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Cucumbers are an easy-to-grow summer crop. If you have a sunny location and a plot of fertile soil, you can grow your own cucumber plant. Even without a garden, you can grow a compact cucumber plant in a container! But what growth stages does a cucumber plant pass through from seed until fruiting?
Cucumbers (Cucumis sativus) are popular garden plants that are widely cultivated. The many cultivars of cucumber can be divided into three main types: pickling, slicing, and seedless.
Pickling cucumbers are very small and dense, the slicing cucumbers are stoutly oblong and have prominent but edible seeds, and the “seedless” varieties are longer with tiny seeds. But not all cucumbers are oblong and green; “lemon cucumbers” are rounded and yellow!
Cucumbers are a favorite for snacks, salads, smoothies, and even cool summer soups. They are full of water and taste quite refreshing on a hot summer day. And since cucumber is a warm-season crop that loves heat and sun, this is an excellent combination.
If you’re ready to grow your own cucumber plants, read on, and we’ll dig right into the growth stages of cucumbers and what you can expect during each stage.
9 Growth Stages of Cucumber Plants
| Stage | Key Notes |
| Selecting Seeds | – Flattened, oblong, off-white – Use seeds no more than five years old – Choose from many interesting varieties |
| Sowing Seeds | – Sow seeds outdoors in late spring or early summer – Sow seeds indoors, 3 weeks before transplanting – Sow in loose, moist soil – Plant 1-inch deep – Keep seeds warm and moist |
| Germination | – Roots sprout – Keep warm and moist – Seeds take 3-10 days to germinate |
| Cotyledons | – First leaves emerge – New plant requires bright light – Cotyledons appear after germination and last for about 14 days |
| True Leaves | – First true leaves emerge – Cotyledons will fall off – Plant starts growing rapidly – True leaves emerge 7-14 days after cotyledons – Thin seedlings – Transplant indoor-grown seedlings |
| Vegetative growth | – The plant focuses all its energy on growing longer and larger – Requires bright sunlight and regular soil moisture – Watch for pests and diseases – Rapid vegetative growth from the emergence of first true leaves until first frost |
| Flowering | – Bright yellow flowers appear – Separate male and female flowers – Flowers require cross-pollination – Flowers attract many insect pollinators – Flowers begin to appear 40 to 55 days after planting – Healthy plants flower until first frost |
| Fruiting | – Fruits form with female flowers – Fruits grow quickly – Fruits mature 10 to 12 days after flowering – Watch for pests |
| Harvest | – Harvest 3 to 8-inch-long fruits – Begin harvesting 50 to 70 days after planting – Use a sharp knife or pruners to cut fruits from vine – Store fruits in the refrigerator for 7 to 10 days – Enjoy fresh, cool, crunchy cukes! |
If you start a cucumber plant from seed, you can expect to harvest your first fruit anywhere from 50 to 70 days after planting. If you buy a young cucumber plant from a garden center, you could see your first fruits in as little as 20 days after planting, depending on the age of the plant you purchased. As long as the plant stays healthy, you can have a steady supply of cucumbers for the rest of the growing season.
Let’s take a closer look at each stage and learn how to make each stage a success, from selecting seeds to harvesting your crop.
Seed Selection
You can have a lot of fun selecting cucumber seeds. Try something new and different that you’ve never tried before. There are traditional oblong green cucumbers, or “lemon” cucumbers that are small, round, and yellow! You can grow miniature cucumbers for pickling or extra-long cucumbers, which are surprisingly sweet and excellent in salads.
You will also have a choice in growth habits. Most cucumbers are vining and will grow up to 6-foot-long vines. These vines grow really well on a trellis or other upright support. If you want to stay with something more compact, try a bush variety of cucumber. These plants stay just 1 or 2 feet long and are great for containers, raised beds, or other small spaces.
Cucumber seeds that have been stored in a cool and dry location can stay viable for up to 5 years. The germination rates will decline over time. If you have seeds over five years old, starting with some fresh seeds may be worthwhile. Also, if you notice your seeds are soft, mushy, brown, or moldy, throw them out and buy some new seeds.
Cucumber seeds are readily available at nurseries and garden centers or anywhere else that sells garden supplies in the spring. Any online seed catalog should have cucumber seeds as well. If you just want to grow a few cucumber plants, any seed pack will have more than enough seeds to get you started.
Sowing Seeds
Cucumber seeds can be sown indoors or outdoors. If you have a warm and sunny window or grow light, you can plant seeds indoors to get a head start on the growing season.
Cucumbers also grow well when directly sown in the garden but are very sensitive to cold temperatures. Just wait until the outdoor temperatures have warmed enough that the soil is around 70 degrees and that plants will not risk frost or temperatures less than 45 degrees.
Starting Seeds Indoors
To start seeds indoors, you will need a sunny location or grow light. Cucumber seeds need warmth, and a seed-starting heat mat is a great way to give them a boost.
If you don’t have a heat mat, that’s fine too. Place them in a sunny window or another bright, protected location where you can keep an eye on them. The ideal seed-starting temperature for cucumbers is around 70°F.
Plan to start your seeds indoors about three weeks before you want to plant them outside, which probably means starting them inside in mid to late spring. Prepare your pots with fresh seed-starting soil. Plant 2 or 3 seeds per pot, pushing them 1 inch deep into the soil. Keep the seeds warm and moist until they sprout.
Starting Seeds Outdoors
Cucumber seeds do fine when started outside, directly sown in the garden. Before planting any seeds, however, prepare your soil in advance to give your plants a great start.
The ideal cucumber location has full sun with at least 6 to 8 hours of bright sunlight each day. Cucumbers need rich, well-drained soil with a pH of 6.0 to 7.0.
Cultivate your soil to approximately 8 inches deep before planting. If your soil is dense, full of clay, or extremely sandy, you can improve soil quality by adding some compost or well-aged manure and thoroughly mixing it in before planting.
Cucumbers also need plenty of warmth. Don’t start them outside too early, or your plants will suffer. Start the seeds outside at least 2 weeks after the last frost date when the soil temperature has warmed to at least 70 degrees. Cucumbers are sensitive to cold and will die in a frost, so protect the seedlings during their early days and try to keep them warm.
Plant the seeds 1 inch deep and keep them keep warm and moist until they germinate.
If you plan to grow plants on a trellis, space a cluster of 2 or 3 seeds every 1 foot along the trellis.
For growing in hills, create a mound of soil approximately 1.5 feet across. Space the mounds approximately 2 feet apart. Plant a cluster of 2 to 3 seeds per mound; you will thin them later.
Space the rows 5 to 6 feet apart so that plants will have plenty of room to sprawl along the ground, and you will have space to walk between them. Sow seeds every 4 to 6 inches along the rows. You will thin them later.
Germination
Viable cucumber seeds in warm, moist soil can require between 3 and 10 days to germinate. The ideal temperature to stimulate germination is around 70 degrees or a little warmer.
If the temperature is too cool, your seeds may take longer than 10 days. Keep the seeds warm and moist the entire time you are waiting for them to germinate.
During germination, the hard outer layer of the seed, also known as the seed coat, softens and cracks open. A tiny root emerges and starts to grow down into the soil.
You probably won’t see this stage because the seed will still be completely underground. Once the root grows down a little bit, a tiny green sprout will appear above the soil surface. This is the first sign you will see that your seed has successfully germinated.
Cotyledons
You’ve been waiting patiently, and your seeds are still warm and moist. One morning, you notice that something has finally happened! A tiny green sprout has emerged from the soil.
This little sprout starts as a thin, weak stem with two tiny, furled leaves. In a few days, the stem has straightened, and the two little oval-shaped leaves spread apart.
These first two leaves you see are called cotyledons. The cotyledons of a cucumber plant are bright green and oval-shaped. They will appear in a pair opposite each other. You will probably notice that they are not the same shape as the true leaves of the cucumber plant. The first true leaf will emerge next. You can expect the cotyledons to last approximately two weeks.
True Leaves
The first true leaf will emerge anywhere from 10 to 14 days after you see the cotyledons. While the cotyledons are smooth and oval-shaped, the first true leaf will be slightly rough-edged and more rounded in form. After a few true leaves develop and the plant starts to grow rapidly, the cotyledons will turn yellow and drop off.
When the seedlings have grown a couple of true leaves and are around 4 in tall, it is time to thin them. Rather than pulling them out, which can disturb the roots of any close neighbors, remove the extra seedlings by snipping the extra plants’ stems with sharp scissors.
If you started seeds inside – Thin the seedlings to one healthy plant per pot.
If you started seeds outside – You will need to thin the seedlings, but the spacing of your seedlings will depend on your growing methods.
Transplanting young plants – If you started seedlings inside or bought young plants from the local garden center, you can follow these same spacing guidelines as you transplant the seedlings into your garden.
If you grow your cucumbers on a trellis, thin them to 1 plant per foot. Position the trellis immediately next to the plant so that as it begins to grow upwards, it will soon touch the trellis. Cucumbers will naturally climb on any nearby support structure.
If you plant your cucumbers in mounds or hills, thin them to 1 plant per mound.
The rows should be spaced 5 to 6 feet apart to allow for the vines to grow and for you to walk between them. For rows of plants, thin seedlings to one plant per 1.5 to 2 feet along the row.
Before you transplant your indoor-grown plants into the garden, harden them off for a week or so. All this means is that every day, place the seedlings outside in a somewhat protected area where they will be exposed to a limited amount of direct sunlight and natural outdoor temperatures.
Take them in each night. This allows the young, tender plants some time to acclimate to outdoor extremes before transplanting them into the garden.
Vegetative Growth
Cucumbers grow fast. Once your plants sprout and start to develop their true leaves, they will grow rapidly. Mulch around the young plants to help keep the cucumber fruits clean and help offer some protection against soil-dwelling pests like slugs.
If you haven’t already installed a trellis for your vines to grow up, it’s not too late. Cucumbers are climbing vines and will reach for any sort of fence or framework to grow on.
Allowing your plants to climb is a way to practice vertical gardening and is an excellent way to save space! Trellises also offer other benefits, such as improving airflow, improving pollinators’ access, and allowing you easier access to your plants (and their fruits).
During this time of rapid vegetative growth, keep your plants consistently moist. Plan to water them every week unless you receive plenty of rainfall. Uneven moisture, particularly extended periods of dry soil, can cause fruits to grow poorly and taste bitter.
Use a soaker hose or other technique to water plants from the bottom. Try to avoid spraying water on the leaves. Wet foliage is an invitation to diseases like powdery mildew that thrive in high-humidity environments.
If you have just a few plants or are growing them in a container, you can easily water with a hose or watering can, controlling the flow of water just towards the base of the plant and around the roots.
Pests and Diseases
Several pests and diseases can affect cucumbers. A few of the most common issues are listed here.
Squash Bugs
- Large white, green, or brown insects that love cucumbers and squash
- Squash bugs suck plant sap and cause plants to weaken and die
- Remove and kill any visible squash bugs and their egg clusters
- Remove plant debris to reduce hiding places for overwintering insects
- Destroy heavily-infected plants
Cucumber Beetles
- Small yellowish-green beetles with black spots or black and yellow stripes
- Beetles eat numerous holes in leaves
- Remove plant debris and weeds where beetles may hide
- Rotate crops
- Avoid over-use of pesticides
Bacterial Wilt
- A bacterial infection that causes the plant to wilt
- Infected plants will not recover
- Destroy infected plants; do not compost
- Bacterial wilt is spread by cucumber beetles
Powdery Mildew
- White or gray coating on leaves
- Most common in high humidity environments
- Good air circulation can help prevent mildew
Here are a few general tips to help keep your plants healthy and avoid pests and diseases:
- Rotate crops each year
- Remove dead plant matter to keep the garden clear
- Grow disease-resistant varieties
- Grow companion plants to deter pests
Companion Plants
Companion planting is a way to grow multiple different plants together in a way where one species benefits another. Companion planting can provide structural support, shade, attract pollinators, improve soil quality, or repel pests. There are several good companion plants for cucumbers.
| Cucumber Companion Plants | ||
| Beans | Cabbage | Celery |
| Corn | Lettuce | Radish |
| Dill | Marigolds | Nasturtiums |
Flowering
Cucumbers will start flowering anywhere from 40 to 55 days after planting. If you look closely, you will notice that your plant produces two different types of flowers.
The female flowers have a tiny unfertilized cucumber under them, while male flowers emerge directly from the stem. Typically the male flowers bloom before the female flowers, so don’t worry if you don’t initially see both types.
Cucumber flowers are bright yellow with five petals. These flowers attract many pollinators, and honeybees love them. You will definitely want some pollinators around to cross-pollinate your cucumber flowers. Once you have both male and female flowers, with pollinators flying between them, you can start looking for your first fruits!
The beginning of flowering also indicates a good time to add some fertilizer to your plants. Use organic compost or aged manure and work that in around the roots of your plant at this time.
You can also use a liquid or granular fertilizer formulated for garden vegetables. Follow the directions on the package for best results, but be careful not to over-fertilize, as this can damage your plants and fruits.
Fruiting
The fruiting stage is probably the most exciting stage thus far. You have planted seeds and watched them grow and produce their first flowers. Finally, you begin to see your first cucumber fruits. Cucumber fruits begin very tiny but grow quickly.
A fertilized female flower takes approximately 7 to 12 days to produce ripe fruit. You don’t need to do anything special during this time. Just make sure to keep your plant moist. Cucumber fruits that ripen during very dry soil conditions can be somewhat deformed but also tend to taste bitter. Keep the soil moist if you are looking forward to a nicely formed, crisp, juicy cucumber.
The most serious pest you may encounter that directly affects your fruits is the pickleworm. Pickleworm is the grub-like larvae of a night-flying moth.
The adult moth lays inconspicuous eggs on the plant, and when the egg hatches, the larvae begin to feed on the cucumber fruit from within. Signs of a pickleworm infection include: holes in your fruits, piles of white worm frass (excrement) just outside the holes, and greenish-yellow larvae burrowing in the fruits.
The best ways to combat pickleworms are by planting early-maturing varieties that ripen before these insects become active or select pest-resistant varieties. While spraying insecticides may deter adult moths from laying eggs on the vines, spraying with pesticides will harm beneficial insects and won’t have any effect on larvae already inside your fruits.
Harvest
Cucumbers typically take anywhere from 50 to 70 days after planting seeds until your first harvest. Another way to look at it is that it takes about 1 to 2 weeks after the female flowers appear for the fruits to ripen fully. Keep an eye on the cucumber fruits as you’re waiting to harvest them.
You will know when they’re ready to harvest because they will look ready. Depending on the variety, look for a mature-looking firm fruit of the approximate size indicated on your seed packet.
For most varieties, the skins will appear dark green and firm. If you wait too long, the fruits will start to turn yellow, and the seeds will be larger and tougher (unless you have lemon cucumbers which will be rounded and turn yellow to indicate they’re ready to harvest, or white cucumbers that remain a cream color).
A standard slicing cucumber will be 6 to 8 inches long, and a typical English cucumber or seedless cucumber will be quite a bit longer, around 12 to 14 inches.
Final Thoughts
Cucumbers are an excellent summer crop that anyone can grow in a sunny garden plot or as a potted patio planting. It’s quite a treat to enjoy your own home-grown summer veggies. Cucumbers can be started indoors or out and require full sun and rich, moist soil.
Keep them warm and moist during the entire growing season, and watch for any early signs of pests and diseases. Enjoy eating your cucumbers fresh from the garden, or try some unique ways to prepare them. Especially on the hottest summer days, a juicy and crunchy cucumber tastes cool and refreshing.
