Growing cucumbers in an unheated greenhouse or high tunnel is challenging. If you follow these basic steps, you’ll enjoy an abundance of cucumbers for pickles, salsa, salads.
Of course we are in mid-season, but I want to start at the beginning so we’re all on the same page. This will set you up for Sweet Success (one of my favorite cucumbers, by the way) for next year.
1. Seeds: Begin with varieties that are suitable for greenhouse growing. Look for vining, not bushing, cucumbers that are either gynoecious (generate only female blooms, yet produce fruit) or parthenocarpic (set fruit without pollination). This eliminates the need for bees and other pollinators. Favorites include: Sweet Success, Manny, Green Fingers, Corinto, Diva.
2. Sowing: Sow indoors in early to mid-spring. For us, around April 15 to plant out in the greenhouse in June. Cucumbers are heavy-feeders which means they prefer (demand!) the best organic fertility you can create. After potting up the seeds to the next size pot (4-inches or so) provide them with soil enriched with compost, seaweed or kelp meal, comfrey (chopped or as a tea), and other sources of organic nitrogen, which I’ll cover shortly. Seaweed and comfrey, provide a rich smorgasbord of trace elements.
3. Transplanting: Cucumbers prefer warm feet (soil) with a neutral pH of 6 to 7. Whether you plant them out in the ground or in containers, make sure you do this when the soil and air temperature have warmed up nicely.
Containers: The darker the better.
Soil: If you can, bury soil ‘heat tape’ or non-LED Christmas rope lights four inches deep near the roots. Either way, give them the sunniest spot!
4. Care while growing: Once the plants are planted out, install some sort of support for the fast-growing climbers. Netting, lattice, and training them to single strings work well.
String tips: Cucumbers prefer fuzzy, jute-like natural fibers over slick, artificial ones. Tie the string off to a horizontal bar set as high as practical then bring it down to the soil. Make it taught by securing it to a stake poked in the ground at the base of the plant, or onto a weight, such as a good-sized chain link.
As you train the maturing plants, there is one more thing you need to monitor: side shoots. Here’s where I follow the wisdom of Eliot Coleman, master of year-round growing in Maine. Prune off every sucker and flower until the plant is two feet tall. (I don’t have a lot of vertical space to begin with, so I pinch off suckers and flowers until the plant is just one foot tall).
At that point, the cucumber roots should be healthy and big enough to support fruit production. As the plant grows, continue pinching the suckers and flowers (but leave one cucumber at each node) until the stem has reached the top bar.
Allow the plant to continue growing up and over the bar. At this point, you can let one sucker grow in addition to the main “mother stem.” Thus you’ll have two stems trailing over the support bar.
At first, the stem bending over the bar will want to arch upwards and grow in a U-shape. But as cucumbers form, the weight will encourage it to change its direction.
Allow each stem to grow back down to the ground.
Air: Crack open windows and keep fans running 24/7 to prevent mold, downy mildew, and other diseases.
Water: Keep soil evenly moist, but not soggy.
Food: Liquid fertilizers (or teas) made from fish, manure, compost, seaweed, or comfrey provide pick-me-ups during the season. Another key, but overlooked liquid fertilizer is old-fashioned urine.
Some people call it peecycling. Urine is an excellent source of nitrogen, phosphorus and many other nutrients. Urine is not only safe to use as a fertilizer, but communities are now focusing on removing pee from the waste stream. Think about it: We make this amazing fertilizer with our bodies and then we flush it away with gallons of another precious resource.
Toilets, in fact, are by far the largest source of water use inside homes, according to the EPA. Wiser water management (how about spring-loaded faucet handles that turn off when you let go?) could save vast amounts of water. Hello drought-stricken western U.S.
5. Teamwork: Before you pinch, train, and otherwise fuss with your cucumber plants, be mindful of what you are doing. Thoughts are things. Thoughts generate energy. Give your plants notice, a heads up, say, the day before, by letting them know what you plan to do next.
6. Harvest: When your cucumbers reach harvest size, don’t delay picking so the energy is distributed to the rest of the plant. To pick a cucumber, grab hold and gently twist until it separates from the plant. And say, “thank you!”
Follow these tips and you’ll have so many cucumbers that your neighbors will pull the curtains closed when they see you coming.
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