Cucumber: Direct Sow Vegetable, May be Started Indoors
How to Sow and Plant
Sowing Seed Indoors:
- Direct sowing is recommended, but to get a head start you can grow cucumbers indoors 3-4 weeks before the last frost in individual biodegradable pots indoors. Sow 2-3 seeds per pot.
- Sow seeds ½ inches deep in seed-starting formula
- Keep the soil moist at 70 degrees F
- Seedlings emerge in 7-14 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- Thin to one plant per pot.
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Sowing Directly in the Garden:
- Sow in directly in the garden in fertile, warm soil after danger of frost has passed. Cucumber seeds will not germinate in soil colder than 60 degrees.
- Sow seeds 3 inches apart in groups of 4-6. Cover with ½ inch of fine soil.
- Space groups 19 to 26 inches apart each way.
- Keep evenly moist.
- Seedlings emerge in 7-14 days.
- Thin to 3 or 4 strongest seedlings in each group when they are 1-2 inches high.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating.
- Cucumbers have a shallow root system, mulches help retain soil moisture and maintain even soil temperatures.
- Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1-2 inches of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- As plants grow mulch to control weeds, keep fruits off the ground and conserve moisture
- Do not move the vines, they are easily injured.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- When cucumber seeds are direct-sown along a cucumber fence, vines can be trained to grow upright for easy picking and to save space for other plants to grow. Good companion vegetable plants are direct-sown radishes, bush snap beans, and transplants of compact herbs, peppers, eggplants and tomatoes. Attract bee pollinators by planting daisies such as sunflowers, cosmos, zinnias and coneflower, and mints such as bee balm, sage, oregano and lavender. More bees mean more chances flowers will be pollinated and develop into fruits.
Harvest & Preserving
- Like most vegetables, cucumbers are tender and tastiest when harvested young before their seeds are fully developed.
- Slicing cucumber varieties are generally ready for harvest when about six to eight inches long; pickling cucumber types at three to five inches- both in about 50-60 days from seeding.
- To avoid damage cut fruit from the vine rather than pull
- Don't allow the fruits to become overripe on the vine as this signals to the plant that the seed-development process is nearly complete and it will shut down.
- Keep mature cucumber fruits picked to encourage further production. During hot weather cucumbers grow very fast, you may need to harvest every day.
- Harvest the cucumber fruits early in the morning before the sun hits them for the best flavor and texture.
Common Disease Problems
Alternaria Leaf Spot: Small, round reddish brown spots, usually with a yellow halo, form on the upper surface of the leaves. Severely infected leaves turn brown, curl upward, wither and die. Fruit are not usually infected but can suffer from sunscald due to leaf loss. This disease is worse in warm, wet or very humid weather. Burpee Recommends: Avoid getting water on the foliage. Remove infected plant parts and do not work around wet plants. Provide plenty of air circulation. Contact your Cooperative Extension Service for fungicide recommendations.
Anthracnose: This is a fungus disease that attacks the fruit as it is ripening. Irregular brown spots develop on the leaves. Infected fruit develop sunken black spots that may have white mycelia during wet weather. The spots enlarge and turn black; the fruit rots. Extended periods of heat and humidity facilitate anthracnose growth. The fungus overwinters in diseased plant debris. Burpee Recommends: Provide sufficient space between plants for good air circulation, avoid overhead watering which can spread the fungus spores, keep a clean garden, remove and discard all diseased plant material and rotate crops.
Bacterial Wilt: Leaves turn brown, stems wilt and shrivel, the infected plants die. Burpee Recommends: Remove and destroy plants showing signs of the disease. Control cucumber beetles, which spread the disease. Contact your Cooperative Extension Service for recommendations.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Seed Rot and Damping Off: This is a fungus disease that affects seeds and seedlings. Infected seeds will not spout. Infected seedlings can have brown thin stems and the plants will quickly die. Burpee Recommends: Do not sow seeds until the soil has warmed to 65 degrees. Plant seeds in a raised hill that will warm up earlier. Keep beds moist but not water logged.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Cucumber Beetles: Beetles may be spotted, striped or banded and can be very harmful. Beetles are usually ¼ to ½ inch in size. Beetles start feeding as soon as they hatch and can kill or slow the growth of the plants. Beetle larva can also bore through the roots of the plants. Beetles can also transmit diseases from plant to plant. Burpee Recommends: Knock off adults into a jar of soapy water and destroy them. Spade the soil to destroy dormant beetles before you plant. Use a row cover to prevent adults from feeding on young plants. Consult your Cooperative Extension Service for other insecticide recommendations.
Squash Bugs: Adults are 5/8 inch long and gray or brown. Squash bugs give off a foul odor when crushed. Young nymphs have light green abdomens and black heads and legs. As the nymphs grow they will change color. Eggs are found in groups on the underside of leaves eggs will be yellow or brown. Squash bugs will feed on leaves and fruit. Burpee Recommends: Brush off adults into a jar of soapy water and destroy them. Check for clusters of eggs on the back of leaves and destroy them. Use a floating row cover to prevent females from laying eggs on plants.
Spider mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Misshapen Fruit: Cucumbers can become round or misshapen when they receive too much water. Burpee Recommends: Mulch to help moderate moisture levels.
Why does my fruit have a bitter or poor flavor? Bitter flavor can be caused by a number of factors including: hot and dry temperatures, overwatering, or poor soil fertilizer. Cucumbers have shallow roots; make sure the soil is moist but never waterlogged. Test your soil for a nutrient deficiency.
Why do I have lots of leaves but no flowers? The plant is likely getting too much nitrogen, which triggers it to grow foliage, and not enough phosphorus, which favors flowering and fruiting. Choose a fertilizer that has a balanced ratio of the three major elements, such as 10-10-10, or where the middle number (phosphorus) is larger than the first number (nitrogen) such as 2-3-1.
Why do I have flowers but no fruit? Cucumbers are “Dioecious”, meaning that they have both male and female flowers on the same plant. Male flowers usually open first and female flowers have a baby fruit behind the flower. Both types of flowers must be present to have fruit set. Flowers may abort because of heat or cold or drought stress OR flowers abort because of a lack of pollination OR the plant is not ready to set fruit and the plant is self-aborting flowers to conserve and direct energy towards more growth.
Why did my green cucumbers turn yellow? The fruit has over matured and must be removed. An over ripen fruit is usually bitter. Pick fruits as soon as it is the right size to use.
Why are my cucumbers curved? Incomplete pollination of the female flower will cause deformed, curved growth, as can drought stress and being grown on the ground. Training plants on a trellis is the best way to ensure long, stra