Kale is one of the best vegetables to grow during winter, as exposure to a few frosts will make the nutritious green leaves sweeter and tastier. Kale can easily be grown from seed, but it’s equally as easy to plant seedlings that you’ve either grown yourself or purchased from your local garden center.
Kale seedlings should be planted out when they’re around 2 to 3 inches (5 to 8 cm) high or after the first two true leaves have developed. Space your seedlings around 12 – 18 inches (30 to 45 cm) apart to give them plenty of room to grow. Water in well once planted as this allows the roots to settle.
Here’s a step-by-step guide on how to plant kale seedlings.
Prepare The Soil
Choose a site that gets plenty of morning sun with well-draining soil. Add some matured compost, organic matter, or composted animal manures to the soil and incorporate well. Kale is quite a heavy feeder and will appreciate all this additional nutrition.
If your soil is a little on the heavy side and does not drain freely, it’s best to create some mounded rows to plant your kale in. This will improve the drainage and stop your plants from becoming waterlogged.
Kale is equally happy growing in the ground, in raised beds, or even in large containers. Remember that the plants do get quite large, so if you plant in small containers, you’ll be restricting their growth.
Choose The Right Time To Plant Your Kale Seedlings
You want to plant your kale seedlings around 6 to 8 weeks before the first frost is expected. This means that for most gardeners, planting would occur in late summer. However, for gardeners who live in Zone 8 and above, planting can continue into late fall, especially if you’re looking for a winter harvest.
This timing coincides with the notion that kale should be exposed to a few frosts in order for the plant to develop lovely, sweet leaves that are nice and tender.
If you’re planting in summer, it’s best to do this either in the early morning or late afternoon and not during the heat of the day. The tiny plants don’t need the extra stress of the burning sun if they’ve only just been planted out into the garden.
If your seedlings have been living in a greenhouse or another protected spot, it’s a good idea to provide them with a little afternoon shade for a week or two until they become well-established.
Ensure Your Seedlings Are Ready For Planting
In general, kale seedlings are ready for planting once they reach a height of around 2 to 3 inches (5 to 8 cm). In addition, you should ensure that your seedling has at least two true leaves before planting them in the ground.
To explain further, when a seed germinates, it produces two small leaves that are commonly referred to as seed leaves and, more precisely, known as cotyledons. These leaves are quite dissimilar to the normal leaves of a kale plant.
As these cotyledons are exposed to sunlight, they take on the role of photosynthesis to nourish the tiny plant as it starts to produce a root system. As the root system continues to develop, the plant will then start to produce its “true” leaves. These leaves will look completely different from the cotyledons and will resemble the normal leaves of the kale plant.
Once the true leaves have started to grow, the plant has reached enough growth and stability to endure the rigors of transplanting, and it is then safe to do so.
Planting Your Seedlings
Planting your seedlings is relatively simple as long as you remember to handle the young plants carefully to avoid any damage to both the leaves and the root system.
Firstly, you want to make a hole in the soil for each seedling that will accommodate the roots system adequately. Seedlings should be planted at the same depth as the container that they’ve been grown in.
Kale seedlings should be planted around 12 to 18 inches (30 to 45 cm) apart, as this gives the growing plant plenty of room to reach its full potential.
To plant your seedlings, take them out of the growing container or punnet and carefully place them in the prepared hole, ensuring that the roots are spread out. If there are multiple seedlings in the same container, take them all out and gently lay them on the ground.
Gently tease apart the roots to separate the seedlings. It’s not that dire if a few roots get broken at this stage because the growing plant will produce more, but try to be as careful as possible.
It’s also a good idea to handle the seedling by holding them by their cotyledons. The stems of seedlings can be quite soft and tender and easily crushed if we are not careful enough.
However, if the seedlings have been in their container for some time, the root systems may have become intertwined, and some of the roots might be quite long. In this case, tease apart the roots as carefully as you can and pinch some length off the longest roots.
The reason we do this is that, when placed in the hole, the roots are fairly straight and not kinked up or otherwise twisted. This allows the roots to grow straight down into the soil.
Once the seedlings have been placed in their respective holes, gently firm the soil around them so that they stand up nicely and are well supported.
Always Water In Your Seedlings Once Planted
Once you’ve planted your seedlings in the soil, it’s really important to water them at the soil level. Apart from providing the young plants with some moisture, this watering also helps to settle the soil around the roots, which, in turn, provides additional support.
Depending on how hot your climate is, it might be wise to water your seedlings on a daily basis until they’ve had a chance to become established. Just make sure that you don’t drown them and that any excess water can easily drain away.