Saturday, June 12, 2021
I love salads! Eating fresh greens every day is healthy. Having them in the summer is refreshing. Unfortunately, lettuce and spinach are cool season lovers and quickly bolt in the heat of summer. You do have ways of keeping the summer salads going, though! Here are the tricks I have learned over the past few years.
Before we get into the details of tricks to keep the harvest going, let me talk about the term "bolting". When it gets hot, it signals to the plant that it is time to make seeds. Lettuce, spinach, and most greens do this by sending up a stalk that then produces flowers and seeds. Lettuce has 3 foot tall stalks with tiny yellow or blue flowers, depending on the variety. When lettuce starts to bolt, most varieties get bitter tasting. So, you want to keep your plants from bolting, and thus giving you sweet leaves for eating, as long as possible.
Growing Conditions
Now that you know the conditions that causes lettuce to bolt, you want to give them the conditions that keep that from happening as long as possible. Lettuce thrives in cool weather and moist soil. I use self watering pots called Earthboxes, but any self-watering pot will do, for more consistent soil moisture. You can also use a regular pot with a big catch pan. You just want the soil to not dry out between waterings.
Moving your pots to a shady part of the yard and the north side will keep the plants cooler, too. If you are planting in the garden bed, use the same strategy, plant on the north side, in a shadier spot or by larger plants that will provide shade. I am trying a shade cloth placed on the sunny side of my small portable greenhouse frame this summer to see if it helps the plants last longer before they bolt.
In addition to moist soil and cool temperatures, greens love nitrogen. Be sure to fertilize them monthly if using a solid fertilizer or biweekly if using a liquid fertilizer. For liquid fertilizer, I alternate between fish emulsion and liquid seaweed. Since I eat greens daily, I also add kelp meal or Azomite annually to get a wide range of minerals into the soil and plant. You are what you eat!
Varieties of Greens
There are many varieties of lettuce that are bred to be more heat tolerant than others. There are also varieties that even when they bolt, their leaves remain sweet tasting. Look for varieties that say things like "heat tolerant", "bolt resistant", or ones that were developed in hotter regions. Summer varieties that I grow are New Red Fire, Simpson Elite, Optima, Jericho, Green Towers, Red Sails, Royal Oakleaf, Butter King and Bronze Beauty. I am trying a few new ones that I just sowed last week. They are Giant Blue Feather, Buttercrunch, Calmar, Green Ice, Cimmaron, Deer Tongue, Little Gem, and Yedikule. A couple others that have tested well for summer heat are Magenta and Nevada.
There are other greens that are great in salad that love the heat. I always grow Sprouting Broccoli (leaves do taste like broccoli plus you get baby broccoli florets), cultivated dandelions, white ribbed chard varieties like Fordhook, Red Malabar Spinach, New Zealand spinach, orach and amaranth.
Succession Planting
No matter how hard you try, nature will have its way and your lettuce and spinach will bolt. Succession planting is the answer to keep the lettuce going. I have pretty much given up on having summer spinach. Red Malabar and New Zealand spinach are such great substitutes in salads and grow prolifically in the heat that I harvest from them all summer.
For lettuce, re-sow every 3 weeks to have new plants ready when the last round starts to bolt. You'll have to play with how many to start based on how much lettuce you are using each week. I always have intentions of re-sowing every 3 weeks but for me it is usually every 5-6 weeks. I want 8 plants to reach full size from each sowing.
Pests
Slugs are the biggest pest for lettuce if you are keeping the soil moist. Slugs love moist places! You have a few options for keeping the slugs away. You can scatter egg shells on the soil surface, surround your plants with copper, place coffee grounds around your plants (gives nitrogen to your plants, too), use a homemade slug trap of beer in a container buried in the soil or use a slug bait. The watch out with slug bait is it can cause issues if birds eat it so put it out in the evening after the birds have gone to roost.
Seed Saving
I save seeds from the lettuce plants that do the best. Lettuce is self-fertile so their seeds should give you the same plant as the mother plant was. You can also just let the seeds go where they like and then dig up the new plants as they sprout to put them where you want them.
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| Lettuce bolting with flower buds |
Lettuce seeds do not germinate well in soil temperatures above 70F and not at all above 85F. This can be a challenge in pots in the sun. I sow my seeds in shallow pots on the covered patio. During extreme heat, you can start them indoors. To plant your seeds, make sure the soil is moist, sow the seeds on top of the soil and then cover very lightly. Lettuce seed requires sunlight to sprout so you don't want to bury them under the soil. The seeds should germinate in 7-10 days. You want the soil to be moist but not wet. Waterlogged seeds will rot. Be sure to harden them off before planting into a pot or the garden. You want to ease them into the strength of the summer sun and heat.
If you want to try homemade dressing, here are a few to try with herbs from the garden: Homemade salad dressing recipes with garden herbs
Now you are ready for salads all summer long!
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