Growing Cukes in Containers
In many ways, containers and cucumbers are a perfect match. Cucumbers love the warm soil a container provides, so you can plant earlier in spring and harvest longer into the fall. It's easier to keep an eye on the demanding water needs of cucumbers when they're grown in pots on a deck or patio close to the house. And the space-efficient varieties now available are quick maturing and high yielding, so you can plant successive crops through the summer and enjoy a steady supply of fresh cukes all season long.
Plant Bush Varieties
Almost any cucumber variety can be grown in a container, but bush varieties offer good disease resistance and yield high-quality crops in much less space."These plants have a bushy, round shape, as opposed to a more viney growth habit," says Al Burkett, a cucumber breeder with Peto Sluis Seed Company in Woodland, California. "With shorter spaces between the leaves, they branch quicker and tend to set the fruit sooner and closer to the base of the plant," he explains. And even though pickling quarts of cucumbers isn't the goal of most container gardeners, some bush varieties like 'Pickalot Hybrid' will even produce yields comparable to standard-sized vines.
To get the best yield from your container crop, it's important to understand the flowering characteristic of the variety you choose. The most foolproof method is to pick a cucumber that sets fruit "parthenocarpically," meaning without pollination. One of the best varieties of this type for containers is 'Arkansas Little Leaf' (also called 'H-19 Little Leaf'). It has very attractive, small, triangle-shaped leaves and produces an abundant crop of two- to three-inch-long picklers throughout the season. "It tends to start slowly, but it's strongly branched, can grow to more than three feet in diameter and really pumps out fruit," says Rob Johnston of Johnny's Selected Seeds in Albion, Maine.
If you want to plant a mix of varieties, some of which will require pollination, make sure to choose at least one monoecious type, which bears both male and female flowers. 'Fanfare' is an excellent choice for a bush-type slicer. "This monoecious plant can get large--up to four feet in diameter--but is worth growing in a container because of its increased disease resistance and the better shape and quality of its fruits," notes Ken Owens, a breeder of slicing cucumbers at Peto Sluis.
Some cucumber varieties are "gynoecious," which means they bear only female flowers. Seeds of a male pollinator plant are included in the seed packet. Gynoecious plants can be more productive because every blossom has the potential to fruit. "You need to grow at least seven plants of a gynoecious variety, however, to insure the male pollinator is present," Burkett notes. "Without a pollinator (or a monoecious variety), you run the risk of having only female flowers on your plants--and no cukes," he explains.
For a really small-vined (two to three feet in diameter) gynoecious variety, try 'Bush Baby'. "It's similar in appearance to 'Arkansas Little Leaf', but the plant has a more compact habit and the pickles are more uniform," says John Gale, president of Stokes Seed Company in Buffalo, New York.
Even with plenty of male and female flowers on your plants, you'll need one more thing to insure a good fruit set: bees. Cucumbers grown close to a house or in an urban setting may have limited bee activity. One solution is to play Cupid with a cotton swab and pollinate the blossoms yourself, transferring pollen from the male blossoms to the females (those with the tiny, immature fruit at the base).
Choose Pots and Soil Mix Carefully
The type of pot you choose is critical to a successful crop of cukes. "I use wooden or plastic containers that are 12 deep and about the same diameter for each two to three plants," says Linda Yang, author of The City & Town Gardener: A Handbook for Planting Small Spaces and Containers (Random House, 1990) and a lifelong container gardener in New York City. Clay pots tend to dry out too quickly. Cucumbers love water so much that on sunny days you'll be watering twice a day just to keep up, she says.
Make sure the container has at least four drainage holes on the sides at the base of the pot. Holes on the bottom tend to clog. And don't bother putting a layer of stones in the bottom of the container for better drainage. The best drainage is the right soil mix. "You can use a soilless mix, especially if weight is a consideration," says Yang. A good example of a soilless blend is two parts peat, two parts vermiculite or perlite and one part fine sand. A mix with sand is heavier but holds water and fertilizer longer. "I also mulch with bark chips for moisture retention," Yang adds. "To insure enough nutrients for good growth, mix a time-release fertilizer, such as Osmocote, in the soil before planting," recommends Sam Cotner, Extension horticulturist at Texas A&M University in College Station and the author of Container Vegetables (Texas Gardener Press, 1987).
Most cucumber varieties, even the short-vined ones, will benefit from trellising. "I use a tomato cage, fitted to the container," says Cotner. "The cucumbers vine through it and stay straight and clean," he explains.
In a cool climate, place the containers in a south-facing exposure for full sun. In climates where summer temperatures go up in the 90s, however, you may need to make some adjustments to keep container crops from overheating. Avoid black plastic containers and give the pots an eastern exposure (the heat of a southern exposure can kill the pollen). Elevate them at least four inches off the ground, especially on concrete and brick patios.
Proper Watering is Crucial
The commonly recommended method of determining when to water is to stick your finger into the soil to your second knuckle, and if it's dry at that depth, water. That technique may work fine for clay pots that evaporate water evenly throughout the pot, but plastic and wooden pots can have a dry layer on top and moist conditions below where the roots are. Too little water can cause wilting, bitter cucumbers and insect and disease problems; too much, and the roots may rot.
"A better technique is to push a pencil or popsicle stick down into the soil," says Cotner. If the soil sticks to the pencil after you pull it out, you don't need to water. If it comes up clean, it's time. Add a liquid fertilizer diluted to half strength once a week if the plants look like they need a boost. "Always water from the top of the container until the water comes out the bottom to leach any fertilizer salts out," Cotner adds.
If the container has dried out too much, the soil will contract, creating a space between the soil and the edge of the container. "Then, when you water, it will run down that space and out of the container, leaving your soil dry," says Linda Yang. If this occurs, soak the soil mix slowly to be sure the water penetrates it.
Succession Plant for Steady Harvest
Bush varieties produce fruit for roughly four weeks during the summer, but that doesn't mean you're finished with cucumbers. About two weeks after you start picking cukes, plant another crop. Most bush types mature in about 50 days, so by overlapping your plantings, you can get at least two, sometimes three crops a year in a container.
"For best flavor, harvest pickle cucumbers when they are three inches long and slicers when they're 8 1/2 long, says John Gale. Always err on the small side. Don't be afraid to pick off and discard any misshaped or overmature fruits. "The more you pick, the more flowers and fruit the plant will produce," says Gale.
Charlie Nardozzi is senior horticulturist at National Gardening.