Cucumber plants are vigorous annual climbing vines that are easy to grow. They take up little space in the garden because they fare best when staked to a trellis or a fence, so they’re a great option for compact spaces.
Although cucumber plants grow vertically when trained, they do need quite substantial pots to accommodate their extensive root systems. Here we look at the pot sizes you should be used for growing cucumber plants.
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Pots for Sowing Cucumbers
Cucumber plants are not frost-hardy, so in climates outside of USDA hardiness zones 9 to 11, the seeds of these plants should be sown indoors. Since most people don’t have an abundance of space for growing plants in their homes, small pots work best for sowing cucumber seeds.
Choose a pot that is 4 to 6 inches in diameter for a single cucumber seed. The pot should be filled with good-quality potting soil, which is rich in organic content. Plant the seed at a depth of around half an inch, ensuring it is lying on its side. The small pot containing a cucumber seed can be stored on a warm windowsill in the house or in a heated greenhouse from early March.
If you are sowing the seeds in an unheated greenhouse, you can do so in a small pot from the middle of April. If you intend to sow the seeds outdoors, you can use a larger pot from the start, ensuring that any chance of frost has passed.
Most cucumber plants that are sown outside should not be planted until late April since they are very sensitive to low temperatures, ideally being placed in soil that is between 75 and 85 degrees Fahrenheit.
Pots for Cucumber Seedlings
After sowing your cucumber seeds, they should begin germinating, and a sprout will develop above the surface of the soil for around 7 to 10 days. The seedlings can remain in their original small pots until they are around three weeks old.
After this time, they will then need to be moved to larger pots to allow their root systems to expand and become big enough to reward you with a generous bounty of flowers and fruits. Keep the small cucumber pots indoors in a warm environment or a heated greenhouse until around late April or early May, when the weather is consistently warm.
Pots for Flowering and Fruiting Cucumbers
Once the cucumber seedlings are 3 or 4 weeks old, they will need to be transplanted from their small original pots to their larger, permanent pots. A single cucumber plant will need to be grown in a pot with a capacity of at least 5 gallons. This will allow the plant enough space to spread its roots and provide enough moisture and nutrition to help the plant thrive.
If you have the space, a pot that is bigger than 5 gallons will also be suitable for a single cucumber plant. Avoid growing multiple plants in a single container unless it has a significant soil capacity because the roots will compete against each other for nutrients, water, and space. If you wish to grow two cucumber plants in a single container, the pot will need to have a capacity of at least 10 gallons.
Best Soil for Cucumber Pots
Cucumber plants love well-draining soils that are high in organic content. A good quality compost potting soil will be ideal, or any rich, loamy potting soil.
The soil will need to be kept moist but not wet. Avoid overwatering the cucumber plant as this can cause root rot, but equally, these plants are not drought tolerant and will quickly die without adequate moisture.
How Big is a 5 Gallon Pot?
Gardening guides commonly advise on the volume size of a pot for certain plants; for example, it’s common that a cucumber plant is recommended to be grown in a 5-gallon container. But how big is a 5-gallon container?
In terms of typical plant pots, a pot that has a diameter of 12 inches and a height of roughly 10 inches will have a volume of around 5 gallons. This means that this will be the ideal pot size to grow an adult cucumber plant in. Since cucumber plants are annuals that only last a single season, you can grow a cucumber plant in a 12-inch diameter pot for its entire life cycle if you have enough space.
There is no need to start the cucumber seed out in a smaller pot unless there is a space issue that prevents this. Commonly people who want to start their cucumber plants indoors will use smaller pots because these take up less space on a kitchen windowsill, and they can be transplanted into bigger pots when the plants are able to be moved outside.
How Big is a 10 Gallon Pot?
If you want to grow two cucumber plants in a single pot, then the pot will need to have a volume of at least 10 gallons. A 10-gallon pot can come in a number of sizes, and any of these will work. A round pot that is 16 inches wide and 15 inches deep will have a capacity of 5 gallons, and a round pot that is 18 inches wide and 12 inches deep will also have a similar capacity.
When multiple cucumber plants are grown in a single pot, the vines will become entangled and grow to form the look of one very large, lush cucumber vine. This is absolutely normal, and you do not need to try to keep the plants separate from one another.
Can Cucumber Plants be Grown in the Ground?
Using pots or grow bags is ideal for growing cucumber plants, especially if you need to start the germination process indoors. However, in USDA hardiness zones 9 to 11 these plants can be sown outside, in which case you may find it easier to simply plant the seeds directly in the ground.
There is no reason that cucumber plants cannot be grown in the ground; it is simply a matter of preference. Whether your cucumber plants are grown in the ground or in a container, you will need to stake the vines so that they do not grow along the ground.
Staking Cucumber Vines in Pots
Cucumber vines that are growing in pots will need to be staked at the earliest opportunity so that they climb up a wooden trellis or fence.
You can position the pots up against a wall or fence and encourage the vines to climb up the structure, or you can insert stakes directly into the pots so that the vines can grow in a more freestanding manner. Cucumber vines grow vigorously and if grown along the ground, are vulnerable to disease and rot.
This is why they need to be secured to a stake or trellis, where they won’t come into contact with moisture and will have better airflow. Alternatively, you can grow cucumber vines in hanging baskets so that they can trail downwards. This is the only instance where cucumber plants will not need to be staked or trained in a climbing manner.