From baby leaf lettuce to big, crisp heads, lettuce is easy to grow in spring and fall, when the soil is cool. Leaf color and texture vary with variety. All types of lettuce grow best when the soil is kept constantly moist, and outside temperatures range between 45 and 75 degrees Fahrenheit.
Lettuce is one of the longstanding high-value crops in the Cordillera. This vegetable is appropriate for the said location because of the location’s cold climate. Currently, an approximate of 407 hectares of Cordillera land is used for growing lettuce.
Lettuce (Lactuca sativa) is an economically-important member of the compositae family. This is a cool weather vegetable and grows in the ideal temperature of 60 to 70 Fahrenheit. Lettuce has five varieties including leaf or loose-leaf, Cos or romaine, crisphead, butterhead, and stem or asparagus lettuce.
Types to Try
- Loose-leaf varieties grow tender leaves in dense rosettes, but seldom form crisp inner heads. Some loose-leaf lettuce varieties have superior heat tolerance. Leaf lettuce type includes Salad Bowl, Early Curked Simpson, and Slobolt.
- Butterheads and bibb types quickly form small heads of leaves with stout, crunchy ribs. Some varieties have superior cold tolerance. This variety has tender and soft leaves with a delicate sweet flavor. The White Boston lettuce is of the butterhead variety.
- Romaine lettuce has elongated leaves with stiff ribs. Romaines often tolerate stressful weather better than other types of lettuce. This variety is often used in salads and sandwiches. White Paris Cos and Paris Island Cos belong to the Cos or romaine variety.
- Crisphead lettuce includes familiar iceberg types, as well as lush and leafy Batavian, or French Crisp, varieties which have great flavor and color, and are easy to grow. Crisphead lettuce includes the Great lakes, Oswego and Calmar.
All lettuce varieties are considered cool-season vegetables. This vegetable gives higher yield when the temperature is maintained no higher than fifteen to twenty degrees Celsius. Lettuce may grow on different kinds of soil. However, to achieve best results, it is recommended that lettuce be grown on sandy loam soil and clay loam soil.
Growing and Handling
There are two ways to plant lettuce. The first is direct seeding, and the second is by adapting the transplanting method. In direct seeding, the seed is directly plated in the soil. Direct seeding is often used for large scale operations.
In transplanting method, the seed is first planted and grown on a seed bed or seed container before it is moved to a larger farming area. Transplanting method is often used in small scale enterprises like home gardens.
To prepare the fertilizer, a handful of compost must be mixed with a tablespoon of complete fertilizer. A hectare of land would require approximately 500 kilos of fertilizer. Place this fertilizer in openings in the land area intended for planting. Cover the fertilizer with soil before planting. It is important to remember that crops should not be planted too near the fertilizer as this can damage the crops.
Direct seeding may be done by planting seeds 1/4 to 1/2 inch deep, using ten seeds per foot. A land hectare will approximately require 400 grams of seeds. Seeds may be planted in rows twelve to eighteen inches apart. Planted
seeds should be covered with fine soil to ensure their germination process. Immediately water the seeds after planting. Seedlings should be thinned to ensure better growth. Leaf lettuce should be thinned to four inches apart and Butterheads and Cos should be trimmed six to eight inches apart. Crisphead seedlings must be trimmed or transplanted ten to twelve inches apart in the row.
Transplanting method may be done by using a seedbed of 50 to 75cm wide, marked at every 6 cm. Spread the seeds on the seedbed and cover with soil. Ensure that the seedbed is regularly watered until the seedlings emerge. This will take approximately seven days after planting the seeds. Once the seedlings appear, the watering routine may be lessened. The seedlings may be transplanted after three weeks or when they have reached the height of 5cm to 8cm. Ensure that some soil still attach to the roots to protect the roots of the crop. Each transplanted lettuce should be given a space of 25 x 30cm. Immediately water the seedlings after transplanting them. Regularly water the growing seedlings.
Lettuce has shallow roots. As such, lettuce should be hoed and cultivated carefully. To ensure rapid development and high-quality lettuce, frequent light watering may be done. However, over watering, especially in heavy soils, may result in scalding or burning of the leaf margins. It is also important to use fertilizer on the soil to ensure that the vegetable is given the nutrients it needs, In less ideal weather conditions, organic mulches may be used to help moderate the soil temperature.
The most common pest in lettuce beds are aphids. Aphids are found on the underside of the leaves. Aphids may be yellow, green, black, brown, red or pinkish. They are pear shaped-insects and may or may not have wings. Aphids may be recognized by their size, ranging from 1/16 to 1/8 inch long, slender antennae and two tubes near their abdomen. These insects are drawn to succulent new growth, and draw great quantities of sap, thus causing the leaves and stems to become distorted. These insects are capable of transmitting plant pathogens and with its rapid population growth, several generations may occur. Thus its control is imperative.
A non-chemical method to control aphids is through washing them with a steady stream of water. Heavy applications of nitrogen fertilizer should also be avoided as this can encourage succulent plant growth. Lady beetles and aphis lions are natural predators that feed on aphids but these may not always ensure adequate control.
Chemical methods of control may be used upon consultation with the local government agricultural expert. Insecticides like Sevin or Malathion are not too harsh and may be used for control. It is important to follow the chemical’s recommended instructions as these chemicals may be harmful to the plant and to the people who will consume the vegetable. Insecticides should not be used on plants intended to be harvested in two weeks. Insecticides should also not be sprayed against the wind so they do not spray toward the person administering them. Proper garments for handling such chemicals must be used.
There are four diseases that commonly afflict lettuce beds. These diseases should be handled properly to ensure maximum yield.
Bottom Rot. This disease originates from a type of fungus called Rhizoctonia solani. This disease attacks the young leaves while it is still close to the ground. This disease causes plants to have reddish-brown lesions on the lettuce stems or the bottom of the head. When not managed or controlled, this disease can cause the leaf blades to rot until the whole head becomes dark and dry.
Infected plants with only the outer leaves affected may be saved by removing them from the field and harvesting the heads. However, when the entire head is infected, they should be discarded. Bottom rot may also be avoided by regular crop rotation.
Cercospora Leaf Spot. This disease is caused by the fungus Cercospora beticola. Cercospora leaf spot causes lesions on the side of leaves of infected crops. When left unmanaged, the infection spreads throughout the entire plant until it expires.
To control this disease, affected leaves should be removed and burned immediately. Chemical control of this disease may include spraying of zineb, maneb plus zinc sulfate or ziram.
Downy Mildew. This disease is caused by the fungus Bremia lactuca. The fungus mainly affects the older leaves, but may appear on any above-ground parts. This disease is characterized by a yellow area on the upper surface of the leaves and whitish or grayish on the same areas on the underside of the leaf.
Infected leaves may be trimmed. Fungicides such as maneb or zineb may be used to control this disease.
Lettuce Mosaic. This viral disease affects all lettuce types and is also seed-borne in all lettuce types. LM virus is harmless to consumers but can cause leaf distortions and discolorations that result to a decrease in the marketability of the crop.
LMV infections may be prevented by regular removal of weeds and administering insecticides for aphids that spread this virus.
Harvesting and Storage
Lettuce should be harvested when it has reached its ideal size for maximum profit. Harvest should be done when the crop has reached its fully developed head approximately the size of a cabbage or for leaf type lettuce, when the leaves are broad enough.
Head-type lettuce may take longer to harvest than leaf-type lettuce. It is advisable to harvest head-type lettuce when the head is thick and packed. Leaf lettuce should be harvested before it starts flowering.
Loose leaf lettuce may be harvested within thirty to forty-five days. Butterheads and romaine lettuce may be harvested in fifty to seventy days. Crisp head lettuce may be harvested in sixty to ninety days.
It is important to harvest lettuce in the afternoon to prevent rapid wilting of leaves and to keep the crops from becoming watery, which expedites crop expiration. It is recommended to avoid harvesting after rainfall or when the crop is still wet from dew to prevent the leaves from becoming brittle.
It is also important to use a long and sharp knife in harvesting lettuce, and cut the lettuce near the soil surface. Trim unwanted leaves, however leave four or five wrapper leaves. Harvested lettuce may be placed in an open container such as baskets or kaing.
Lettuce should be stored in a cool place after harvest. Leave harvested lettuce in an open container to prevent wilting. Lettuce should be cleaned the following day, and undesirable leaves should be removed before wrapping the lettuce in plastic. This procedure ensures a higher market value of the lettuce.
Lettuce is perishable and should not be stored for long periods. When stored in the refrigerator, lettuce should not be stored in plastic as this can accumulate water that speeds up lettuce expiration. Lettuce may be stored in the refrigerator for five days.
Proper storage must be used should the lettuce be transported in long journey. Containers used for transport should be properly ventilated. Baskets made of bamboo may be used.
Return on Investment
Production cost for growing lettuce is approximately Phpi2,ooo per hectare of crops. This capital includes costs of labor, land preparation for farming lettuce, and equipment. Also included are seed costs, fertilizers, and insecticides.
A ten sq. meter land can yield thirty kilos of lettuce. Subsequently, a hectare can yield three thousand kilos of lettuce. Should a kilo be sold at Php 10, a hectare can yield 145.70% profit.
It is important to remember that lettuce cannot be stored when prices are undesirable. As a result, lettuce growers depend on the demand of the product in the market. Keen planning, marketing and production practices must be adapted for successful lettuce growing.
Lettuce has a substantial potential in the industry simply because there is continuous demand. It is a stable ingredient in salads not only in the Philippines but in the world market as well.
author: Carmela Abaygar, Marid Digest, other source: motherearthnews.com, photo from topveg.com