Romaine Lettuce

2024-03-17 Head Formation

After having some success germinating and slowly growing buttercrunch lettuce, I decided to try my luck with some romaine lettuce seeds I bought from Botanical Interests during the summer of 2023. Luckily I had some Epic Gardening 6-celled seed starting trays ready to go that I filled with the homemade soil I talked about in the buttercrunch lettuce journal when I was planting habanada peppers for the first time.

I placed 3 seeds in each cell about 1/8" deep and watered them with a misting spray bottle, then covered them with germination domes from Epic gardening.

The romaine seedling soil also had mushrooms growing on it just like the 3/17/2024 batch of buttercrunch lettuce.

Along with the 2024-03-17 batches of habanada and buttercrunch lettuce, I’ve started hardening the seedlings by giving them a few hours outdoors. I’m gradually exposing them to sunlight by giving them indirect sunlight, increasing the time by an hour or so each day. After a few days of indirect sunlight, I will start exposing them to direct sunlight, increasing the time by an hour each day until I can leave them outside all day. I’m not taking any risks with cold temperatures at night or heavy rains, so I’ll bring them inside at night.

The seedlings were left out in the rain just like the 3/17/2024 buttercrunch lettuce.

The 3/17/2024 batch of buttercrunch lettuce. and the 3/17/2024 romaine seedlings are showing signs of stress. They are both very pale yellow, which could be a sign of being too close to the light.

I poured a small amount of organic plant for edibles from Back to the Roots that had been soaked in a cup of water on each cell in the seedling trays, just like the 2024-03-17 batch of buttercrunch lettuce.

Although lettuce can handle somewhat chilly temperatures, I’ve been bringing the seedlings inside at night because temperatures have been dropped below 40 degrees Fahrenheit. I don’t want to risk shocking the plants, especially if it rains. I’ve been bring them inside and placing them on a shelf about 18" below the grow lights.

I filled the bottom tray with water lightly fertilized with liquid fertilizer from Back to the Roots. It’s supposedly for indoor plants, but I find it easier to administer to the seedlings than their dry fertilizer for edible plants. I am going to be away this weekend, so I am filling the bottom tray enough water to last until I return.

The seedlings look great! They have a lot more green color. All of the water from the bottom tray has evaporated, but it might have been the perfect amount because the plants do not look wilted. I think the fertilizer helped a lot and now I am starting to think that the distance to the grow lights had nothing to do with the plants’ pale yellow color.

I separated the seedlings to 1 plant per cell. I buried most of the stems when I placed them into the dirt.

I moved the seedlings closer to the grow lights because it seems like they were lacking nutrients that the fertilizer provided and were not getting bleached by the light. They are not about 3" from the lights.

I started hardening-off the plants by giving them about 1.5 hours of direct sunlight.

The seedlings were given 5 hours of direct sunlight today.

The plants were left outside in direct sunlight for most the day.

The lettuce plants were left outside for about 5 hours today, but I placed them under a table for some shade because the temperature got up to 83 degrees Fahrenheit today. The plants were very wilted, but luckily I caught it early enough so I brought the plants inside. I then gave them a heavy misting and turned off the grow lights to allow them to recover.

I potted-up the lettuce heads into some 5 inch containers from Epic Gardening.

I soaked the soil and allowed the plants to sit outside in indirect sunlight.

I’m going to leave the lettuce inside for the summer because they temperature outside is too hot for them.

The plants are looking yellow so I moved the light closer, about 12 to 18 inches away from the top of the plants.

The romain lettuce heads are getting really big and they have a dark rich green color, but the edges of some leaves are becoming brown and crispy. I’m going to move the grow lights up a few inches in case they are getting burned.

The dried, crispy brown edges on the lettuce plants, known as leaf tip burmn, are actually a sign of a calcium deficiency. When lettuce grows too rapidly, there isn’t enough calcium in the soil, and very little air ciruclation, which is common for indoor plants, the it can’t efficiently transport calcium from the roots to the rest of the plant. I gave the plants a solution of azomite, which contains about 1.8% calcium, and water.

I filled the bottom trays with a lot of water because I am going out of town for a few days.

The edges of the plants and the new leaves in the center looks extra cripsy, but it looks like more leaf tip burn. Otherwise the plants looks fine and the leaves are rigid and plump, so they don’t appear underwatered.

I bought 2 Vivosun clip on fans to improve the circulation around the lettuce plants. It was difficult to set them up because of my grow light and shelf configuration, but I found a good spot above the plants where the fan can blow air on top of the plants.

My order of Cal-Mag Plus, a calcium, magnesium, and iron plant supplement, arrived a few days ago. I bought this specifically to address the leaf tip burn.

I made a solution with it and Fox Farm Big Bloom fertilizer and poured it in the bottom tray of the plants.