Ready, Set, Adapt! Climate Change: 2018 Notes from the Field

Part 3: 2018 Notes from the Field

Organic VegetablesMaster Gardeners of Northern Virginia manage the Organic Vegetable Garden at Potomac Overlook Park in Arlington. Each year, this demonstration garden produces hundreds of pounds of produce which it donates to the Arlington Food Assistance Center. The following Notes from the Field, compiled by Judy Johnson and Judy Salveson, highlight some of the challenges the garden faced in 2018 due to record-breaking weather.

  • In late February, we found some spinach, kale, tatsoi, cilantro and arugula had survived the winter.
  • Because the weather was so cold and wet in March, seeds for most cool weather spring crops were put in later than usual and did not have enough time to get established before hot weather hindered their growth and quality. Peas were not successful.

  • Turnips, beets, and carrots put in early were successful and achieved harvestable sizes before the weather got too hot. Onion seedlings and sets were fast growing and an excellent crop.

    Spring crops in May 2018 at the Organic Vegetable Garden. Photo © 2018 Judy Salveson

    Spring crops in May 2018 at the Organic Vegetable Garden.
    Photo © 2018 Judy Salveson

  • Tomatoes and beans did not set when both daytime and nighttime temperatures were high.
  • The heavy rains leached nutrients from the soil. Beds tested low for potassium. Nitrogen may have been low as well. This is a hunch as Virginia Tech does not test soil for nitrogen.
  • Some crops suffered from more fungal diseases as a result of the constant dampness of the soil. Rust appeared earlier on some beans. Phytopthera appeared in the sweet pepper beds late in the season. Mite damage was aggravated by dampness and heat reduced sweet pepper production.

Mite damage on green peppers at the Organic Vegetable Garden. Photo © 2018 Judy Salveson

Mite damage on green peppers at the Organic Vegetable Garden.
Photo © 2018 Judy Salveson

  • Hot peppers thrived all summer, remaining productive until a killing frost in November.
  • Some garlic varieties produced multiple shoots and small heads rather than a single large head because of the alternating warm and cold weather throughout the winter.

Number of Warm Nights Predicted to Increase 

The type of changes chronicled by the Extension Master Gardeners at the Organic Vegetable Garden will continue as climate change impacts our region. One of the many such changes is the increase in warm nights.

The maps below show the projected number of warm nights (temperatures above 75°F) per year in the Southeast under lower and higher emissions scenarios for the mid- and late 21st century. In plants, increases in the number of warm nighttime air temperatures can affect respiration, pod set, pollen viability, plant growth and crop yields.

Plant Hardiness Zone Figure Description:  Number of Warm Nights Figure Description -   Figure 19.5: The maps show the projected number of warm nights (days with minimum temperatures above 75°F) per year in the Southeast for the mid-21st century (left; 2036–2065) and the late 21st century (right; 2070–2099) under a higher scenario (RCP8.5; top row) and a lower scenario (RCP4.5; bottom row). These warm nights currently occur only a few times per year across most of the region (Figure 19.4) but are expected to become common events across much of the Southeast under a higher scenario. Increases in the number of warm nights adversely affect agriculture and reduce the ability of some people to recover from high daytime temperatures. With more heat waves expected, there will likely be a higher risk for more heat-related illness and deaths. Sources: NOAA NCEI and CICS-NC.

Sources NOAA, NCEI, and CICS-NC,

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