How to Grow Cucumbers Organically

cucumber and flowers growing on the vine

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Cucumbers are enjoyed all over the world for their crisp, refreshing flavor. They are relatively easy to grow in the home garden, and easy to preserve as pickles for later enjoyment. Here’s everything you need to know about growing cucumbers organically, from planting to preservation.

History of Growing Cucumbers

Cucumber cultivation began about 3,000 years ago in parts of India and western Asia. The crop would eventually spread eastward to China and westward through Greece to Rome, where it was often associated with fertility.

Legend has it that Roman Emperor Tiberius demanded that he be served cucumbers every day, and had his servants tend to his cucumber plants year round in specially made mobile greenhouses that could be brought indoors during cold weather.

Thanks to thousands of years of careful cultivation and breeding, modern-day cucumbers are far less bitter than their ancestors. Ancient cucumbers, like their wild cousins, would have contained high levels of cucurbitacins which are bitter compounds that are produced as a natural pest repellent.

Today, most cucumber varieties have been carefully bred to contain very low levels of these compounds. These low-cucurbitacin cuckes are typically called “burpless” because the chemical supposedly makes you burp.

Types of Cucumbers

Cucumbers, Cucumis sativus, are part of the Cucurbitaceae family (also referred to as cucurbits). Other garden crops that belong to the Cucurbitaceae family include melons, pumpkins and squash.

There are two main categories of cucumbers: slicing and pickling. Slicing cucumbers are usually 4 to 12 inches long with relatively smooth skin, and can be eaten right off the vine. If spines are present, they will generally be white. Some examples of well-known slicing varieties of cucumbers would be English, Persian, Marketmore, and Lemon cucumbers. 

Pickling cucumbers are smaller, generally about 1- to 5- inches long, with noticeably bumpy skin. These varieties generally have black spines. These cucumbers are often not as tasty straight from the vine. While large pickling cucumbers are used for dill spears, small ones like the gherkin are known for their especially tiny and bumpy fruit. While you can technically pickle any cucumber, Picklebush, Kirby, County Fair and Carolina are favorite varieties in the U.S.

Once you have chosen whether you want to grow slicing or pickling cucumbers, the plants themselves come in two distinct growth habits: bush and vine. Bush cucumber plants take up much less room in your garden and can even be grown in a pot, which is ideal for gardeners who don’t have lots of space. Vining cucumbers can grow very large and be very productive. To save space in the garden, grow your vines up a strong trellis, which also makes the cukes easier to harvest.

Get heirloom cucumber seeds and more at great prices!

How to Plant Cucumbers

Soil Preparation for Cucumbers

Before you plant your cucumber seeds in the garden, you’ll want to prepare your soil. Cucumbers need fertile, slightly acidic soil (pH 6.5-7). They can be heavy feeders, so you will want to improve the quality of your soil by mixing either compost or aged manure about 2 inches deep into the soil before planting. 

Planting Cucumbers

Cucumber seeds need to be planted about 1 inch deep in soil that is at least 70° F (21° C) to germinate well. They can be started indoors in pots to get a head start on your growing season about 3 weeks before you plan to transplant them outside. It helps to place a heating pad underneath your seed tray when starting seeds inside in order to maintain a constant temperature.

Cucumbers need warmth to grow well, so be patient and wait until at least 2 weeks after your last frost in spring to either sow your seeds outside or transplant your seedlings. Make sure you plant them in an area with full and consistent sunlight throughout the growing season.

If you have a vining variety of cucumber, plant your seeds 1 inch deep and space about 12-18 inches apart alongside a trellis in a sunny spot. If not using a trellis, give the plants 2-3 feet of space apart. If you have a bush variety, you can either sow your seeds 12-18 inches apart in rows 2 to 3 ft apart, OR sow 2-3 seeds in mounds that are spaced 18-24 inches apart. Bush varieties also grow very well in containers at 2-3 seeds per 12-18-inch pot.

Fertilizing Cucumbers

If you have already mixed in compost or aged manure during your soil prep, you will only need to side-dress your cucumber plants with fertilizer during the growing season. You will want an organic formula that is high in potassium and phosphorus but low in nitrogen. You should apply fertilizer to the soil around your plants right after planting outside, one week after blooming, and again every 3 weeks.

Special Tips for Growing Cucumbers

Water Cucumbers Consistently

The key to preventing bitter fruits is consistent watering. Give your cucumbers at least one inch of water per week, and more if the weather is extremely hot and dry. When you’re watering, avoid getting the foliage wet as much as possible, as this encourages leaf diseases like mildews. Drip irrigation is strongly recommended to help keep leaves dry and watering consistent. Mulch deeply to reduce evaporation and splashing, and to keep your soil moist.

Companion Plants for Cucumbers

Companion plants for cucumbers include beans, peas, cruciferous vegetables like broccoli and cabbage, celery, corn, dill, lettuce, marigolds, nasturtiums, radishes, sunflowers, and tansies. Avoid pairing with herbs like sage and mint that are extremely aromatic, as they can stunt the growth of nearby cucumbers. Also avoid planting with potatoes, tomatoes, melons, and other gourds. 

Separate Your Crops

Because cucumbers are in the same family as melons and squashes, sometimes they can cross pollinate if they are planted too close to each other. This won’t affect your crops, but it can affect the seeds of the next generation of plants. So if you plan to save your heirloom or open-pollinated seeds for planting next year, you will need to give your cucumbers a wide berth from your squash or melon plants—at least 20 feet.

Another reason to separate your cucumbers from other cucumbers, squash and melons is to reduce the chance of spreading pests and disease. Cukes, squash and melons all suffer from the same pests, so if one crop gets invaded or infected, you can prevent it from getting to your other crops if you give them different locations in the garden.

Cucumber Pests and Diseases

Cucurbits like cucumbers, melons and squash are susceptible to many pests and diseases. To prevent problems, it’s generally a good idea to select seed varieties that are resistant to diseases in your area, and to practice good crop rotation, mulching, and removal of diseased plant matter.

Insects

Plants are eaten or cut off near soil level.

Cutworms are gray grubs ½- to ¾-inch long that can be found curled under the soil. They chew stems, roots, and leaves. Place a 3-inch paper collar around the stem of the plant. Keep the garden free of weeds; sprinkle wood ash around base of plants.

Leaves curl under and become deformed and yellowish.

Aphids are tiny, oval, and yellowish to greenish pear-shaped insects that colonize on the undersides of leaves. They leave behind sticky excrement called honeydew which can turn into a black sooty mold. Use insecticidal soap.

Leaves turn pale green, yellow, or brown; dusty silver webs on undersides of leaves and between vines.

Spider mites suck plant juices causing stippling. Spray with water or use insecticidal soap. Ladybugs and lacewings eat mites, which you can buy and release in your garden.

Leaves yellow; tiny white winged insects around plants.

Whiteflies will congregate on the undersides of leaves and fly up when disturbed. Use floating row covers and reflective mulch to deter whiteflies. Remove infested leaves and the whole plant if infestation is serious. Introduce beneficial insects into the garden.

Holes chewed in leaves, leaves skeletonized; runners and young fruit scarred.

Spotted cucumber beetle is greenish, yellowish, ¼ inch (7mm) long with black spots and black head. Striped cucumber beetle has wide black stripes on yellow wing covers. Plant beetle-resistant varieties. Use floating row covers; hand pick; mulch around plants; plant resistant varieties; dust with wood ashes. These beetles can transmit disease, so rotate crops and cultivate soil before planting to disrupt the insect life cycle.

Holes in leaves and flowers; tunnels in vines and fruits.

Cabbage loopers are the larvae of little white or yellow moths. Moths lay their eggs on the underside of the leaves of your plants. Caterpillars feed on leaves and inside vines and fruits. Exclude moths with floating row covers, and hand-pick eggs and worms, then destroy. Plant fast-maturing varieties to promote strong growth before cabbage loopers attack. Keep garden clean.

Leaves have yellow specks that turn brown, then black and crisp; vines wilt from point of attack.

Squash bug is a flat, shield-shaped black or brownish bug with a triangle on its back; it sucks juices from plants. Remove plant debris, like dead leaves and flowers, from the garden. Trap squash bugs under boards and remove them in the morning, hand pick and destroy. Look under leaves for bugs and eggs, remove and destroy them.

Small holes or pits in the leaves.

Flea beetles are tiny pests that are dark in color, with a shiny, iridescent carapace. They jump like fleas when disturbed, earning the name flea beetles. Use floating row covers; mulch deeply around plants. Use diatomaceous earth or Neem oil to control the population.

Distorted, wilted leaves that have coarse stippling and a silvery appearance.

Thrips are very small, so it’s hard to see them with your naked eye. The easiest way to view them is to use a magnifying glass. Avoid planting cucumbers near onions and garlic because thrips are attracted to those. Huge infestations can be taken care of by using insecticidal soap.

Diseases

Irregular brown spots on the leaves, sometimes with yellow edges.

Alternaria Leaf Blight more commonly affects melons but can also affect cucumbers. The fungal spores can be carried in by wind or spread through contaminated soil and water. Wet and warm conditions favor the disease. Spray or dust with a fixed copper- or sulfur-based fungicide every 7 to 10 days. If only a few parts of the plant are affected, cut and remove those parts to prevent the fungus from spreading. If the plant is severely infected, remove the whole plant, treat or replace the soil, and start over. Don’t plant cucumber, pumpkin, squash or melon in the same location for 2-3 years. Don’t save seed from infected plants.

Yellow, water-soaked, circular spots on the leaves and fruit with dark brown to black edges.

Anthracnose is a fungus disease that spreads in high humidity and rainfall. Leaves may wither and fall. Plant may die back. Choose resistant varieties of cucumber. Spray or dust with a fixed copper- or sulfur-based fungicide every 7 to 10 days. Remove and discard infected plants. Avoid working in the garden when it is wet, which can result in spread of spores. Keep tools clean. Don’t plant cucumber, pumpkin, squash or melon in the same location for 2-3 years. Don’t save seed from infected plants.

Small, brownish, angular or circular spots—sometimes with yellow edges—or black spots on the leaves.

Angular leaf spot or bacterial spot is a waterborne bacterium which causes irregular geometric patterns on leaves. It is often carried by cucumber beetles. Avoid wetting leaves with irrigation. Prune off infected leaves and stems. Look for cucumber beetles starting early in the spring, and remove them as you see them. Use floating row covers. Plant tansy, catnip, and/or radish nearby, which can repel cucumber beetles. Plant disease-resistant varieties.

Round white powdery spots and coating on leaves.

Powdery mildew is caused by fungal spores carried by wind. Spores germinate on dry leaf surfaces when the humidity is high. Common in late summer or fall but does not result in loss of plant. Pick off and destroy infected leaves and use these strategies to control it.

Irregular yellowish to brownish spots on upper leaf surfaces; grayish powder or mold on undersides.

Downy mildew is caused by a fungus. Improve air circulation or use trellises. Use drip irrigation to prevent leaves from getting wet. Plant resistant varieties. Rotate crops. Keep garden free of plant debris and use this disease preventing spray.

White, yellow, or green lines and patterns on leaves and fruit.

Mosaic virus produces a characteristic pattern of spots and/or lines on the leaves or fruit that are white, yellow, or light to dark green. The veins of the leaves may also become very distinct and yellow. The virus is spread from plant to plant by aphids and cucumber beetles. Control aphids and beetles with floating row covers and insecticidal soap. Remove diseased plants.

Yellow, wilting leaves that appear to be drying out.

Bacterial wilt clogs the circulatory system of plants. It is caused by bacteria that is carried by cucumber beetles. One way to tell if it’s bacterial wilt is to cut a section of the affected stem and place it in a glass of water. If a milky sap oozes from the cut, it signifies bacterial wilt. Remove and destroy infected plants before the disease spreads. Control cucumber beetles.

Plants are stunted and yellow; runners gradually die.

Fusarium wilt is a fungal disease which infects plant vascular tissues. Fungal spores in the soil and cucumber beetles can carry it. Plant disease-resistant varieties. Rotate crops. Control cucumber beetles. Remove and destroy infected plants.

Water-soaked or pale green spot on leaves that turn white; fruit cracks.

Scab is caused by soilborne bacterium. Disease can be cosmetic. Plant resistant varieties. If scab occurs, change varieties next year. Sulfur may be worked into soil to make it slightly acidic and reduce disease.

Stems on older plants appear water soaked and turn into cracked brown cankers; fruits become water soaked.

Gummy stem blight and black rot are fungus diseases. Infections can girdle stems can cause collapse. Remove and destroy infected vines. Rotate crops where fungus can persist. Grow powdery mildew resistant plants.

Other Cucumber Problems

Early flowers don’t set fruit.

A couple of possible reasons: (1) the first flowers to appear are usually male; female flower appear next. Fruit is produced by female flowers. Wait until female flowers appear and are pollinated. (2) There may not be enough pollinators, mostly bees, to carry the pollen from male to female flowers. Pick off male flowers and dust the pollen into the female flowers.

Few fruits form even though plants are flowering.

Not enough bees. The more bees in your garden, the more pollination of flowers that are likely to set fruit. The average size of a squash is increased when the vine is pollinated by many bees. Pick off male flowers and dust the pollen into the female flowers.

Small fruits form then dry up.

Female flowers may have blossomed before the male flowers so the female flowers went unpollinated. When female and male flowers blossom at the same time pollination can occur and fruit can grow.

Fruits turn brown or rotten on one end.

Blossom end rot means there the plants aren’t getting enough calcium, water or both. Learn to treat it here.

How to Harvest and Store Cucumbers

Cucumbers won’t ripen further once they’re picked, so it’s important to get your timing right. Overripe cucumbers can have tough skin and taste unpleasantly bitter. Most cucumbers are generally ready to harvest in 50 – 70 days depending on the variety. Check the details on your seed packet if possible, but generally:

  • Slicing cucumbers should be harvested when they measure between 6-8 inches long. Some varieties, like Armenian cucumbers can grow longer.
  • Pickling cucumbers should be harvested when they are anywhere from 2-5 inches long.
  • Ripe cucumbers are firm and green. Yellow skin can be a sign of over-ripeness (except Lemon cucumbers, which are supposed to be yellow). 

When picking cucumbers, always use a knife or pair of garden shears to separate them from the stem about a quarter inch above the end of the cucumber. Yanking them can break your vines. Try to pick cucumbers every couple days. Leaving cucumbers on the vine to toughen and mature will decrease the production of edible fruit, but it will allow you to have seed to plant for next year, if that’s what you want to do.

Store your cucumbers in the vegetable crisper drawer of your refrigerator. They’re best eaten or pickled right away, but you can save them for up to a week in the fridge without losing much quality.

How to Save Cucumber Seeds

Some things to keep in mind before collecting cucumber seeds: 

  • Don’t try to collect seeds from cucumbers that are labeled as hybrids. Hybrid varieties are made when specific parent plants are crossbred and cannot reproduce a true copy of either parent plants. These plants are often sterile in fact.
  • Cucumber flowers can be pollinated by wind, insects, or humans, which means it’s not uncommon for them to be cross pollinated when different varieties or related plants are grown in the same area. This will compromise the quality of your seeds. Make sure you have at least 20 feet of space between your cucumber, melon and squash crops. (See cross-pollination, above.)
  • Seeds can be a carrier for agricultural diseases like various fungi, so make sure you aren’t saving seeds from an infected crop.

Seeds can only be harvested once the fruit is totally mature, so you will want to leave a few selected seed cucumbers on the vine until the end of the growing season. You should pick your seed cucumbers when the skin has toughened a bit, and is either yellow or orange.

To remove the gel around the seeds, you need to ferment them:

  • Scoop the seeds and pulp out of your cucumbers and put them into an uncovered jar with some warm water.
  • Keep jar at a temperature of 70-80ºF for 3 days. Stir the seeds daily.
  • After 3 days of fermenting, add a little more water to the jar and swish. The pulp and any infertile seeds will rise to the surface for easy removal, while the viable seeds will sink. Carefully and pour out all of the water, pulp and floating (infertile) seeds.
  • Remove the viable seeds from the bottom, and spread them out to dry on either a screen or paper towels.

Once your seats have thoroughly dried, you can store them in jars or envelopes labeled with the type, variety, and date of harvest. You can also put your seeds in the freezer for a day or two to kill any pests that may have survived the fermentation process.

Store cucumber seeds long term in a cool, dry location in a fridge, root cellar, or pantry. Your seed viability will decrease as time goes by, so try to use them within the next 3 years.

Cucumber Recipes

Cucumbers are great fresh in salads and smoothies, but can also be easily preserved by pickling them. Cucumbers have so much water in them that they don’t freeze or cook well, but as pickles, you can batter and fry them, or dehydrate them for a very unique type of “chip.”

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