You may have planted cucumber seeds indoors to try and get a headstart in the growing season, only to find them falling over in a few weeks. Try as you might, you can get the stems to stand or support the weight of the seedlings. So the question lies, ‘why are my cucumber seedlings falling over?’
Why Are My Cucumber Seedlings Weak and Floppy?
The reason why your cucumber seedlings can’t support themselves and are falling is probably due to a lack of light. It’s a common problem gardeners have experienced for years and is known as having ‘leggy seedlings’.
The characteristics of a leggy seedling are more or less the same- the stem is unusually tall (seemingly outstretched) but it’s very thin or narrow. Instead of growing upright, a leggy cucumber seedling will twist and turn towards a source of light (usually a window).
Leggy cucumber seedlings are a sign that your young plants need more light. In general, seedlings will need at least 10 to 12 hours of bright light in order to grow well.
If not, they will experience stunted growth and are likely to stretch themselves thin. When this happens, your seedlings tend to fall over to the soil or ground.
Seedlings that don’t get enough light will expend their energy to grow up and towards an adequate source. They will sacrifice stem thickness for length, and over time the seedlings will not be able to support themselves. Unless you provide more light then your seedlings may not be able to make the transplant, and you’ll likely have to start over.
Other reasons why your cucumber seedlings fall over include damping off (due to bacteria in the soil) and waterlogged soil due to overwatering.
Can I Fix Leggy Cucumber Seedlings?
The good news is that you can fix leggy cucumber seedlings that are starting to fall over. The sooner you can catch it, the better so your current batch can transition from seedling to mature cucumbers in a single growing season.
Once you notice your cucumber seedlings getting leggy, immediately reposition them so the plants get more light. A south-facing window will serve as the best spot indoors, but if you can’t then you’ll need to supplement with grow lights or fluorescent tubes.
To try and help thicken the stem you can put a small oscillating fan and set it to the lowest power to recreate natural wind. This forces the seedlings to put some of their energy into not falling over as a result.
How to Prevent Cucumber Seedlings From Falling Over
More Light, Less Leggy
Cucumber plants are warm-season varieties that thrive under full sun. Anything less will cause them to stretch out and elongate instead of growing new leaves and fruit.
The key to preventing the seedlings from falling over is to provide adequate light. This can be in the form of natural and indirect sunlight outside, through a window or a grow light if you’ve planted the seeds indoors and the weather is too cold.
A south-facing window should be enough light, but you can supplement with a grow light if the days are too short. The correct distance to put a grow light is about 2 to 4 inches directly above the seedlings for fluorescents and LED products. Adjust the distance as the cucumber plant grows and as long as you’re growing them indoors.
A good rule of thumb is to provide anywhere between 8 to 12 hours of bright light so your seedlings won’t get leggy and fall over.
Use a Fan
An oscillating fan is an excellent way to toughen up your cucumber seedlings and prepare them for outside wind conditions. Keep in mind though, that using a fan is only second to giving your seedlings enough light to prevent them from getting leggy.
A small fan that can oscillate back and forth should suffice. The breeze should be enough that the plants sway with it, but not too strong that they fall over. Turn on the fan for two to three hours each day and during the seedling phase, and soon you’ll notice the stems getting thicker.
Alternatively, you can lightly brush your cucumber seedlings several times a day to achieve the same effect.
Related article: Every Reason Why Tomato Seedlings Are Leggy