Success with Growing Cucumbers

A Spacemaster cucumber plant in our hoophouse on April 23.
Photo Pam Dawling

Cucumbers are often overlooked, and now we are at the slower time of year, we can think over some crops we’d like to improve on. Cucumbers provide juicy crunch and, if they get enough water while growing, good flavor that conveys the essence of summer meals.

Cucumbers can also help with hydration in hot weather. I well remember a hot day when I was rototilling. I was getting thirsty, had drained my water bottle, but didn’t want to stop until I had done as much tilling as was humanly possible that day. My luck was in! Next to where I was tilling was a row of cucumbers. I slowed the engine, grabbed a ripe cucumber on the drive past, and sank my teeth into it! Instant gratification! I quickly felt revived. Plus – no packaging, no food miles!

My book, Sustainable Market Farming, includes a chapter on cucumbers and muskmelons. Here is about a third of that information about cucumbers.

Cucumber varieties

Cucumbers are warm-weather crops, usually direct sown, and maturing 55–60 days later. They are very easy to grow, apart from dealing with pests and diseases! They include two types: slicers and picklers.

Among slicers are the standard American types (open-pollinated Marketmore types and hybrids such as Generally), European varieties such as Telegraph (60d OP) and long slender Asian ones such as Suhyo Long (60d OP). Asian varieties do not have the disease-resistance of varieties bred for US climates.

As I said in my post Vegetable Seed Varieties for 2024, our favorite slicing cucumber has been renamed Generally (66d F1, resistant to Cucumber Mosaic Virus (CMV); Downy Mildew (DM); Powdery Mildew (PM); and scab).

South Wind slicing cucumber.
Photo Common Wealth Seed Growers

In 2023 we tried South Wind from Common Wealth Seed Growers. South Wind (55d OP) is resistant to DM, PM and tolerant to BW. We were pleased with its sweet taste and lack of bitterness.

Pickling cucumbers are usually smaller than slicing cucumbers, and they remain crisp when pickled. Some kinds are harvested relatively large, and sliced to make pickles. Others are picked small and pickled whole. Pickling cucumbers can also be eaten raw. We like the small-leaved Little Leaf, also known as H-19 and Arkansas Little Leaf (56d OP, resistant to ALS, ANTH, Bacterial Wilt (BW), CMV, DM, PM and scab) not only because of its disease resistance but also for ease of recognition. We often have inexperienced helpers, and we say: “If the plant has small leaves, it’s a pickler, so pick small.” We have also liked Cross Country (57d F1, resistant to ANTH, ALS, DM, PM, scab, but susceptible to BW)

For an early hoophouse crop, we grow Spacemaster (60d OP, resistant to CMV and scab), a bush-type, full-sized variety.

“Burpless” is not genetically connected with bitterness. Some varieties have a recessive bitterfree gene, but they are just as likely to cause burps in susceptible individuals. Bitterfree varieties include Marketmore 80, Marketmore 97, Diva and European and Dutch greenhouse varieties (which stay mild even under drought conditions), Bitterfree varieties attract fewer cucumber beetles.

Both slicing and pickling cucumbers are available in gynoecious (all female) varieties. To make sure the fruits will be pollinated, these seeds come packaged with 10%–15% seeds of a pollinator variety (sometimes dyed so that growers can ensure some get in every planting). Olympian, Generally and Diva are gynoecious. The flowers with miniature fruit behind the petals are female.

Parthenocarpic varieties set fruit without pollination. These can be kept under rowcover for extending the season or to keep pests off for the entire life of the plant. Little Leaf, Telegraph and Diva are parthenocarpic.

Flowering cucumbers. Photo by Alexis Yamashita

Crop requirements, seed specs, yield of cucumbers

Cucumbers require a fertile, well-drained soil with pH 6–7 and plenty of sunshine. They have no frost tolerance. Adequate water is especially important in the seedling stage and during fruiting.

Cucumber seed specs: 1000 seeds/oz, 36 seeds/g. 0.5 oz /100′, 6 oz. /1000′ at 6 seeds/ft (100 seeds, or 11g/m at 2.5 cm spacing).

Cucumber yield can be around 260 lb/100′ (388 kg/100 m), and the amount to grow could be 10–15 lb (5–7 kg) per person for the season. Unless you are growing parthenocarpic varieties, you will need ten to twenty bee visits per flower during the one day the flower is open, for a good-shaped and -sized fruit to grow.

Sowing cucumbers

Soil temperatures should be at least 60°F (15.5°C), preferably 70°F (21°C), so you might do transplants early in the year. Cucumber seeds will not germinate at a soil temperature below 50°F (10°C). We transplant our first planting and direct sow the rest.

For direct sowing we make a furrow 0.5″–0.75″ (1.3–1.8cm) deep, water the furrow if the soil is dry, put one seed every 6″ (15 cm), pull the soil back over the seeds and tamp down. We cover with hoops and rowcover or netting until the plants start to flower (about a month) as we have many pests and diseases. Once flowering, we remove the cover, hoe and thin to 12″–18″ (30–45 cm). Cucumber rows need to be 3’–6′ (1–2 m) apart.

It is possible to sow through black plastic mulch by jabbing holes in the plastic and popping the seeds in. This method leads to earlier harvests, as the mulch warms the soil, and there will be no weeds.

New Spacemaster bush cucumber transplant in a bed with old winter spinach, young snap peas and baby lettuce mix.
Photo Pam Dawling

Transplanting cucumbers

Cucumbers are not very easy to transplant, so choose a method that minimizes root damage, such as soil blocks or 2″ (5-cm) deep cell flats that are easy to eject plants from. Sow 2–3 seeds per cell 0.5″ (1 cm) deep. Single (thin to one plant per cell) by cutting off weak seedlings at soil level. Keep temperature above 70°F (21°C) during the day and 60°F (16°C) at night.

Sow four weeks before you intend to plant out, and harden the plants by reducing water before transplanting. Warm overcast conditions late in the day are best for transplanting, and rowcover (on hoops to reduce abrasion) can be used to provide sheltered conditions. Cucumber transplants are often leggy and should be planted so that the entire fragile stem up to the base of the leaves is below soil level.

Caring for the cucumber crop

In bare soil, hoe soon after the seedlings emerge, and thin the plants as needed. Drip irrigation and plastic mulch can do a lot to improve the quality, yield and earliness of melons. Plastic mulches prevent weeds during the critical weed-free period as the vines grow. They can also reduce cucumber beetle numbers, as they deter egg laying and larval migration.

Avoid working the crop (including harvesting) when the foliage is wet, as fungal diseases spread this way.

Succession planting of cucumbers

Because old plants are more likely to yield bitter cucumbers, succession planting is very worthwhile even if you have no pests. We grow five plantings of outdoor cucumbers and one early one in the hoophouse. Our second and fourth outdoor sowings include picklers as well as slicers.

Our sowing dates now are Mar 1 (to plant in the hoophouse April 4 or so), March 25 (to plant outdoors April 20), May 23, June 22, July 16 and Aug 6. Aug 6 is about as late as it is worth sowing here, where the first frost can be Oct 14. We use rowcover on cold nights for this late crop. As a rule of thumb, in spring, make another sowing when the first true leaf appears in the previous sowing. In summer, make the next sowing when you have 80 percent emergence of the previous planting.

Insect pests of cucumbers

As always, encourage beneficial insects and predators to reduce pest numbers. Soldier beetles (Pennsylvania leatherwings) and wolf spiders are good predators.

Striped cucumber beetle in a squash flower.
Photo Pam Dawling

Spotted and striped cucumber beetles cause feeding damage and transmit bacterial wilt and squash mosaic virus. Rowcover or insect netting will keep beetles from vines, but will need to be removed when the female flowers open, except for parthenocarpic varieties. Some people report good control using the yellow plastic sticky traps along with the cucumber beetle lure sachets sold by Johnny’s Seeds.

Another approach is to grow a trap crop such as Cocozelle summer squash, Seneca or Dark Green zucchini, or Hubbard squash along the edge of the field. The trap crop is then flamed or tilled in when pest numbers build up. If all else fails, and action is imperative, Spinosad will kill them. Neem doesn’t kill them, but does deter them.

The brown marmorated stink bug (BMSB), Halyomorpha halys, has over three hundred host species, including almost any fruit or podded crop. It can cause tremendous damage and, so far, has no reliable methods of control, organic or otherwise. It has several generations per year in the South. Predatory stink bugs, assassin bugs, spined soldier bugs and two native egg parasitoids will reduce the BMSB numbers, but may not give adequate control. Also see eOrganic Stink Bug Management Using Trap Crops in Organic Farming.

Low-cost management tactics include growing parthenocarpic under cover throughout growth and harvest. The High Tunnel Pest Exclusion system using 40%-50% shade knitted shadecloth to cover tunnels is effective at excluding stink bugs.

Diseases of cucumbers

To minimize diseases, choose resistant varieties, provide favorable growing conditions, plow in or remove and compost plant refuse, and control insect pests. The downloadable Cornell University Resource Guide for Organic Insect and Disease Management has information on dealing organically with most common diseases, including Angular leaf spot (bacterial), Anthracnose (a fungus disease), Bacterial wilt (Erwinia), Black rot/gummy stem blight (Didymella bryoniae fungus), Downy mildew, Mosaic virus, Phytophthora blight, Powdery mildew, and Scab (Cladosponum cucumerinum fungus). There are good photos in Identifying Diseases of Vegetables from Penn State.

Harvesting cucumbers

I wrote on this site about Harvesting squash and cucumbers, in 2018. In hot weather some people get a rash while harvesting, from prickly leaves on sweaty skin; others just get a short-term itchiness that is cured by rinsing arms and hands in cool water.

A helpful hint is to wear long sleeves for this task. Keep a suitable cotton shirt handy to slip on before you start. But sometimes it just feels too hot. Cutting sleeves off an old shirt and hemming and threading elastic in the top end works.

Using a pole to locate cucumbers among the vines. Note the cucumber beetle feeding holes in the leaves.
Photo Pam Dawling

For seeking mature cucumbers, we use a pole to rummage in the vines. It does little damage, and you can easily feel when you hit a cucumber. To harvest cucumbers, put your hand around the fruit and use your thumb to push the stem away from the top of the fruit. Remove oversize cucumbers to stimulate continued production.

Storing cucumbers

Cucumbers can be held at 45°F–50°F (7°C–10°C) and 90% humidity for up to two weeks. They will be damaged by temperatures too cold, becoming soft and slimy. Storage near other ripening fruits or vegetables can cause cucumbers to become bitter.

Season extension for cucumbers

Late crops can be covered with rowcover to fend off a few light frosts. Pollinators won’t be able to get at the flowers, but that doesn’t matter if you already have enough pollinated fruits on the plants. It takes cucumbers about 45 days or more from pollination to harvest, so if you are having a few early frosts, using rowcover and pruning to get a last flush of fruit can be very worthwhile.