Cultivating organic lettuce all year round indoors or outdoors is possible?

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Growing lettuce punctually in the spring or summer does not pose any particular problem: they tolerate not having a lot of light , prefer to have a fresh soil , and it stops there. Except that if you want to eat all year , it becomes another pair of sleeves. In this case it is necessary to have varieties adapted to each season , and to be able to spread out its seedlings in the time . This article offers some clarification on the subject.

NB do not be surprised if we do not talk about spinach, lamb’s lettuce or chicory in this article: they are used to make salads, but they are different species.

Did you know ?

Lettuces are plants of the genus Lactuca and the family Asteraceae . You’re not told that to be an expert, but because it’s also the family of daisies , asters , Jerusalem artichokes , rudbeckias , thistles , dandelions – in short, flowers that are easy to grow on heavy soils. in broad daylight.

Wikipedia is very clear on the different categories of lettuce varieties, if you want clarification it is here .

What do lettuce need?

To consume lettuce, it is sufficient that it reaches the leaf stage – unlike fruit vegetables – which requires relatively little energy. No need for particularly rich terrain, or a super-mild climate. 
Salads are grown in the sun or partial shade in ordinary soil. The only “thing” is that if they have a lot of sun and little water , they will ”  go to seed “, that is to say use all their energy to make flowers. Same if you drag too much to harvest them. 
Once they have received this signal that encourages them to produce seeds, you can always prune the flower stems to slow them down. This is not very effective, however, and do not wait to eat them.

Water management for beautiful lettuce.

This is the nerve of war. During the six weeks of cultivation, there is no need for water , otherwise lettuce will make leathery leaves .

In the wild, lettuce is enjoyed in rather dry ground, in full sun. Except that to consume them, one wants to force them to make large leaves, and no stem, not to “go up” what. Compared to their “ideal” conditions, the gardener “provides” them with less light and more water .

We can of course mulch , but it involves managing invertebrates – understand mollusks – at certain times – in early spring and late summer. A trick that works pretty well is to interpose lines of garlic, onions and shallots. Some innocent people may think that their smell would repel molluscs? Unfortunately no, it works because the smell of garlic hides lettuce, so mollusks will not feel at a distance. Because, it will not deceive those who pass by by chance.

The soil must never dry to the point of forming a crust , between two waterings we can however wait until let the surface dry very slightly . This implies to vary enormously the rhythm of watering according to the season: once a day in summer and never in winter.

Which varieties for which season?

To harvest in the spring.

All varieties of lettuce can be sown early in the spring to be harvested as early as April. It can even be sown at the end of winter under a frame before transplanting.

To harvest in summer.

Summer varieties are called “open field”, such as batavias, or “fat lettuce” such as sucrine or redness. You can also grow “cut” salads like oak leaves at this time.

To harvest in winter.

All lettuce can not stand the winter cold. Oak leaf lettuce, ‘Salad Bowl’ lettuce, ‘Winter Wonder’, and ‘Apia’ head lettuce – among others – stand up well to the cold. Beware, some so-called varieties are called winter because they support the lack of light, but not the cold, so they must be sheltered.

Make a calendar / spread out his seedlings.

Depending on the season, plan between 6 and 10 weeks of cultivation. The more intense the sun, the less you can cultivate for a long time, and the more it will be necessary to sow often.

In March : Start in the early spring by sowing a variety to cut, to ensure the blow. Of course, you should also sow a second variety that you will choose exclusively for its flavor. In the spring, do a monthly sowing session, and you will never be short. 
From mid-May , you have to adapt the varieties you sow, because some of them do not tolerate drought. We recommend thick fat lettuce and head lettuce like ‘Batavia’. Go to a planting rate every 21 days. 
From September onwardsyou can start sowing the winter varieties, those with tough leaves and do not fear the cold. A sowing every 40 days is enough, especially if you have varieties “to cut”.

Spray, or sow in place?

To sow under shelter and to transplant then is not automatic , it is interesting especially at the beginning of the spring and in winter, so that the seeds have enough hot and germinate. When you transplant, do not forget to cut the leaves in half , so that your plants will dry less the first days. If you see them all withered the first days do not panic, that’s normal it’s the time it takes them to re-root.

Make salads inside?

It’s a good idea, it just takes a little space. Basically, we get the equivalent of a lettuce per 3 L pot , so if you want to eat often it quickly becomes cumbersome. Other than that, if you have a well-exposed window it’s enough as light.

There is no complicated gesture to make: it is enough to sow not too dense in a rather fine mixture, to cover barely ground. As soon as the feet have 4 leaves – 2 cotyledons and 2 leaves – lighten to keep only the most beautiful every 10 cm. Nothing prevents you to transplant the surplus into other pots.

The temperature of the apartments not overheated – 17 to 21 ° C – is suitable for lettuce, although ideally they should have a little cool at night. Moisture level is like outside, it is necessary to water in fine rain only when the soil dries on the surface.

Count at least 4 weeks of culture.

Should one fertilize one’s lettuce?

As explained above, lettuce has only leaves to produce, so they should not be demanding in fertilizer. We find it particularly silly to put mineral fertilizers on a plant that does not really need it. 
On the other hand if you have a compost, use the compost tea well diluted once every 3 weeks, it will help the leaves to grow. Do not put on the leaves, just mix with the water.

Dr. Kimberly Seltzer

Postdoctoral Scholar, UC Berkeley Research Assistant, MIT

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