Speedy seeds, bypassing bolting bitterness and opinions on overburdened oranges
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Lettuce know the secret to summer leaves
What’s the key to growing lettuces in summer? I can never get it right. They start out looking lovely, but as soon as I begin harvesting, the plants bolt and the leaves become bitter and horrible. I don’t have this much trouble in winter.
Levi N, Mt Eliza, Victoria
I’ve struggled with the same problem. Growing lettuces in winter is easy. But when you want them for summer salads, perversely it’s so difficult to grow them. There are two main factors at play here:
Increasing daylength induces the plants to bolt via a mechanism called photoperiodism.
Stress, in the form of heat or drought, can cause the plants to “panic” and begin to reproduce (i.e. bolt).
To grow nice lettuces in summer, you’ll need to stop the days from lengthening, keep the temperature mild and water the plants often. Only one of those is within your control, but planting lettuces in partial shade might help reduce the heat and drought stress that they experience.
A workaround technique you can try is succession planting. It’s tricky to get right, but it will pay big dividends when you do. The idea is that rather than planting one huge crop of lettuce, you plant a few plants every few weeks. As each crop begins to bolt, the next crop should be ready to start harvesting.
I’m still working on the specific timing between successively planted lettuce crops, and I expect that it might vary depending on the time of the year. Behind the scenes, I’m quietly running a big experiment to optimise planting strategies. At the start of every month, I’m sowing lettuce seeds in the greenhouse. When the seedlings are big enough, I’m transplanting them into the garden. As usual, I’m recording lots of data, such as:
time to germination
lead time to transplant
harvest start date
date I first notice bolting.
This will let me optimise the timing of each crop. I’m doing the same thing for other leafy greens, such as kale, mustard greens, bok choi and even celery.
I’m about halfway through the experiment. Initial results vary wildly between the types of crops but around six weeks between successive lettuce crops could work well for continuous summer picking. I’ll be announcing the results from the trial next winter and will be using them to inform the how to grow guides that I’ll write for the various leafy greens. Stay tuned!
Soaking seeds for speedy sprouts?
I’ve read that prior to planting certain vegetables such as beans and peas they can be soaked in water overnight to enhance germination. What’s your take on this?
Geetha S, Torquay, Victoria