15 Mistakes to Avoid When Growing Cucumbers This Season

Cucumber vines are relatively easy to grow, whether it’s your first time growing cucumbers or you have been gardening for many years.

Cucumbers are vigorous plants, but there are some things you should do (and not do) to help improve your harvest success. By avoiding these 15 common cucumber-growing mistakes, you’ll have an abundance of slicing, snacking, and pickling cukes all summer long!

Cucumber Gardening Overview

Cucumber (Cucumus sativus) is an annual, warm-season, vining plant that produces edible fruits. Assuming that only cucumbers you’ve ever tried are the standard slicing variety found at most grocery stores, you’ll be pleasantly surprised by the interesting variety of fruits these plants can produce. 

Diverse traits include green, yellow, or variegated, long, short, or rounded, and smooth or bumpy in texture.

Cucumbers are great sliced, in salads, pickled, or even in a cool summer gazpacho. The climbing vines can produce numerous fresh crunchy fruits that you can pick and eat straight from the plant.

As long as you have a sunny garden space, you don’t need to be a gardening expert to have cucumber-growing success. They can even thrive in containers!

Cucumber plants are easy to grow once you understand their basic needs. They need rich, moist, well-drained soil and plenty of nutrition because these plants require a lot of energy to grow. They also need adequate space but can be grown in rows, hills or mounds, raised beds, and trellises.

15 Common Cucumber Growing Mistakes

Save yourself a lot of time and struggle by learning from others’ mishaps with their own troublesome cuke crops and beginner mistakes. Here is how to avoid the most common cucumber mistakes.

Improper Seed Storage

You can buy fresh cucumber seeds every year, and there are plenty of really cool cucumber varieties to try. When storing seeds from year to year, keep track of how old they are. Cucumber seeds will stay viable for up to five years if stored properly. Older seeds will not germinate as well as fresher seeds, and at some point, the germination rate will drop to zero. 

The seed age and how the seeds are stored affect the germination rate. Keep your seeds in an airtight container to keep out humidity. Store them in a cool, dry location to help keep them as fresh as possible. Check your seeds before you plant them. Cucumber seeds should be firm, smooth, and off-white in color. Discard any that appear soft, mushy, or moldy.

Starting Too Early

Cucumbers are a warm-season crop, and the plants are very sensitive to cold. Starting cucumbers indoors is unnecessary, but it is helpful for northern growers to get a jump start on the season. These seeds do very well directly sown in the garden. Cucumbers grow fast and mature as quickly as 50-70 days, so you should have plenty of time to grow healthy vines. Generally, late spring or early summer is a good time to start cucumbers.

Timing and patience are key. Wait until the temperature has warmed enough. Ideally, you will want to start your seeds outdoors after all danger of frost has passed. Wait until the daytime temperatures reach the mid-70s, and nighttime temperatures stay above 50°F.

Cucumbers thrive in the heat. Plants grown in too-cool temperatures will grow slowly or not at all. Plants will be stressed and may not flower or produce fruits. If the temperature drops below freezing, it will kill your cucumber plants. 

If you decide to start cucumbers indoors, don’t rush to transplant your tender seedlings outside. Again, you should wait until the air and soil temperatures have warmed and take several days to harden off the seedlings before transplanting them (forgetting to harden off is another common cucumber mistake).

If outdoor temperatures drop into the 40s or below, you should cover your young plants with a floating row cover to protect them from the cold.

Poor Soil Quality

Excellent soil quality can contribute to growing great plants, and poor soil quality can ruin your crop. Cucumbers thrive in warm, rich, fertile soil. In addition to high fertility, they will do best with a soil pH of 6.0 to 6.8.

The ideal soil for cucumbers will contain plenty of organic matter to both provide nutrients and help hold soil moisture. The soil should be well drained so that your plants are never sitting in wet, fully-saturated soil. 

When preparing a cucumber bed, mix in some organic matter. You can add mature compost from your home compost bin, or you can buy compost, such as worm castings or well-aged and composted manure.

Don’t plant your cukes directly in the compost – you need more than just compost in there for ideal growth, and compost that’s not fully broken down might heat up and cause damage to the plants. Instead, mix the compost thoroughly with your existing garden soil for the best blend and balance. Mix the organic compost to a depth of 6 to 8 inches, where most plant roots will develop.

Not Enough Sun

One of the worst mistakes you can make when planting cucumbers is seeding them in an area with too much shade. Cukes love bright sunlight and need at least 6 hours of bright sunlight per day.

The morning sun is best because it’s bright but not as intense as the late afternoon sun, plus it helps dry off the morning dew and therefore helps prevent the leaves from staying unnecessarily wet. 

Choose a garden location where your plants get plenty of sunlight and aren’t lingering too long in the shade. Some light afternoon shade, particularly in warmer climates, can be appreciated. Cucumber leaves can burn and turn brown in hot, dry climates if the sunlight becomes too intense for too long. 

Not Watering Enough

It may not be enough if you are waiting for the rain to water your plants. You don’t need to worry in areas that get regular rainfall each week, but any time there’s a drought, you must add some supplemental watering.

Cucumbers like to have uniformly and regularly moist soil conditions: not too dry or wet. Since cucumber fruits are mostly water, it’s important to ensure they get enough water to grow well.

So what is the ideal amount of water? 1 to 2 inches of water each week is generally a reasonable amount. Cucumbers that suffer from a lack of water will have some problems. The fruits will be bitter and unpleasant tasting.

Fruits may also grow in a stunted way with poor texture inside. Fruits grown with sufficient watering will be sweet, crunchy, and uniformly dense throughout the inside of the fruits. 

Improper Watering

There is a “right” way to water your plants and a “wrong” way to water your plants. It’s best to do it correctly when you have to add some water to help keep the soil moist.

Use a soaker hose or a long-handled watering wand to get the water to the roots where it’s most needed. Improper watering can lead to several problems, like stunting growth and accidentally inviting diseases. 

Water long enough to ensure the water penetrates the soil surface enough to reach the roots, where the plant can absorb moisture through its roots. Also, keep the water stream low, aiming for the soil rather than the plant leaves.

Sprinkling water on the leaves will increase the moisture and humidity around your plants, creating the perfect habitat for fungal diseases like powdery mildew to thrive. Drip irrigation is ideal.

Crowded Plants

There’s no need to crowd your cucumbers. You’ll grow healthier plants and more fruits by giving each plant plenty of space. Cucumbers grow on vines, and these vines can be long and sprawling. If you plant them too close together, they will cover a large patch of ground and directly compete with each other for sun, water, and soil nutrients. 

The two most common ways to grow cucumbers are planted in raised hills so they can sprawl on the ground or planted with a trellis so they can climb up. Hill-grown plants should be placed so each mound contains a single plant and the plants are spaced 1 to 2 feet apart. Trellis-grown cucumbers can be spaced about 1 foot apart and allowed to grow vertically.

Too Many Weeds

No garden plant likes to compete with weeds, and cucumbers are no exception. Weeds compete with your cucumbers for sunlight, water, and nutrients. Weeds also provide plenty of habitat for insect pests to hide out. A weed-free garden will allow the plants you care about to grow and thrive with minimal interference. 

If you have just a few cucumber plants, especially small ones, you can hand-pull the weeds around them. In a larger area, try using a small hand cultivator or hoe to remove the weeds around your garden plants quickly. Don’t spray the weeds around your garden plants with herbicides because you will risk harming your garden plants as well. 

No Mulch

Mulch offers major benefits to cucumbers. Use organic biodegradable mulch, like straw, shredded leaves, or even compost, to help enrich your soil. Mulch is also a great way to help retain soil moisture and also to help keep the weed populations down. Mulching with organic materials is a great investment for your garden. 

Other ground cover materials include newspapers, cardboard, and special weed-blocking fabrics. These will help control weeds, and if they are water permeable, they can help retain soil moisture, but they won’t do anything to help enrich the soil. Weed-blocking fabrics can also be very expensive and eventually degrade and end up in the trash. The best mulching investment will be something that will give the added benefit of soil enrichment.

Insufficient Fertility

Do you have to fertilize cucumbers? Fertilizers will help improve yields and keep plants healthy. Start your plants by sowing seeds in highly nutrient-rich soil with added compost. If needed, fertilize a couple of weeks before you transplant in new plants. It’s possible to grow a crop of cukes without adding any extra fertilizer, but you’ll have a better crop if you give them a mid-season nutrient boost.

When the plants start to flower and set fruits, it’s time to fertilize. I would recommend using an organic fertilizer of some sort. If you choose a commercial general-purpose vegetable garden fertilizer, follow the directions for product use closely.

If you’d prefer to skip the fertilizer, use a side-dressing of organic compost worked several inches into the soil around each plant. Either way, adding fertilizer mid-season will really help keep your plants healthy and producing!

Not Using a Trellis

One of the best ways to grow cucumbers is by using a trellis. Since these plants are vines, they love to climb. If you grow them without a trellis, they will happily sprawl along the ground, making them less accessible to pollinators and more vulnerable to chewing pests. The plants will be more crowded, and your fruits will get dirty from lying on the ground.

Growing on a trellis, your plants will have lots of access to sunlight, pollinators, air circulation, and space. Trellising also keeps the fruits off the ground, keeping them clean and away from pesky slugs and snails. You can also easily see your entire crop and have easy access when it’s time to harvest the ripe cucumbers. 

A trellis doesn’t have to be expensive or complicated, nor does it have to be very large. If you plant your cucumbers near a fence, they will climb the fence like a trellis. You can buy a straight upright trellis or a fancy, arched walk-through trellis. You can even make your trellis from wood or sturdy fencing. Anything tall and sturdy enough that your plant can climb up would make a good trellis.

Waiting for Problems to Get Worse

If you see something that doesn’t look quite right with your cucumber plants, don’t wait for it to worsen before doing something about it.

Whether it’s an infestation of insect pests, yellowing leaves, or rotten spots on the fruits, if you wait for a problem to get worse, it usually will. Identifying and treating problems promptly is your best chance to prevent them from getting worse. 

If you notice a problem, first try to identify what it is. Look for signs and symptoms such as visible insects, wilting leaves, yellowing leaves, discoloration, or damaged fruits.

The sooner you can identify the cause of your plant’s distress, the sooner you can start to correct the problem and continue growing a healthy crop. If you ignore problems entirely, it’s possible you will lose your plants and your entire cucumber crop. 

Not Rotating Crops

It is a mistake to grow cucumbers in the same location every year. Since they are heavy feeders, they will deplete soil nutrients quickly.

Rotate them with plants like beans or cover crops that will help enrich the soil. If you can’t rotate your crops, you must pay close attention to soil nutrients and add extra nutrient-rich soil each year to keep the soil healthy. 

Another reason to rotate your crops is to prevent the buildup of plant-specific diseases in a certain area. If you have cucumber pests and diseases, they will more easily reinfect plants grown in the same spot as the previous year. Rotate crops at least every year, but if you can wait 3 or 4 years before planting the same crops in the same locations, that’s even better.

If you’re growing plants in containers, this becomes a little easier in one way. You can use the container you planted your tomatoes in one year for a different crop the next with ease if they’re similar in size. It’s also possible to move your plants around the garden to reduce disease pressures.

Improper Harvesting

Cucumbers are easy to harvest, but it’s also easy to damage the vines if harvested incorrectly. The ripe fruits hang from the vines, and they don’t let go easily. Don’t try to pull or twist the fruits because this can easily damage the vines or even accidentally uproot the entire plant. 

Harvest the fruits in the mornings when the plants are still relatively cool. Use a knife or a clean, sharp clipping tool to snip through the stem just above the end of the fruit. After harvesting, if you aren’t going to eat them right away, store your cucumbers in the crisper drawer of your refrigerator. Try to consume them within a week. 

Harvesting Too Late

Don’t wait too long to harvest your cucumbers. If you bought seeds, look at the estimated time until harvest. Most varieties will start ripening within 50 to 70 days of starting seeds. If you don’t harvest them promptly, you’ll have unappetizing fruits. They will become tough and start to turn yellow at the ends. Overripe cucumbers will also have a spongy texture and taste bitter.

Each cucumber variety will ripen at a slightly different time, and different varieties will display different ripeness characteristics. Plan to harvest a standard green cucumber like a Marketmore when it’s between 5 and 8 inches long.

Pickling cucumbers will need to be picked smaller when they are very immature. Round ‘Lemon’ cucumbers will be rounded, firm, and start to turn from green to yellow. And the extra-long English cukes will typically take a bit more time and be ready to harvest when they’re longer, even up to 12 inches long.

Frequently Asked Questions

Final Thoughts

Cool and crunchy, cucumbers are a gardening favorite. You can grow these refreshing fruits if you have a sunny garden location with rich, moist soil. Remember these tips to keep your plants healthy and help avoid potential problems:

• Stay alert for any problems that may arise. 
• Deal with pests and diseases promptly. 
• Protect your plants from cold temperatures.
• Grow cukes in ideal conditions for healthy plants.
• Use mulch and keep pulling the weeds.
• Give plants plenty of space, and try growing on a trellis.
• Fertilize your plants to maintain their vigor.
• Harvest cucumbers properly and before they are fully mature.
• Grow your plants with good companion species.