Cucumber: Cucumbers need very warm soil to germinate. If direct sowing wait until the soil is warm. If the weather turns cool and wet after that, just re-sow. Alternately start transplants indoors in individual peat or coir pots 3-4 weeks before transplanting out into warm soil. If starting indoors, use bottom heat. Transplant when the plants develop their third true leaf. If the plants are too big, they may experience transplant shock. Optimal soil temperature for germination and transplanting: 15-30°C
Sowing: Start indoors at least 3-4 weeks before the last frost. Cucumbers do not like their roots disturbed so use individual pots or “cow pots” and use bottom heat. When transplanting outdoors, plant the entire ‘cow pot” after all danger of frost has passed. Transplant in the early morning and protect the plant from wind, sun, or other elements by using a pile of loose straw, a cut milk container, shingles, or other methods of protection. It is better to harden off your cucumber plants. Space plants 23cm apart in rows 90cm apart. If sowing in peat pots plant the entire pot without disturbing roots.
Growing: Ideal pH: 6.0-6.8. Choose a location with warm, well-drained soil. or in raised beds. Add diolomite lime and compost or well-rotted manure to the bed and 250-500 ml of complete organic fertilizer mixed into the soil beneath each transplant. Cucumbers are vigorous and need plenty of nutrition and water. Use plastic mulch, plant under floating row cover, or anything to warm the soil. Once the weather warms up, keep the soil evenly moist. When plants begin to flower, remove covers so bees can access the flowers to pollinate. If fruit that is not fully pollinated will be very small and shriveled and should be removed from the plant. Most varieties produce fruits until the weather begins to cool down. Regular picking promotes better production. Try to water the soil only, keeping the leaves as dry as possible. Vines can reach 1.5-2 meters in length, so growing them upward onto a trellis makes good use of garden space. Fruits that grow hanging into space tend to be straighter than those that form on the ground.
Harvest: For a continuous summer harvest, make successive plantings every 2 to 3 weeks until about 3 months before the first fall frost date. You must keep picking the cucumbers regularly because if they get too big, the plant will stop producing fruit. About 1 month before the first frost, start pinching off new flowers so plants channel energy into ripening existing fruit.
Several diseases attack cucumbers, but problems are mostly caused by cultural practices that stress the plants. Keep the garden clean and tidy, remove diseased material, and do not compost cucumber plants unless you’re able to get a hot compost pile going. Avoid overwatering and do not directly spray water onto the leaves. Plant in a well-drained site and use long crop rotations of 3 or more years. Whenever possible, use disease-resistant varieties.
If plants get off to a good start, few pests will bother them. If pests are present, young plants are best protected with floating row covers that are removed when flowering starts. Aphids, cutworms, and thrips can be a problem. If gardening east of the Rockies, cucumber beetle can become problematic.
The fungus causing fruit to rot occurs during periods of high humidity. Pick these fruit off and keep plants from being overwatered or too cold.
Angular Leaf Spot: Angular leaf spot is one of the most widespread diseases of cucumber. The disease is caused by a bacterium, and the initial symptoms are small, water-soaked spots that develop on the undersides of leaves. These lesions expand until they become limited by the larger secondary veins in the leaf, giving the spots an angular shape. On susceptible cultivars, the spots may be surrounded by a yellow halo. Under humid conditions, a milky ooze exudes from the infected tissues. This ooze dries, leaving a white crust covering the lesions. The disease can also affect stems, petioles, and fruit. Fruit lesions are small 3 mm in diameter and circular with light tan colored centers, and fruit will become deformed if infected when young. The angular leaf spot bacterium can be seed-borne, present on transplants, and survive in the field on crop debris. The pathogen can survive in dry leaf material for up to two and a half years which is why hot compost is important if adding any cucumber components. The bacterium infects cucumber plants through openings, such as stomata, hydathodes, and wounds. The pathogen is spread by splashing water, insects, or contaminated equipment. The disease spreads easily when plants are wet so do not work in cucumber gardens during wet periods. Copper-based bactericides can help slow the spread of angular leaf spot if treatments begin when symptoms first appear, and the addition of an EBDC fungicide, such as mancozeb, will enhance the effectiveness of the copper treatment.
Bacterial Wilt The bacterial wilt pathogen is transmitted by the striped and spotted cucumber beetles. The most critical infection period is from seedling emergence to the time when canopies start to close. Wilt symptoms can develop at any time, but the disease is most damaging early in the season when plants are growing rapidly. At first, only a few vines may be affected, but the symptoms can quickly spread to the entire plant. Eventually, vines become necrotic and die. A field diagnostic test for the disease involves cutting a wilted runner near the crown, pressing the cut surfaces together, and slowly pulling the pieces apart. If thin strands of bacterial slime form between the two cut surfaces, then bacterial wilt is probably the cause of the wilting symptoms. The wilt pathogen does not overwinter well in soil or crop debris. The bacterium most likely overwinters on weed hosts and volunteer cucurbit plants.
Phytophthora crown and root rot