Last year I switched growing my greens from the community garden to the back deck of the boat. I had thought that having lettuce at a nearby garden would be close enough for regular harvests. But, I found out that even on a short drive, my lettuce would droop, losing its crispness.
Due to its shallow root system, lettuce can be a great plant for containers. Raising it off the ground can also make the plant less accessible to slugs. On the back deck, the lettuce seemed to do well. It grew straight and tall in one of those long oval boxes that are meant to be put over a deck rail or happily for me, over my boat’s back rail.
I’d harvest using my thumb and forefinger to prevent pulling out the roots and pinching off the biggest leaves about an inch off the base as I would kale. Sometimes I’d snip a third of the plant off and let it come back in the way I harvest parsley. By the time I’d harvested enough for a salad, the container would look savaged. However, in a day or two, it would recover and although it took longer to be full and lush, it regained some dignity.
In a two-week cycle, I would continue to either harvest the bigger leaves or cut another third. By the time I had harvested the last third, the first cuttings would have grown sufficiently to be ready for harvest again.
This year, I’ve added three more boxes, which unfortunately do not all fit on my back railing. I found that only having one box last year wasn’t enough to supply me with greens for the week. I’ve planted loose leafed lettuce; two containers of Black Seeded Simpson and one of Oakleaf. The other container is where I keep trying to grow spinach and arugula. I might switch and try either the red or green variety of Deer Tongue next year.
Like all plants in a container, lettuce needs to be watered much more than direct sown plants. I find that I water at least every other day. When the sun heats up the back deck, the lettuce clutches for life like someone crawling on desert sand looking for water. On some days I water twice because they do better with smaller amounts of water than a thorough soaking. The shallow roots can only take in so much water at a time.
In addition to needing a lot of water, lettuce is also a heavy feeder of soil nutrients. I fertilize the greens every other week. Fertilizers are geared to the three biggest things plants need: nitrogen, phosphorus and potassium and are expressed in the ratio N:P:K. Tomatoes need a ratio of 5:10:5 whereas lettuce does well with 5:5:5 or 10:10:10.
I use a water soluable fertilizer in my containers. I’m careful to dilute it to the right mixture. Fertilizers are essentially salt and plants, like people, tend to better with less salt.
My back deck has a nice border of leafy greens and I’m finding that we rarely buy lettuce from the store this time of year. If only I could figure out how to create just a little more space, we wouldn’t need to ever buy it.
• Corinne Conlon is a freelance writer based out of Juneau. She can be reached at dirtgirlgardening@gmail.com.
