Cool season lettuces in green house May 6, 2021

Some of you are just beginning to grow lettuce and for some people you will be ending growing this delicious cool season crop. This year I grew in my greenhouse Cimarron romaine, Santoro butterhead, Bunte Forellenschluss, Yugoslavian Red butterhead and Italienischer oakleaf. I also grow Salanova lettuce which the mice are enjoying. (Trying to keep them out). These all do well while it is cool in spring but when it gets hot, they will bolt. I started them inside, under lights, no heat back in the end of February and yesterday it almost got to 90°F inside-way to hot for them. I’ve been harvesting them since late March and have had 4 harvests. I just harvested today (probably my last due to upcoming heat). I only put row cover on them during a predicted freeze for protection now that it appears freezing nites are over.

Lettuce bolting

What is bolting? It’s where the plant puts up a tall stalk in the center and starts to flower which is called bolting. Bolting is ok if you plan to save the seeds but if you want to eat it, pick lettuce before it bolts as the lettuce will get bitter. If you wait too long, you can compost it or if you have some chickens, feed it to them as they still love it even though it is too bitter for most people. If it has flowers, you’ve waited too long.

Harvest outer leaves and let grow back

To harvest, I take the lower outer leaves and leave the center (where they produce the leaves) intact. That way they can grow back for more harvests. The other way to harvest is cut off the whole head off which I might do when I think they are going to bolt.

Then I take it and put cold  tap water in the container with your freshly harvested lettuce and add a few ice cubes to get the water really cold and it will perk up and suck up a lot of the water.

I after rinsing it to clean and draining it, I put it in plastic baggies loosely-don’t stuff it tight and I like to wet a paper towel with cold water, fold it over several times till it makes a small square, squeeze out the excess water and put it in the bag that you’ve closed up tight and in the crisper-it lasts much longer. The night before I want to harvest, I water the lettuce well and I harvest it EARLY in the morning the next day before the heat sets in. Never harvest when it is hot or it will be wilted and you will be disappointed. All of this applies to spinach and arugula as well.

If you’ve already planted lettuce or are just starting outside from seed, you should put row cover right on top of it to provide shade and keep out rodents, which also love it. Row cover at night will also add protection from any late freezes we get. I use a medium weight row cover (also called Agribon) about .5 mil in thickness with 85% light transmission. No winter weight row cover (.9 to 1.2mil) now which would not provide enough light and would hold in too much heat for the plants. You want rain (HA!) and air to get thru it and you can water right thru it too. To keep rodents out, I lay 2×4 boards all around the edges of the row cover to secure it from wind and rodents. And definitely plant in a shady part of your garden now for sure or make your own shade as mentioned above.

So is lettuce season coming to an end yet? Well, yes and no. The cool season lettuces will definitely be finishing up soon as it gets hotter but there are varieties of SUMMER LETTUCE that you can plant that will resist bolting if grown under shade. These are called Batavian or Summer Crisp lettuces. Look these up on the internet for varieties you can buy and where. I will write about them and how they do here in the summer and what varieties I have tried in the next post. Stayed tuned…