I'm growing leafy greens early this year. For example the lettuce variety Lollo Bionda, parsley plus a mix of different seeds for my hotbed. Photo: Ida Sjöö.

There's just something special about taking the first new plants of the year to the garden. They almost seem infused with the anticipation and dreams about the new season. This bright, crisp green color definitely does something to me! I just need to finish my latest book about sustainable gardening, get away from the desk and go straight into the garden. I'm actually surprisingly low on new seedlings after the winter! I wanted to restrict myself a little this time and focus on balance. By now, I have all the plants in the hotbed outside and suddenly got more space indoors. Time to grow leafy greens and new little seedlings!

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This post is about the vegetables that I prepared for my hotbed: leafy greens in a plug tray. Remember that you can use these types of plants for much more than just hotbeds. If you sow now, then you have plenty of seedlings that you can take to the greenhouse, put in sheltered spots in the beds outdoors, growing frames or pots later in spring. You might need to wait a few more weeks if you live further north than I do of course. But how do you go about growing leafy greens then? Keep reading to find out!

I sowed the leafy greens for my hotbed already in January. I have fifteen different varieties here, growing indoors under a grow light without getting used to the outside temperatures first. Photo: Ida Sjöö.

Plug Tray with 150 Cells

This is what we usually call a plug tray or seedling tray. This QuickPot one has 150 connected little cells. QuickPot is a German company that uses recycled plastic and sustainable energy to create their trays. The plug trays are very durable too and can last up to ten years.

The large 150-celled tray is my favorite one. I use it to grow lettuce, onion, cabbage, asparagus, chard and much more. I think I have six or seven of these by now. This is my favorite way to grow plenty of little seedlings in a smaller space, which is extremely valuable in my garden!

These plug trays also come with a little contraption that helps me push the seedling plugs out. It's simply put a tray covered with spikes, one spike for each cell in the plug tray.

The plant with red/purple leaves is actually a bok choy. I think it's called Lady Choi (Baker Creek Heirloom Seeds.) Unfortunately, all my bok choy plants unfortunately bolted when the transplanting got delayed. Photo: Ida Sjöö.

One of my favorite plants last year, the Frillice lettuce variety. Photo: Ida Sjöö.

Fifteen Varieties

I'm growing leafy greens of fifteen varieties in this plug tray, with ten plugs for each variety. This is such a great way to get a nice mix of seedlings. Here are the leafy greens I decided to grow here:

• dill
• spinach
• Frillice iceberg lettuce
• Little Gem lettuce 
• black kale
• Giant Winter spinach (didn't germinate)
• leek
• Lady Choi bok choy
• Color Crunch Blend bok choy
• Bonsai bok choy
• komatsuna
• Chinese broccoli
• Siberian kale
• arugula
• napa cabbage (only one seed germinated)

I also prepared seedlings of Italian parsley that I sowed in December, and the Lollo Bionda lettuce variety.

One of the many bok choy plants that bolted when growing leafy greens. They don't want to stay in a plug tray or pot too long, especially not with a grow light on top. Photo: Ida Sjöö.

Bolting Bok Choy

The transplanting project was a few weeks delayed. Mostly because the construction work on the hotbed took longer than expected, and then I had to wait another week for warmer weather outside. Then of course, my bok choy bolted while I waited. I'm not happy about it! But I guess it is what it is.

Bok choy is a so-called short-day plant. If it gets stressed or too much sun, then it almost immediately bolts. Bok choy is the perfect plant for a hotbed since it grows so quickly. But of course, the timing needs to be there. I didn't get it right this time.

Alright! The lovely new plants are getting settled in the hotbed. We actually had a drop in temperature, 14 degrees (-10 degrees Celsius) the night after I planted them. I'm so happy that I covered my plants with a thick layer of straw and blankets before it happened!!

New Seeds

I decided to sow a bunch of new seeds in the hotbed too. For example spinach, thyme, arugula, bok choy and a few other things. The seedlings I planted here will be done first. I hope that the new sowings won't be too far behind though!

This is what the plugs look like after you get them out of the tray. This Iceberg lettuce variety looks more like a leaf lettuce but with the perfectly crispy Iceberg texture. I actually haven't tried growing Iceberg in a hotbed before since it can be a bit sensitive to the cold. I'm crossing my fingers! Growing leafy greens can be risky! Photo: Ida Sjöö.

Three growing frames with soil, ready for sowing and planting. Each frame comes with a lid too. Photo: Ida Sjöö.

The leafy green komatsuna on the right and Chinese broccoli next to it. Photo: Ida Sjöö.

The leek got a bit smothered by the surrounding plants. I sowed the leek in clusters and was planning on growing it like chives. I want to plant the leek in the kitchen garden later. Photo: Ida Sjöö.

Look how nice it looks after planting! I put a lid on top of the plants during the day and then I add a layer of blankets and covers to keep the bed warm at night. Photo: Ida Sjöö.

Grow Leafy Greens Early

I definitely recommend using a plug tray with smaller cells if you want to try growing leafy greens early this year. These plants actually prefer smaller cells and might not do as well in a larger space. The leafy green root systems are small, so don't worry about cramming them in there!

A plug tray with 150 or around 100 cells should be enough, but you can of course get a smaller tray too if you prefer that.

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Use one row per vegetable and fill the entire tray. My idea is to grow an entire bowl of salad every time I sow, so I want to get a nice mix of different leaves. Let your taste buds decide what goes in your tray!

I'm going to talk more about the hotbed soon. Perhaps a fun springtime video with the first harvest of the season?

Do you want to know more about growing leafy greens early in your garden, on your balcony, the windowsill or outside in the greenhouse? Check out the links below to find out more!

How to grow bok choy microgreens
Grow microgreens at home
How to use a plug tray
Guide to growing pea shoots indoors
Beets from seed in a plug tray

Good luck growing leafy greens this spring!
/Sara Bäckmo

PS. I have a fun new project in the pipeline this spring which is why my colleague Ida Sjöö helps me take pictures for the blog. She took all the pictures for this post. Don't forget to press/hoover over the pictures to read the captions.