Although spring has not officially sprung, it feels like it here on the farm. We started planting tomatoes and lettuce in mid-January and planting hits full stride this week with cabbage, broccoli, carrots, cauliflower, kale, arugula, radishes, Hakarei turnips, onions (purple, yellow and bunching), kohlrabi, and Swiss chard. Each week we will be adding new vegetables to the list as the weather continues to warm. Of these, Lettuce has become one of our most popular vegetables.
We have spent a great deal of time researching the best varieties for taste, texture and season. Years ago, we heard that here in Missouri that you couldn’t grow lettuce in the dead of winter without a heated greenhouse; nor, could you grow lettuce in the summer without it tasting bitter. Both statements were untrue. It is all about the variety you choose for the specific season. Here are some facts about our lettuce, as you consider what is best for your table.
Variety We love to mix our lettuces for both texture and taste. We will almost always have a mix of romaine, loose-leaf and butterhead. Each one compliments the overall taste, color, and body to the salad. Additionally, it is easy to pull the assorted leaves out of the mix for burgers or sandwiches. We have three different mixes that we produce. Our winter-spring mix is listed below:
Winter Density – A dark green romaine with an upright growth habit that builds an 8-inch tall, densely packed, compact romaine head. This is my favorite of the winter lettuce variety.
North Pole – Sweet, compact, light green butterhead, which can be grown throughout winter and early spring. While quite cold hardy, it tends to bolt quickly, so can’t be grown late spring and summer.
Winter Brown – This lettuce forms smaller loose green leaves with a brown overlay. It is very robust and suited for harsh winter conditions. It gives body to the salad with its slight savoy leaf type. Thomas Jefferson liked it so much; he planted it twenty-seven times in his winter garden at Monticello.
Winterwunder – A loose-leaf variety with large 9-11 inch light green heads. It has a softer leaf that retains more water than most winter varieties.
We think you will be happy with this mix, but it will be for a limited time due to the warming weather. We expect to have it available by mid to late March and into early April. At that time, we will switch to our mid-season varieties.
Did You Know?
High levels of nitrates – should you be concerned?
High levels of nitrates, which are a cancer causing agent, can be found in some vegetables. Lettuce, if not harvested or grown properly, can contain a high level of nitrates.
Keys to reducing nitrate levels:
Time of Harvest – We harvest all of our lettuce in the afternoon. Since nitrate concentrations build during the night and decrease during the sunny part of the day. Experiments at the New Alchemy Institute showed a 15 to 20% decrease in nitrate levels in lettuce harvested in the afternoon compared with those harvested in the morning.
Compost Made on the Farm - The rate, form and timing of fertilizer applications all influence the uptake of nitrate by crops. We use compost made right here on our farm in our soil mixes, but anyone using a soluble N source—including some quick-release organic fertilizers—should be warned. This can contribute to high levels of nitrates in the vegetables.
Light Exposure – The more light the better. This is why nitrate levels are highest in the late fall and winter months. When the New Alchemy Institute exposed spinach and lettuce plants to light during the night, nitrate uptake was reduced and the nitrate concentration in leaves did not increase. In the winter and early spring, our lettuce spends approximately half its life under lights in soil blocks and we do not harvest until March when the days are getting longer and sunlight has well surpassed the 11-hour mark.
We know you'll enjoy a good mix of lettuce from various seasons just like we do. A great place to get your seeds and learn more is at Johnny's Seeds online!