How to Successfully Grow Cucumbers
Updated: Sep 27, 2020
I find cucumbers super finicky to grow in the zone 3 gardening climate! If you have previously tried growing them and it has not gone well, know that you are not alone.
There are both vining and bush varieties of cucumbers. Bush cucumbers are good for containers or small gardens. Vining cucumbers grow well up a trellis or, if you have space, they can sprawl out on your garden bed. Cucumbers are prone to disease when the leaves are wet so growing them up a trellis or on a small mound can be beneficial to keeping the leaves up and out of pooled water.
Other cucumber varieties are slicing or pickling cucumbers. Slicing varieties grow to be 6 to 12 inches long where pickling cucumbers are 3 to 4 inches in length.
Preparing Soil for Cucumbers
Cucumbers do best in a full sun location in well drained soil with plenty of compost. High nutrient levels in the soil will promote quick growth in your cucumbers during our short zone 3 growing season. Use a fertilizer high in potassium as potassium is what encourages blossoming and fruit production in plants. Another option is making a high potassium "tea" by adding a banana peel to a quart of water and letting it sit in a cool place for 3 days then using this "tea" to water your cucumbers.
Cucumbers Like Heat
Cucumber seeds are planted 1 inch deep and around 6 to 12 inches apart. To germinate they require temperatures of at least 20°C. We know these temperatures do not hold throughout our nights, even if our days are warm. This can make cucumbers difficult to germinate in a garden. If you chose the direct seed method, consider using a row cover or cloche to keep the soil warm. Uncover as soon as you begin to see blossoms. If you chose to start your cucumbers indoors, plant them 3 to 4 weeks prior to your desired transplant date. I recommend using peat pots to start your cucumbers in as they do not like having their roots disturbed during transplanting.
Many of us have had our cucumbers wilt and die shortly after transplanting. Did I mention cucumbers can be finicky? Transplanting problems likely come from either shock from change in temperatures or having their roots disturbed.
The best time to transplant your cucumber plant is once it has developed its true 3rd leaf. (Don't count the first two leaves out of the ground. These leaves will look different than the succeeding leaves and can be snipped off once the 3rd true leaf is developed.) At this stage the plant is strong enough to withstand the change and at the same time not so large as to have devolved to a stage where you will have to disturb it much during transplanting.
To prevent temperature shock take at least a week to harden off your cucumbers. (See "How to Harden off your Plants in a Week".) Cucumbers do not like temperatures of less than 5°C at any time. Plan to wait to transplant until night temperatures are 5° or above consistently. For me this means waiting until the middle of June until my cucumbers go outside. Other options are using a greenhouse, cold frame or covering to insulate the plants from the cool night air.
To protect cucumber plants roots during transplant gently tear or cut the bottom of the peat pot off, leaving the sides intact and plant it like this. Form a small mound around the stem to keep it from sitting in water.
Always water any type of plant in as soon as possible after transplanting to help the soil settle around the plant and to prevent further shock.
Watering Your Cucumbers
Cucumbers love consistent water in well drained soil. Avoid getting the plant leaves wet when watering. If your plants are on a sprinkler system, watering in the morning vs. the evening allows the leaves to dry off sooner. Mulch will benefit your cucumbers by retaining moisture for longer periods and keeping the plants out of pooled water. Do not over water.
Encouraging Fruit Production
Cucumbers plants have both male and female blossoms. The female is the one with the mini looking cucumber at the base of the blossom and is the one that produces cucumbers. The purpose of the male blossom is to pollinate the female but it is not fruit bearing. If you want to be sure your blossoms get pollinated you can do this yourself by using a Q-tip and gently brush it over and around the male blossom and then the female blossoms. Cucumbers will produce more if picked often.
Cucumber Pests and Disease
Pests and disease that attack your cucumber plant include aphids, cutworms, thrips, cucumber beetle and powdery mildew. If your established plant begins to show singes of wilt even when watered check for these.
Planting marigolds, dill and/or cilantro next to your cucumbers will discourage pests. Nasturtiums attract aphids but can withstand their attack. Planting them near your cucumbers can keep the aphids off your more sensitive cucumber plants.
Other companion plants include brassicas, corn, pole beans, carrots, sunflowers, lettuce, onions, peas and tomatoes.
Avoid planting cucumbers near potatoes or sage.