Taking full advantage of our cool seasons, lettuce seed can be sown in fall or early winter with an alternative round of seed sowing in February and/or March. Days to harvest from seed can be as long as 70 days and as short as 35 with our climate driving the calendar as we strive for better taste before bolting or bitterness. True annuals, lettuce and many greens are cool season plants, their trigger to complete the cycle arrives with longer days and warmer temperatures.
A cold frame is the best way to grow some of the smaller head types which require the longest days to harvest. But I must add that vast improvements have occurred in the last 20 years most notably the inclusion of dwarf types or dwarf head lettuce which allows us to grow varieties that used to grow poorly with our short spring season.
There are about 7 types of lettuce varieties with hybrids between head lettuce and looseleaf. The beauty of looseleaf types or a mix of tender greens is the ability to cut them as they grow, harvesting over a long period. As days lengthen, a hint of bitterness will be evident but I have found that an afternoon in the fridge will improve the taste. A list of the various types follows and I have included some of my favorites. Nasturtium leaves can be added for a peppery taste, viola flowers for their beauty and health benefits (vitamin C), and red mustard if you like it spicy.
Listing types from the longest to harvest to shortest, as you might imagine the head types take longer. The most common head lettuce requires 60 to 70 days to harvest and was developed for long distance shipping. Inferior in taste when compared to others, these are called the crisphead or iceberg types. With their prolonged growing requirements they are poorly suited for growing here.
The Batavian, also known as French or summer crisp are intermediate between butterhead and crisphead. Loose heads form with a harvest time of 50 to 60 days from seed. My favorites for slow to bolt or heat resistance are 'Nevada' and 'Muir'.
The butterhead types include Boston lettuce. Small, dense heads ripen in 50 to 60 days. The flavor is light and delicate with red leaf types such as 'Red Butter' and 'Red Oakleaf'.
Bibb lettuce is heat tolerant, the most popular variety has been 'Buttercrunch' which requires 55 to 70 days to harvest. New dwarf types can be harvested in as little as 40 days, adorable with their small compact size and ideal for our climate. I recommend 'Little Gem' and 'Rosaine'.
Leaf types are also known as looseleaf or cutting lettuce. Very successful March sowing will give you some gorgeous leaf types. Harvest time for a full head (loosely speaking) is 50 to 58 days but harvesting can begin when the leaves are small. I even like to mix these into the garden beds or mixed containers. There are many to choose from with varying colors of bright green, to a pinky green with 'Vulcan', to bronzy reds with 'Ruby Sky'.
Oak leaf lettuce has a distinctive leaf which is beautiful in a salad. New dwarf varieties can be harvest in less than 50 days, forming very loose heads of bright green or dark burgundy. 'Galactic' was always my favorite but has been superseded by a hybrid of similar red color known as 'Rouxai'.
Romaine or cos types in their standard (large) size require 60 to 65 days to harvest. New mini romaine is definitely best for us with compact leaves and maturing in as little as 43 days, resistant to bolting which equates to better taste over a longer period. I recommend 'Dragoon' with a 43 day harvest.
Mixed greens or baby leaf blends are popular. Each mix is developed for early harvesting, a mix of colorful leaves, and/or spicy greens such as mustard, arugula, spicy cress, and mizuna. This is a good option for long harvest because some will bolt earlier while others continue to produce.
A cold frame is recommended but there are alternatives. The over-wintering fabrics work incredibly well for us. Small hoops can be placed to essentially create small tunnels, but truth be told just laying a layer or two of the fabric over your plants is enough to protect them from super high and low temperatures. The fabric can be rolled up on sunny days to warm the soil which protects them on super cold nights.
Lettuce seed requires light to germinate so sow seed directly on top of the soil. A sprinkling of vermiculite may help keep seed in place with no hindrance in germination. If you are concerned with contaminated soil where weeds will sprout, add a thick layer of compost down first and sow seed directly on top.
Once your lettuce crop is finished it will be time to plant tomatoes, beans, and peppers in their place.
