Charlotte Kidd, M. Ed., is a writer, professional gardener, garden designer and garden coach in Southeastern Pennsylvania. She does horticultural programs for the Pennsylvania Horticultural Society, the Philadelphia International Flower Show and Longwood Gardens. She’s a member of the Society of Environmental Journalists and the Garden Writers Association. Contact her at

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Less-Stressed Veggies = More Nutrition for Us
by Charlotte Kidd    

Being well fed and healthy helps ensure we humans are at our best. Same goes for growing choice vegetables. Stress-free vegetables are more nutritious than struggling plants.

“Vegetables grown under stressful conditions – whether it is a lack of water, lack of nutrients or being attacked by insects or diseases – are not going to be as robust or have the nutritional value as good, healthy vegetables that have all that they require to reach their genetic potential as far as yield or nutritional value,” said Dr. William J. Lamont Jr., professor in the department of horticulture at Pennsylvania State University. Lamont draws on 31-plus years of hands-on, in the field experience as a researcher and extension professional with vegetable crops.

“It’s basic botany,” explained Horticulture Educator Steven M. Bogash of the Pennsylvania State University Extension in Franklin County. “Plants take up the nutrients through the root hairs, into the xylem, through the leaves and settle them out into the fruit.”

Water and minerals move from plant roots up to plant leaves through xylem — tubular-like vessels and cells. “If you are feeding what the plant needs,” and watering it, and it’s receiving enough sunlight, “it would make sense that the nutrients (mineral content) would move through the xylem stream. The fruit would be fed better,” Bogash says.

Bogash specializes in tomatoes. For several decades, he has done soil testing and plant tissue analysis on tomato crops. He works with commercial tomato growers to help them adjust growing conditions for the best-tasting, easiest to transport tomatoes.

They do the science. They test soil and apply nutrients to the soil. They test plant (leaf) tissue for nitrogen, phosphorous, potassium, calcium, sulfur, magnesium and micronutrients. They rebalance deficiencies by supplying nutrients and watering sufficiently. They test plant tissue two weeks later. 

Philadelphia’s Blaine School Community Garden students harvest pest-free midsummer vegetables.1

In Our Vegetable Gardens

A smart veggie gardener can make the most of his or her efforts, said Dr. Wesley Kline, agriculture agent for the Rutgers University Cooperative Extension in Cumberland County, New Jersey. Choose vitamin-packed vegetables you enjoy. Grow them in the best possible conditions. Store and prepare them with nutrition in mind.

First, select vegetables you and your family like. If the veggies aren’t appealing enough to eat, you’ll definitely not benefit from their vitamins, minerals and fiber. After deciding your favorites, look at which ones have the most nutritional value. “If you like them and they’re nutritious, you have a winner!” said Kline.

Growing vegetables in the best possible conditions – with enough space, food and water – allows them to reach their prime. Conscientious gardeners can tip the odds for plant health and yield. “Do everything you can do to manage diseases and insects. That reduces stress on the plant,” urged Kline. Take advantage of resources such as state agricultural extension service staff and websites for gardening, landscaping, farming and integrated pest management.

In Kline’s decades of advising, he’s found that most problems stem from poor water management and weed control. Watering too frequently or not long enough encourages vegetable plants roots to stay near the soil surface, where they’ll quickly dry out. Shallowly-rooted weeds thrive near the soil surface as well. The best practice is to water deeply, once a week, so the roots grow downward into the moist, cool soil.

Tips for Nutrition-Packed Plants

Raised beds provide better drainage than flat ground, especially helpful for tomatoes and peppers.

Space plants far enough apart so air circulates freely. This allows the soil and plant parts to dry out. Why is that important? Most plant diseases, such as powdery and downy mildew, thrive in a moist environment.

Remove weeds pronto! Weeds cause disease problems by competing with vegetables for nutrients, water and light.

Apply plastic mulch or 1-2 inches of organic mulch, such as compost, shredded leaves or newspaper, to reduce the time and frequency of watering.

Don’t automatically apply fertilizer. Most long-used gardens are overfertilized from years of added fast-acting fertilizers, said Kline. First, test garden soil for phosphorous, potassium, calcium, magnesium and pH. A good soil-test report will note deficiencies and recommend adjustments. Compost and organic fertilizers release nutrients slowly and add microbe-rich organic matter. Commercial fertilizers pack more immediately available nutrients, but they don’t enrich the soil over time.

It is important to provide ample space between vegetable plants.2

How to Water

Mulch and deeply water new transplants to suppress weeds and keep roots and soil moist.2

Generously water the roots (not the plants’ vegetation) weekly at soil level. Roots absorb nutrients via water. Soaker hoses are great for small gardens; drip irrigation for larger gardens.

Water 1 inch per week for heavier, clay soil. Apply 1½ inches per week for sandy soil.

To measure rain and drip irrigation, put several empty tuna-fish cans on a grid in a line. See how long they take to fill. Have a soaker hose? Put cans under the soaker hose to measure water flow.

Overhead watering is the last resort – water during the day so plants are dry by nightfall. Be forewarned: Plant diseases, especially on peppers, tomatoes and fruits, can develop overnight on wet plant leaves.

Community Gardens’ Top Veggies

The Pennsylvania Horticultural Society (PHS) distributed vegetable plants in May to gardeners at 115 Philadelphia community gardens. Strawberry, kale, collards, broccoli and cabbage plants are favorites, said Lisa Mosca, PHS’s City Harvest food systems specialist.

With the public health concern about diabetes, PHS offers sweetpotato slips too. Sweetpotatoes are packed with vitamins A, C and B6, dietary fiber, potassium and iron. Studies show sweetpotatoes have a low-glycemic index. That is, they release glucose slowly, which means no diabetic sugar spikes.

Ripe peppers – red, orange and yellow – have up to twice the vitamin C content of unripe green peppers, noted Mosca. Red ripe tomatoes are full of the natural antioxidant lycopene.


1. Photo courtesy of the Pennsylvania Horticultural Society
2. Photo courtesy of Charlotte Kidd

From State-by-State Gardening September/October 2013.


Posted: 12/11/13   RSS | Print


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