round workshops on urban gardening.

• Kitchen Gardeners International has an online forum and blog for food gardeners.

Comments

[Ed Bruske]

I think we need to be more specific about the sunlight requirements for vegetables. I don't know any vegetables that like full shade. Some--lettuce, carrots--tolerate or even like partial shade. Most leafy greens like protection from the hottest sun of the afternoon. The brassicas--cabbage, mustards, bok choy, arugula--are cool weather crops. They do best when the sun is lower in the sky. But they still do better with more sun, in my experience.

A general rule is, 4 hours direct sun minimum for leafy greens, 6 hours direct sun minimum for fruiting vegetables. Is there agreement on that?

Most gardeners have no idea what a tolerable lead level is in soils, and consequently won't be able to interpret the results of their soil tests. We should tell them.

According to the USDA's Biological Waste Management and Organic Resources Laboratory in Beltsville:

"Looking at the whole data base, it would appear that crop lead is not yeat a significant limitation for growing vegetables in a garden with 500-1,000 ppm (parts per million)soil total lead (so long as crops are washed and root vegetables peeled). However this much soil lead when present in areas frequented by children can significantly contribute to blood lead in children. Gardens very high in lead (say, over 3,000 ppm) could be used to safely grow fruits and grain crops, but not leafy or root vegetables. For these very high lead gardens, extreme care would be needed to reduce soil transfer to housedust and minimize exposure of children, too much care for practical gardening."

For local planting times and specific information on how to handle different vegetables in our area I like "The Washington Star Garden Book 50th Anniversary Addition." It's available from Amazon.

I'm becoming more an more skeptical of searching all over the country for vegetable seeds. I think we've gone overboard with all the boutique varieties. We have some very good local seed purveyors. D. Landreth in Baltimore is a full-service company--the oldest seed company in the country--with lots of heirlooms. I look first to the Southern Exposure Seed Exchange outside Charlottsville--mostly heirloom varieties lovingly tended.

[Ed Bruske]

In my surveys of the literature, I have not seen a reference asserting that brassicas are more prone to taking up lead than other vegetables. Can we have a citation for this? The research results I have seen indicate that uptake of lead through plant roots is pretty slight, and would be of most concern in leafy vegetables, which could include some brassicas. In any case, I don't think we should brand any particular group of vegetables (in this case a vastly huge group) as being a particular hazard unless we can cite the research.

Here is a link to the University of Maryland Extension Service info on lead in gardens: http://www.hgic.umd.edu/_media/documents/hg18.pdf

We should also say that ALL vegetables from the garden should be thoroughly washed, especially if there is a concern about heavy metals. Root vegetables should be peeled where lead is present.

[Ed Bruske]

I erroneously listed calcium and magnesium as "micro-nutrients." They actually should be included with the macro-nutrients.

[Lara Ballard]

This is great, but I'd also like to see more encouragement and guidance for growing perennial fruits and vegetables. I'm also looking for something called "tree collards" (perennial kale). Here, incidentally, are some great resources on both perennials and annuals (books available for sale on these websites--I own them; they're great):

http://www.edibleforestgardens.com

http://www.growbiointensive.org

[Kathy J, Washington Gardener Magazine]

For part shade garden - try asparagus too.
Some herbs will tolerate part-shade as will a few edible fruit-bearing trees and shrubs.
You mostly discussed annual vegetable-growing (BTW look up the history of the word "vegetable" - it is enlightening), but an edible garden can also contain fruit trees and shrubs; berries on shrubs, vines and canes; annual, perennial and woody herbs; medicinals; edible seeds; etc. Hope your "Growing Food in DC" will expand to include those categories as well. It is a huge subject and this is a great start.
A warning on that "last average frost date of April 15" - folks, that is an AVERAGE - meaning 1/2 of our local last frosts come AFTER Tax Day -- it does not mean on 4/15 you may plant outdoors with no fear of frost-bite for your wee seedlings. I always recommend Mother's Day as a good free-and-clear to plant outdoors date. Prior to that, plant with caution and keep a close on the local weather forecasts.

[Bruce F]

You've got a lot of useful information here. I'd like to add a little more.

A few of us who live in the city of Chicago are growing heirloom vegetables on our rooftops in cheap homemade earthboxes. In response to huge environmental problems, it's a small but rewarding way to push back. Also, we think they're a great way to build connections in a fragmented social/political landscape.

Here's the Flickr link, alongside the pics is a little how-to guide with plenty of relevant links.

http://www.flickr.com/photos/7458996@N06/sets/72157603652656573/

[Ms. Krieger]

Planting lettuce in July in the Washington, DC area is, in my experience, misguided. The plants sprout but the heat makes them quite bitter almost immediately, and then they bolt. I would wait til early September to plant greens for a fall/winter garden. Mind you, this is growing plants on my northern-exposure rooftop with daily watering. I can't imagine a southern exposure working at all, except perhaps in a winter coldframe.

On the upside, the same heat that makes lettuce so difficult in DC was great for tomatoes. We had cherry tomatoes from July through October on a rooftop that gets a maximum of 6 hours of sunlight in June, and no direct sun before mid-April or after September. I've found that tomatoes do fine in bright, indirect light if the weather is warm. I put them out on April 15, right when we start getting an hour or two of sun on the roof, and by the time they stop producing in late October they've have little to no direct sun for 2 months. I am trying full-size tomatoes and peppers this year. We'll see if they can thrive in these conditions.

[Ann Marie Gibb]

I received an herb garden gift set for Mother's Day. The containers they sent to plant them in say "NOT SAFE FOR FOOD"

Could whatever reason hey say that for, leach into my herbs I would plant?