How to Extend Your Harvest Season

When frost comes, do you shut down your field activity for the winter, or would you like to extend your fall harvest? Would you like to bring in an extra revenue stream to the farm with winter crops? Or both? With the technology now available in the farming industry, you can extend your harvest season in many ways. Some use low-tech resources you already have around the farm; some are high-tech that may require an investment in infrastructure. However, you extend your harvest you benefit from premium prices. Let’s look at how your farm can be more profitable.

30% - 100% Profit from Winter Crops

Before you get too far into extending your harvest season think about how you’ll market your “out of season” produce. You can continue selling your winter harvests wholesale and make 30%, on average, of the retail price. As long as you keep your overhead low and only want to extend your harvest a few months, that might be an option.

Have you considered selling retail – direct to consumers? There may be some extra costs associated with a “farm to fork” operation, but they are offset by the higher profit margin.  According to 2019 USDA statistics (the latest available) a head of green leaf lettuce sold wholesale for $0.31 and was sold in grocery stores for $1.72.

Selling your produce to restaurants, school cafeterias, and health care facilities such as hospitals will bring you closer to the grocery retail price while giving your community nutrient-dense food.  Investing in a booth at a local winter farmers market will probably bring you even more revenue, especially if you’re farming without synthetics. Consumers like to see the face behind their food. Knowing “their farmer” means paying a premium for your high-quality product.

Extending the Fall Harvest of Crops You’re Growing

Row Covers for Late Fall Harvest

As a vegetable producer or fruit farmer, you already know putting row covers over your crops will protect your product from frosts, at least the lighter ones. Row covers have low up-front costs and give you about another month’s worth of production. But if you’re a corn/soybean farmer row covers aren’t part of your farming equipment. To see how you can increase your farm revenue move on down to the section on “High Tunnels or Hoop Houses” to see how you can add winter crops to your farm.

For vegetable and fruit producers; a little more effort will allow you to continue your fall harvest into winter when the snow flies.

Low Tunnels or Caterpillar Tunnels

These temporary structures are used to cover specific rows of high-value crops in your fields. You probably have the materials around the farm; heavy-weight

Row tunnels extend harvest

row covers, PVC pipe or metal tubing, 2x4s, and some rocks.  This is low-tech but may extend your harvests for another 2-3 months, allowing you to get premium prices for “field grown” crops. If you don’t have some of these items, they’re easily available at your local hardware or online - and relatively inexpensive.

I’ve used PVC tubing because it’s easier to cut and bend. The tubing keeps the row cover just above the vegetation of your crops so frost doesn’t touch the leaves or fruits.  When you’re setting these up be sure to use the Heavy Weight row cover material, so it doesn’t rip.

Low tunnels aren’t heated, so they’ll only protect cold-hardy crops for late fall, early winter harvests. In a mild year, you may be able to harvest up to December if you’re growing in Zone 5, for example. They’re usually 6-8 ft high and 10-20 feet wide, but you can easily adapt them to the planting configuration and height of plants you’re trying to protect. Anchors hold them in place, and they have to be vented manually. I’ve found 2x4s helpful to hold the edges down, with a few large, strategically placed rocks. Making your low tunnel any higher than 8 feet may create a wind issue.

High Tunnels or Hoop Houses

High tunnels have a higher upfront cost but can extend your harvest throughout the entire winter. To offset the higher cost, grow higher-value crops. Brassicas such as kale, broccoli and cauliflower do well in an unheated hoop house. Winter lettuce, spinach, Bok choy, Chinese cabbage, onions, and shallots also do well. All these vegetables have to be planted by September so they can sprout and get some growth before it gets too cold. They can be planted in beds in the high tunnel or in pots arranged for convenient watering. They’ll hibernate in December and January (no harvest, time to shop for the Holidays) but come alive again when the days start to get longer in February.

High tunnels, or hoop houses, are considered a conservation measure by the USDA Natural Resources Conservation Service.  Because you’re supplying the nutrients and water for your plants needs there’s no runoff of excess fertilizers and more efficient water use. The NRCS offers financial assistance for high tunnel construction (but not greenhouses) through its EQIP program. If you’re not familiar with this program see how you could benefit.

The USDA has reports on wholesale prices for vegetable crops. Study the one for the area near you to determine which crops will give you the greatest profit. Combine that information with what crops are the most cold-hardy and you’ll make the most of your high tunnel investment. 

A remote thermometer is valuable for a hoop house, to monitor both extreme cold and extreme heat.

It’s amazing how hot an unheated hoop house can get on a sunny winter day. In the middle of winter, it can easily get up to 70 degrees F. (21 degrees C.)  inside even when it’s 25 degrees F. (-4 degrees C.) and windy outside.  You’ll have to vent both high and low tunnels on sunny days manually or your crops will roast. I have a lawn chair in my hoop house for such days. It’s very pleasant to tramp through the snow, slide through the hoop house door, then take off my winter jacket and snow pants. Shorts and a T-shirt are perfect in January in the hoop house for reading a good book. And all that oxygen from the plants is good for the health!

Heated High Tunnels for Winter Crops

High tunnels can be heated, although they aren’t very energy efficient. The best way to heat your high tunnel is to heat the soil. There are numerous systems to get heat into the soil or under your pots, from creating a compost pit to setting up a boiler and hot water piping system.

Whatever heating system you use add a low tunnel inside the hoop house to contain the heat only around your crops. It’s a waste of energy to heat the entire hoop house for plants that may be only 3 feet tall.  Hot air rises and the top of your hoop house will be warm, with less heat remaining around your plants. You’ll have to watch the temperature carefully; those low tunnels can get very warm in the middle of winter.

High tunnels are constructed of polycarbonate or plastic, with solid polycarbonate sidewalls. Plastic is the least heat efficient unless you use two layers and add an inflation system between the layers. Blowing air between the plastic layers is great insulation.  

It’s Important You Select Cold-Hardy Cultivars for Winter Harvest Crops

It’s important to plant cold-hardy cultivars for either low tunnel or high tunnel cultivation. Read labels. There are many Asian Greens that are extremely cold-hardy and have high value in a salad mix, especially if you decide to sell retail.

September plantings will get most of their growth before frost but will slow down when freezing temperatures hit. That doesn’t mean they’re done, but the harvests will become less.

Around the end of January, when the days start getting longer, you’ll see a renewed vigor in your crops. Harvesting winter lettuce and selling directly to the consumer at retail gives you a much higher profit. Selling wholesale produce brings you 30% of the retail price. Don’t you want the other 70% for your extra effort?

Auxiliary heat sources such as propane and natural gas should be used sparingly, otherwise you’ll eat up your profits.

Greenhouses for Winter Crops

Interested in creating a second revenue stream on your farm? Investing in a greenhouse opens up many options to you. It’s heated, well insulated, has the proper lighting, water (and usually a restroom), and electricity.

It’s an investment in your farm, just like a pole barn, or new tractor. Greenhouses run in the neighborhood of $50,000.00 and up for a commercial structure. But with that extra heated space you can grow high value crops without synthetics for health-conscious consumers such as chefs at up-scale restaurants or customers at your local winter farmer’s market.

Many vegetable crops are now grown in greenhouses year-round. Consider branching out into more exotic or hard-to-find products – greenhouse space is very valuable real estate. It may be a learning curve for you but offering microgreens, heirloom tomatoes, and multi-colored lettuces, for example will more than pay for the extra effort.

Growing Winter Crops Under Cover is Not Like Field Growing

There are pros and cons to growing under cover, whether a high tunnel or a greenhouse. The only difference between low tunnels and field growing is the frost protection, otherwise they’re considered field crops.

The environment inside a high tunnel or greenhouse is different from field production in many important ways. You control the fertility and moisture content of the soil. Be sure to add compost and mulch to the undercover growing area.  Watering with a humic acid product, such as Humic Land, will keep the soil microbial community alive and well.

Pros:

  • Many foliar diseases are eliminated because there’s no rain splashing soil up onto leaves
  • There’s a significant increase in biomass, yield, and quality
  • Integrated Pest Management is easier in an enclosed growing environment
  • Can gain new markets by having products available that can’t be grown outdoors
  • Customers pay premium prices for “out-of-season” produce
  • Retain skilled farm employees by offering year-round employment
  • Pollination, if needed, can be accomplished through the addition of a bumblebee hive

Cons

  • Watering must be done by grower; drip irrigation system is the most efficient
  • Salts can accumulate because rain can’t leach them out of soil (test soil every year)
  • Because of high biomass production extra attention must be paid to soil fertility, this includes plants grown in-ground as well as pot-grown plants.
  • Higher humidity and temperatures are hospitable to certain fungal diseases and insect pests
  • Bumblebees die off in winter but in a heated greenhouse may continue pollinating (this is an area of scientific research).

Extend Harvest to Winter or Expand Farm to Include Winter Crops

There are many options available to you to make more money on the farm. The higher returns with winter crops come with a higher investment. But isn’t that how life is? The more you invest in yourself the greater the return. However, you decide to increase your farm revenue, you know the quality of your soil determines the quality of your product.  That’s especially important if you decide to grow under cover.

I hope this was useful. Please share with your neighboring farmers and subscribe to our newsletter for more information.

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