Cucumber Plant Growth Stages | Life Cycle

The cucumber (Cucumis sativus) is a staple of any summer vegetable garden. From fresh salads to canned pickles, there are plenty of ways to use a cucumber harvest in your kitchen. 

Cucumber plants are fairly low-maintenance — all they need is adequate warmth and moisture to thrive — and are a great introduction for anyone interested in growing vegetables from seed. Before you get started, however, I recommend learning about the various cucumber plant stages so you know what to expect in the coming year.

Cucumber Plant Lifecycle

Cucumbers are annuals, meaning they complete an entire life cycle in a single growing season. A cucumber plant that starts as a seed in the spring will mature, fruit, and die off by the fall of the same year.

The life of a cucumber can be broken into a few basic stages that culminate in harvesting:

  1. Germination
  2. Seedling
  3. Vegetative Growth
  4. Pollination
  5. Flowering
  6. Fruit development

Many gardeners grow new cucumber plants from seed. You can also transplant starter plants bought from a local nursery. Starter plants are typically sold past the seedling stage but just before flowering starts.

You may wish to save some cucumber seeds from the current crop to plant in future years. Keep in mind that many popular cultivars are hybrids — seeds collected from these plants generally won’t produce the same quality of fruit as the parent. For the best results, I recommend experimenting with seed collection using heirloom cucumbers that have historically been open-pollinated.

While cucumbers are typically harvested for eating when the skin is green, the seeds inside are not fully developed until the rind is yellow or orange. The fruit must remain on the plant as the seeds mature, so be sure to take this into account when calculating the length of your cucumbers’ growing season.

Cucumber plants do not die off immediately after fruit maturation. Since their life cycle is complete, however, you can feel free to remove harvested plants from your garden at this time. Alternatively, you can leave plants to die back naturally with the year’s first frost.

Cucumber Plant Growth Timeline – Timelapse Video

This short video is a beautiful illustration of a cucumber plant going through each stage of growth from a seedling to a fruiting plant.

Growing Cucumber Timelapse - Seed To Fruit

Growth Stages Of A Cucumber Plant

Most cucumbers are ready for harvest 50 to 75 days after germination. The exact length of a cucumber plant’s life cycle will depend on the variety, as well as seasonal and environmental conditions.

Climate Zones’ regional weather will play a role in the growth rate as with any fruiting or flowering plant, sunlight is critical to success. Cucumbers need at least 6-8 hours of direct sunlight per day to grow optimally. They also require temperatures and prevailing weather conditions to be favorable around 70°F.

Varieties each variety of plant will have different characteristics that will influence the growth rate. For example, three popular types for home growers include:

  • Pickling – Bush Pickle 48 days to maturity
  • Bush – Fanfare 63 days to maturity
  • Vine – Marketmore 76 days to maturity

1. Seed Germination

Cucumber seeds are readily available from a variety of sources. You can find many popular cultivars at any home and garden store. For more niche cultivars, I recommend ordering from an heirloom seed catalog or website.

I recommend planting cucumber seeds at least 1 inch deep. Provide consistent moisture pre- and post-germination but do not let the soil become soggy.

Cucumber seeds also require warm temperatures to germinate and grow. Because of this, planting should begin at least 2 weeks after your area’s last frost date. New seeds can be sown every 3 or so weeks to create a continuous harvest throughout much of the summer. 

Cucumber seed germinating
Cucumber seed germinating

For an earlier first harvest in cool climates, you may want to start cucumber seeds indoors to be transplanted into the garden at a later date. I recommend using a heat mat under your seed-starting setup to maintain the ideal temperature for germination.

On average, cucumber seeds will sprout in 3 to 10 days when kept in temperatures between 80 and 90°F. If the environment is allowed to drop below 80°F, sprouts may not emerge for over 10 days after planting. Seedlings may be delayed or completely fail to grow if exposed to temperatures below 70°F.

2. Cucumber Seedlings

When cucumber seedlings first emerge, they have two round leaves called cotyledons. These cotyledons are part of the seed’s embryo and are quickly replaced by mature foliage. All leaves that appear after the cotyledons should be slightly heart-shaped with serrated edges.

Once cucumber seedlings reach 4 inches tall, it’s time to thin out the weaker plants. This step creates ample space for the remaining seedlings to grow strong root systems without unnecessary competition. 

Transplant cucumbers started indoors once they reach several inches tall and the temperature outside is at least 70°F. Most varieties perform best when planted 1 ½ feet apart from each other.

If you’re growing vining cucumber plants, you’ll also want to provide a support system at this stage. I prefer to use wooden stakes or tomato cages that the vines can be loosely tied to as they grow.

Cucumber Seedling
Cucumber Seedling

3. Vegetative Growth

Once the plant begins to grow, it will accelerate into a sprawling mass of large leaves over the next 30-60 days of vegetative growth, climbing and creeping until they reach a length of approximately 6-8 feet. The leaves will grow facing the sun to harness its light for the demanding task of producing flowers and fruit. As it grows the vies will produce tendrils on the back of the leaf nodes, that enable the plant to cling onto surrounding structures to climb towards the sun.

In warmer climates, it’s possible to companion plant cucumber with corn crops, using the corn stems for support, whilst the lower portion of the cucumber plant offers shade to the corn root, retaining moisture within the soil.

For efficient use of space, most growers prefer to use a trellis to grow cucumbers vertically, allowing for a higher fruit yield for per square foot. This also offers the opportunity to create a wall of leaves that will turn to the sun, as well as keep the fruit of the ground and flowers closer to the flight path of pollinating insects.

4. Flowering and Pollination

Cucumbers are naturally monoecious. Monoecious plants produce separate male and female flowers that must cross-pollinate with each other to produce fruit. (Note that cucumbers are self-fertile, meaning that flowers from the same plant can pollinate each other.)

Male flowers can be identified by their pollen-covered stamens. Meanwhile, female flowers have swollen bases that, when fertilized by male pollen, develop into cucumber fruit.

All cucumber flowers are yellow with a tubular shape similar to that of morning glory. The first male flowers should appear 35 to 55 days after seed germination. Female flowers on the same plant will appear about 1 to 2 weeks later.

While wild cucumbers follow this flowering pattern, some newer cultivars are gynoecious. Gynoecious plants have predominantly female flowers instead of an even mix of the two sexes. According to Iowa State University, gynoecious cucumber varieties have the capacity to produce much more fruit in a season as long as they are planted alongside monoecious plants with male flowers. In my experience, most gynoecious cucumber seeds for sale are mixed with monoecious seeds to ensure fertilization.

Improving Pollination

Cucumbers like zucchini and pumpkins are monoecious plants, meaning they have both male and female flowers on the same plant. Therefore insect pollination is simple in terms of a single plant host that offers the insects both flower types. However, it can also make pollination challenging unless you have several plants offering insects enough open male and female flowers simultaneously.

To improve the pollination rate, it’s a good idea to grow companion plants with a view of attracting pollinating insects such as bees and flies. I can recommend plants such as borage, dill, calendula, or sunflowers as reliable options.

Cucumbers grown in greenhouses or in areas that lack natural pollinators may need to be pollinated by hand. I recommend using a soft paintbrush to transfer pollen from male flower pistils to the females. Perform this task every week and you will see a significant improvement in fruit production and a reduction in flowers dropping off the plant.

5. Early Fruiting

Female cucumber flowers will begin to show signs of fruit production approximately 10 to 12 days after pollination. The cucumber’s time to harvest will vary depending on the variety and the intended use. For example pickling cucumber can be harvested when between 3-6 inches, whereas salad cucumbers will typically grow to 6-10 inches in length. Smaller cucumbers can be harvested as soon as 7-14 days after the flower shows signs of fruit production, with larger fruit taking an extra 7 days or more to develop.

Cucumber fruit forming behind flower
Cucumber fruit forming behind the flower

What Does A Cucumber Look Like When It Starts Growing

Despite what some people believe, the fruit of a cucumber plant does not grow inside of or replace the flower. Instead, cucumbers develop from a swollen portion of the stem above each female flower. If you look at the image above you can clearly see the mini cucumber forming behind the flower.

6. Mature Fruit Development

Successfully fertilized flowers should be obvious after a couple of days as the base of the flower swells and elongates. It will take anywhere from several days to a couple of weeks for the fruit to ripen. If the flower begins to die off with no changes to the adjacent stem, fertilization has failed and no fruit will develop. 

Technically speaking, cucumbers are usually picked and eaten before they are fully mature. Cucumbers tend to develop hard seeds and a bitter flavor as they mature, making older fruit far less appetizing. 

If you intend to collect seeds for future years, leave some fruit on the plant to finish maturing. Use plastic mulch or row covers to protect the remaining cucumber plants from an early frost.

Cucumber ready for harvesting
Cucumber ready for harvesting

When To Harvest Cucumbers

On average cucumbers will take 50-75 days from germination, through to maturity and harvesting. However, regional weather variations as well as cucumber varieties will affect the growth rate. So it’s worth taking a closer look at the plant and checking the fruit for visible signs of maturity and ripeness.

Pay close attention to the size, color, and firmness of cucumbers as they ripen. Since these characteristics differ between cultivars, I strongly suggest familiarizing yourself with what the mature fruit of your planted varieties should look like.

I recommend harvesting cucumbers on the early side whenever possible. The fruit should be firm but not overly tough. 

Ripe cucumbers typically have medium- or dark-green skins. Keep in mind, however, that some cultivars have unique coloring. If you’re growing a type of yellow or white cucumber, for example, you’ll want to research the correct color before harvesting. 

The ideal size for a harvested cucumber depends on the type and how you plan to use the fruit. Here are a few basic guidelines to follow:

  • Harvest cucumbers for pickling when they are about 2 inches long
  • Dill cucumbers should be about 4 inches long at harvest
  • Regular slicing cucumbers are best harvested between 6 and 8 inches long

If you happen to plant burpless cucumbers in your garden, you can leave the fruit to grow 10 inches or longer before harvesting. These varieties contain no or very little cucurbitacin, which is the compound that turns cucumbers bitter as they ripen. 

Harvesting fruit as often as possible is a great way to maximize productivity and head off any onset of powdery mildew, ruining your crop. A good rule of thumb is to harvest cucumbers every 2 days during the season’s peak. Leaving cucumbers on the plant will significantly lower future production.

FAQ Cucumber Plant Growth Stages

Citations

Iowa State University How do gynoecious cucumber varieties differ

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.