There are two big groups of lettuce (Lactuca Sativa) farming in Indonesia: leafy lettuce with rounded loose head with green flaring leaves and heading lettuce with rounded or oval packed solid head. Between those two options, the most popular in Indonesia is the leafy, curly ones or as we’ll call it here, curly lettuce. Curly lettuce is quite tolerant to be planted in tropical or even hotter area. Curly lettuce can even grow well in hot and lowland like Jakarta.
Basically, the optimum temperature for curly lettuce farming is around 15-25 degree celcius on 900-1200 meter above sea level land. The preferred soil types are dusty clay, sandy clay, and humus-filled soil. However, curly lettuce will grow anyway in low nutrient soil if you plan your watering and organic fertilization correctly.
Seed choosing and sowing
Lettuce reproduces generatively with seeds. You get the seeds from previous harvest after your lettuce crop has produced fruits that are old enough, and get the seeds out. If you buy your seeds from the shop, the most popular varieties these days are the penn great lakes, imperial, and new York. You will need 250 gram of seeds per hectare. For optimum result, it’s better to sow your seeds first before your plant them on the ground directly.
There are some suitable sowing medias for lettuce farming like polybags, banana leaves, tray system, or molded soil, or seedbeds. In this article, we’ll see about sowing on seedbeds.
Prepare your seedbed that is 1 meter in width and 15 cm in height, with length as needed. Your seedbed should be in the open area and away from animals that might disturb it. Mix manure fertilizer, soil, and husk charcoal with 1 to 1 to 1 ratio. Make sure to use ripe manure fertilizer to avoid growth of unwanted microorganisms. Manure fertilizer is useful in providing additional nutrients. Husk charcoal will be needed to keep your soil loose and your lettuce roots intact when they’re pulled out. The ideal acidity for your soil should be between pH 5 – pH 6.8, so if your soil is too acidic, add some agricultural chalk or dolomite as needed.
Water your sowing media with clean water to give your seeds enough humidity. Pay attention to how much water you use; make sure not to use too much that it forms puddles. Scatter your lettuce seeds uniformly onto your seedbed. You should use 100 grams of seeds per 10 square meter of seedbed. If sowing happens in the dry season, it’ll be better if you add mulch from grass, straws, or dried leaves on top to lessen evaporation due to the heat of the sun.
Make shade or shelter over your seedbed. This will be useful in the rainy season to protect your seedlings from direct hit of rain and in the dry season to protect your seedlings from overexposure of the sun. Your shade could be made of paranet, plastic sack, or transparent plastic. Adjustable shade is preferable to control the amount of sun your seedlings will get on certain times of the day. At this stage, the care you can do is simply watering, weeding, and pest and disease control.
Organic curly lettuce farming doesn’t allow the use of synthetic pesticides. Get rid of pests using cover, get rid of diseases using more manure fertilizer or phytopesticides. Your seedlings can be moved after you can see 4-5 leaves or 3-4 weeks after sowing.
Soil processing and seed planting
Soil processing in curly lettuce farming depends on the type, structure, and texture of the soil. If your soil is very hard, pay more attention in harrowing first and foremost. After that, you can form your seedbeds that are 1 meter wide and 15 cm high with the length about 10 meters or so depends on your land condition. To keep your seedbeds dry especially in wet lands like rice field and stuff, your seedbed’s height could be up to 20 cm with drainage system on its left and right. Your seedbed cannot be too wide.
Curly lettuce farming needs almost neutral acidity which is between pH 5-6.8. If your soil is too acidic, add chalk into it. If it’s not acidic enough, add sulfur or gypsum into it. For example, to neutralize pH 5.5 soil, you need 0.1 kg of chalk per square meter so your soil will reach pH 6.5. On the other hand, to neutralize too high of pH, you can use 0.6 kg of sulfur or gypsum per square meter.
To increase the amount of nutrients and humus in the soil, add some manure fertilizer or compost into your soil mix. The recommended amount of manure fertilizer is 20 tons per hectare. If you use compost, the recommended amount is 2 kg per square meter. Organic fertilization is done to keep your soil fertile and to heighten microorganism activities in the soil. After you mix your fertilizer with the soil, let the mixture be for 2 days, then remix everything using hoes.
After your land is ready, move your seedlings from the sowing media. Do this by lifting the soil that supports the rooting zone. Plant your seedlings by making holes using your hands with the size and depth of the holes depending on the size of your seedling roots. Make your planting distance about 10×15 cm from each other.
The care of lettuce farming
The basic care for curly lettuce farming consists of watering, fertilization, and weeding. Watering is done depending on the kind of weather your crop is faced with. If there’s no rain, watering should be done twice a day, in the morning and in the evening. Or you can do once a day in the middle of the day with a lot of water to avoid sudden wilting.
When your crop is 2 weeks old and your find that they’re not as fresh as they can be, can be seen from the color being faded green, add manure fertilization (chicken manure that is high in nitrogen is recommended) 2 tons per hectare. When your crop reaches 20 days, spray some organic liquid fertilizer 3 liters per hectare.
Even though the harvest cycle is quite quick, weeding is still needed because curly lettuce has short roots with low competing ability in nutrient searching if there are weeds. So make sure to pencil in some regular weeding, at least once during the entire farming process.
Weeding happens a bit differently in the dry and rainy season. In dry season, you simply pull them out and leave them on top of the soil as added green fertilizer or mulch to lessen evaporation. In rainy season, you pull them out and you get rid of them immediately to avoid the growth of unwanted fungus and diseases due to high humidity.
Pest and disease control
Common pests and diseases in curly lettuce farming:
- Asian trampsnail (Bradybaena similaris ferussac), it looks like a snail that is 2 cm in size. This pest may attack at any time. They usually hide at the inner part of leaf base. This pest attack causes holey leaves.
- Tangek (Parmalion pupilaris humb), looks a lot like asian trampsnail but without the house part. They cause holey leaves and usually attack in the dry season.
- Soft rot, caused by the Erwinia Carotovora bacteria, attacks the leaves. Starting from the edges, the leaf will turn brown in color then wilt entirely. This can happen to on site lettuces and lettuces that are ready to distribute.
- Leaf base rot, caused by Felicularia filamentosa bacteria. This disease attacks the leaf base and usually happens when it’s almost time for harvest.
Organic curly lettuce farming doesn’t allow the use of synthetic pesticides. Get rid of pests using cover, get rid of diseases using more manure fertilizer or phytopesticides. Regular watering and fertilization have been proven effective for pest control. Other efforts include healthy farming, clean environment management with proper irrigation and drainage system, and increasing plant’s immunity using potassium from bamboo leaves in compost.
Curly lettuce is ready for harvest around 20-30 days after planting, which is about 40-60 days from the start of the sowing process. The productivity can reach 15-20 tons per hectare.
You harvest your curly lettuce by pulling them out entirely, including their roots. After you do that, wash the roots clean and get rid of damaged leaves. Group your curly lettuce based on size. You should process it all very quickly because curly lettuce doesn’t handle heat and evaporation well after harvest. If distribution takes a while, make sure to store them in humid place near water or spray water on them regularly.