All year long

When the farmers market comes to a close on Saturday in Saratoga Springs, New York, Sandy and Paul Arnold of Pleasant Valley Farm, give a call to a local restaurant to see if the chef wants to buy what they have left over. They supply the farmers market and local restaurants with fresh produce for at least 10 months of any given year. Pleasant Valley is able to grow during that time span thanks to the succession planting they’ve been practicing for 28 years on their farm in Argyle, New York.

In some respects the planting season starts in October for the Arnolds, who live in zone 4. At this time of year, they sow cool season lettuce and greens in their three unheated hoop houses, two that are 34 feet by 134 feet and one that is 30 feet by 134 feet.

“The drop dead time to plant for winter is October 1,” says Paul.

What they’ll be planting in the last week of September are transplants of pac choi, garden kale, Asian greens, spinach and Swiss chard, to name a few. The only exception to the Oct. 1 deadline is mustard greens and arugula, which can wait up to about one week later. In fact, arugula is one crop Pleasant Valley can do succession plantings of during the New York winter months. The key is to keep the growing cycle short and sweet.

“Choose crops that have short cropping cycles,” says Andrew Mefferd, communications specialist for protected culture at Johnny’s Selected Seeds in Winslow, Maine. He says the most successful crops to use in succession planting include, but are not limited to, heading lettuce and greens, baby leaf lettuce, radishes and turnips.

Succession planting is key to not only maximizing profits, but having a near continuous supply of fresh produce for local markets. It allows growers to maximize space under cover while optimizing quality and yield. However, it does take careful planning to keep the houses full and producing well.

“Profit is determined by how many times you can turn that area,” says Mefferd. “Try to pack in as many successions as possible.”

Growers like the Arnolds and Mefferd keep careful records of planting and harvesting dates. They also practice crop rotation in the hoop houses and other methods to ensure good soil fertility.

For instance, during the summer months, while crops are being grown in the field, the ground in the hoop houses can remain fallow and/or be sowed with a cover crop. Between crops soil amendments can be added. Lately, the Arnolds have been adding peat moss prior to sowing the next crop.

“We’ve switched from using compost to peat moss,” says Arnold. “There is no weed seed in peat moss, there’s more organic matter in peat moss than compost and we don’t need the extra nutrients — we can add the organic bagged fertilizers, most of which are plant based, not animal based.”

“Some people add fertilizer every time they till up the ground between growing a short crop, like lettuce,” Mefferd says. “Many people add fertilizer at the beginning of the season for a long crop like tomatoes, then side dress throughout the season. People use everything from compost to prepared organic fertilizers, depending on local pricing and availability.” He adds that some growers are starting to use the flowable liquid fertilizers that will go through drip tape.

Pests and diseases are controlled by crop rotation and having good air flow. Mefferd has added fans in his houses, which helps to control powdery mildew and bottom rot, two common ailments in covered environments. Excessive heat can also be a problem, especially with cool-loving greens. Shade cloths and air circulation are key to keeping it cool, says Mefferd.
 

Winter/spring harvest

The Arnolds can harvest healthy-looking greens in the dead of winter. But come March, some of their produce might look a little worn out in the houses. So they rip the crops out, making way for a new batch of greens that can supply farmers markets and restaurants going into spring.

“It’s not only thinking about winter but going all the way to the end of May because there isn’t anything coming out of the fields at that time,” Arnold says.

If you walk into one of the Arnold’s lettuce houses in the spring you may see tomatoes rising above a sea of leafy lettuce. They plant determinate tomatoes and even short season vine crops in among the lettuce in early May. This not only maximizes space in the hoop house, it also brings another crop to market a little earlier than usual because it is being grown under cover while the weather is still on the chilly side.

After harvesting a late spring/early summer crop of greens and other vegetables, the Arnolds may leave the houses empty over the rest of the summer. However, in late summer they can get a crop of cherry tomatoes going that will produce right up until the winter chill sets.

The key to a timely harvest and maximizing space in hoop houses and greenhouses is in choosing the right varieties. Mefferd suggests experimenting with different varieties of the same crop that can be harvested at different times. It is also possible to plant some crops, such as spinach, by transplants for an early harvest, and then direct seed another crop of spinach for a little later harvest. It is all in the timing.

Johnny’s has prepared charts for succession planting of several vegetables and herbs that can be viewed on the Johnny’s Selected Seeds website (goo.gl/39AWCN).
 

Hoop houses for succession planting

Hoop house technology and grants from the National Resource Conservation Service (NRCS) have made it possible to practice succession planting nearly year round. Crops can be grown in large unheated greenhouses like the Arnolds own, or the affordable “QuickHoops,” also known as low or high tunnels. There are also movable and portable hoop houses that can be moved by picking them up and carrying them to their new destination, or moving them back and forth on rollers.

Neil is a horticulturist and freelance writer based in Sault Ste. Marie, Mich.