Detailed Guide to Bitter Melon Growing Techniques and Methods, Latest Cultivation Tutorial
Bitter melon is a short-day plant that prefers warmth and light, tolerates heat and moisture, and does not tolerate shade. It is not strict about day length; longer periods of light favor its healthy growth. It has relatively high requirements for soil moisture and air humidity, but does not tolerate waterlogging. It has broad adaptability and can be cultivated in many types of soil in both northern and southern China. In recent years, some vegetable growers in certain regions have also grown it in plastic tunnels or greenhouses.
Growing Conditions for Bitter Melon
1. Soil: For container growing, use garden soil mixed with an appropriate amount of lime, decomposed pig manure, superphosphate, plant ash, and the like. It can be sown and grown directly in pots, or seedlings can be transplanted into pots, with thin bamboo poles set up as a trellis for the vines to climb. In courtyards, it is often planted beside a sunny trellis, generally with a plant spacing of 40 to 50 cm. Enrich the soil with fertile nutrient soil, mounded 2 to 3 cm above ground level, and keep the soil consistently moist.
2. Temperature: Bitter melon has different temperature requirements at different stages of development. The optimum temperature for seed germination is 30°C to 35°C; the optimum temperature for seedling growth is 20°C to 25°C, with growth slowing below 15°C and poor growth below 10°C; the optimum temperature for flowering and fruiting is 20°C to 30°C, and at 25°C to 30°C the fruit set rate is high and the fruit develops rapidly; in the later growth stage, when the night temperature is 10°C and the daytime temperature is 15°C to 20°C, it can still set fruit normally.
3. Light: Bitter melon is not strict about day length, but insufficient light during the seedling stage reduces cold resistance and disease resistance, and the stems and leaves tend to grow leggy. During the flowering and fruiting stage, sufficient light favors stem and leaf growth and improves the fruit set rate, and the fruit also develops faster.
4. Water and Fertilizer: Bitter melon should have an adequate water supply, especially during the flowering and fruiting stage, when it needs more water; avoid both water shortage and prolonged waterlogging. Bitter melon is highly tolerant of fertilizer but sensitive to waterlogging, so choose well-drained sandy loam or clay loam with a deep soil layer for cultivation. Base fertilizer should mainly be decomposed organic fertilizer, and topdressing should mainly be decomposed human and livestock manure and urine, applied once a week. Seedling fertilizer should be applied thinly; once the flowering and fruiting stage begins, the concentration can be increased; after the peak fruiting stage, apply 1 to 2 additional applications of potassium fertilizer or compound fertilizer to extend the flowering and fruiting period.
Seedling-Raising Techniques for Bitter Melon
1. Site Selection and Land Preparation: Bitter melon is best sown in spring, so select the site and prepare the land early. Bitter melon likes moisture and warmth, tolerates fertilizer, and does not tolerate waterlogging, so choose a plot with a deep topsoil layer, high fertility, and convenient drainage and irrigation. Before land preparation, apply 5000 kg of bio-organic fertilizer, 40 kg of nitrogen fertilizer, 50 kg of phosphorus fertilizer, and 30 kg of potassium fertilizer per mu. Plow to a depth of 30 cm, level the soil, and form beds 1.6 m wide.
2. Germination: Start germination around mid-March. Before sowing, first scald the seeds with hot water at 55°C and stir; when the temperature drops to 30°C, soak the seeds for 12 hours (if the seeds are gently cracked open along a seam, it helps them absorb water, and the soaking time is 8 hours). Then wash the seeds, take them out, wrap them well in clean gauze, and place them in an incubator at about 30°C to germinate. Wash them once a day with warm water, and they will begin to sprout in about 4-5 days. In this way, pathogens carried by the seeds can be killed while ensuring uniform sprouting. When 50% of the seeds have white sprouts showing, sow them for seedling raising, using nutrient pots in a sunny cold frame. Roll paper into cylinders 8 cm in diameter and 10 cm high, fill them with nutrient soil, and arrange them in the seedbed. Sow 1 seed in each nutrient pot, then water immediately; after the water seeps through, sprinkle 1 cm of fine soil on top, then cover with plastic sheeting.
3. Sowing: The day before sowing, put the prepared nutrient soil (take garden soil that has never grown cucurbits, peat: vermiculite: decomposed dry human manure = 1:1:1:0.5, add 1 kg of diammonium phosphate per cubic meter, sift and mix evenly, then pile it up and cover tightly with plastic sheeting; it can be used after a few days, and it needs to be mixed evenly once more before use) into 10 cm x 10 cm nutrient pots, or into a prepared seedling bed (use wooden strips to mark the bed into 10 cm x 10 cm squares, and make a 1 cm deep hole in the middle of each square with a wooden stick), and water thoroughly. The next day, spray the nutrient soil with water again, then sprinkle a thin layer of sifted fine soil before sowing. Place the germinated seeds in the small holes (note: the sprout faces downward against the soil), cover the seeds with a small mound of soil about 1.5 cm thick, and then sprinkle a layer of fine soil over everything. Taking the Beijing area as an example, sowing is generally done in late March to early April, the seedling age is about 30-35 days, and they are transplanted to open fields in early May after the last frost.
4. Hardening Off: After sowing, seal the greenhouse to raise the temperature; set up a small arch tunnel in the sowing bed, cover with film, raise the temperature and retain moisture, keeping the daytime temperature at 30-35°C and the nighttime temperature above 15°C. When 50% of the seedlings have emerged, promptly uncover the film of the small arch tunnel again. From the first true leaf to the 4-true-leaf stage, ventilate and cool at noon to maintain 25°C—30°C. Keep the nighttime temperature at about 10°C. From 7 days—10 days before transplanting, control moisture and lower the seedbed temperature. After that, gradually increase the time the film is removed for ventilation until it is completely uncovered. Water whenever the soil looks dry, following the principle of controlling temperature but not water, to keep the seedlings growing vigorously. After that, gradually lower the temperature inside the tunnel, and remove all the tunnel film a few days before transplanting to harden the seedlings.
Growing Techniques for Bitter Melon
1. Transplanting and Thinning to Stand: When the seedlings have 5 leaves and 1 growing point, transplant them to the field; April 25 is the suitable planting period. Dig holes in the prepared bed, two rows per bed, with a row spacing of 1.2 m and a hole spacing of 50 cm, applying about 20 g of compound fertilizer per hole. Because bitter melon is a warmth-loving, fertilizer-tolerant crop, it needs sufficient base fertilizer. Apply 5000 kg of high-quality bio-organic fertilizer and 30 kg of diammonium phosphate per mu; after mixing evenly, first make flat beds at 1.5 m and water them; after a few days, when the soil is slightly dry and loose, make small raised beds 80-90 cm wide at the top and 10-15 cm high, and lay plastic mulch 5-7 days before transplanting. Two rows per bed, with a plant spacing of 60 cm, planting along marked lines. Do not dig the holes too deep; it is best if they can hold a little water after transplanting. To prevent the soil temperature from dropping, generally use the water-setting transplanting method; after the water in the hole seeps away, seal and press the hole firmly with soil to prevent air leaks. After transplanting, set up the trellis promptly. Because bitter melon grows very vigorously, set up sturdy inverted-V trellises. The spacing between trellis frames is 20 cm (30 cm for slightly thicker trellis material). Setting up the trellis promptly also improves the field microclimate, helping the seedlings recover quickly. Plant 1600 plants—1700 plants per mu, using 250-300 g of seed.
2. Intertillage and Weeding: Starting from the seedling stage, bitter melon should be intertilled, weeded, and earthed up promptly to prevent the soil around the plants from crusting. Generally, after transplanting and watering to help the seedlings recover, carry out the first intertillage when the surface soil is slightly dry and no longer sticky; if there is strong wind or the soil is too dry, water heavily once more before intertilling. The second intertillage can be done 10-15 days after the first, and care should be taken to protect new roots, so it should be shallow rather than deep. Each intertillage can be combined with the application of some high-quality farmyard manure, such as cake fertilizer, various poultry feathers, and decomposed chicken manure and pig manure. After the trellis is set up, when the vines have extended more than 50 cm and the root system has basically filled the whole row spacing, intertillage is generally no longer appropriate. However, weeds should be pulled promptly to prevent them from growing densely, thereby improving field ventilation and light penetration and reducing pest and disease damage. During the first intertillage, if missing plants or weak, diseased seedlings are found, replant promptly to ensure a full stand.
3. Building the Trellis: When bitter melon begins to send out vines, set up the “inverted-V” trellis well, connect the tops of the trellis with horizontal bars, and choose bamboo poles 2.5 m long and 3 cm in diameter for the fixed trellis poles. In the early stage, pay attention to manually tying the vines to help the plants climb onto the trellis. In the early growth stage, press the vines down at the right time to promote adventitious roots, expand the range of root absorption, and promote stem and vine growth. When the vines extend about 30 cm, set up inverted-V trellises on both sides of the row (like cucumber trellises), and guide the vines onto the trellis.
4. Pruning and Removing Branches: The axillary buds at the stem nodes of bitter melon are vigorous and easily produce side vines, but the female flowers on side vines appear relatively late. To ensure the advantage of the main vine in bearing fruit, side vines should be removed. After bitter melon is trained onto the trellis, no fruit should be kept on the main vine below 50 cm; female flowers should be removed to favor overall development. After the main vine has set 6—7 fruits securely, pinch off the growing tip, leaving 5—6 leaves, and at the same time remove the remaining secondary and tertiary vines.
5. Fertilizer and Water Management
① Bitter melon has a long growth period, with a harvest period of more than 3 months, so an adequate supply of water and fertilizer must be ensured. Especially once it enters the peak fruiting stage, if drought occurs, water once every 7 days. Before watering, apply urea or compound fertilizer in holes at 7 kg—10 kg per mu. If there is continuous rainy weather, pay attention to drainage, and at the same time spray potassium dihydrogen phosphate on the leaves 2 to 3 times.
② After the seedlings recover, water promptly to help them recover; because the temperature is still low at this time, the water should not be too much. After a few days, carry out deep intertillage promptly to conserve moisture, raise the soil temperature, and promote plant growth and development. Because the plants branch strongly, select 2-3 thick vines from the lower part, tie them to the trellis, and remove all the rest. During this period, generally do not water. Wait until the first fruit has fully set and begins to swell, then water and apply 10-15 kg of urea or 20-25 kg of ammonium bicarbonate per 667 m2 with the water. Because the plants have now entered the vigorous growth stage, water and fertilize according to weather changes, plant growth, and soil conditions; this is what is meant by watering based on "watching the sky, watching the ground, and watching the crops." It should be noted that because bitter melon has a relatively developed root system and strong growth vigor, do not water too frequently or too heavily, so as to avoid growing only vines without setting fruit, and to avoid poor ventilation and light penetration causing disease or knocking down the trellis, resulting in economic losses. About 40-50 days after transplanting, begin harvesting commercial fruit. The fruiting period requires relatively large amounts of fertilizer and water.
③ Although bitter melon likes moisture, it also dislikes waterlogging. If the roots are flooded, the leaves will yellow and wither, the fruit will rot, and root rot may occur, leading to wilting. For winter-spring bitter melon, temperatures in the early growth stage are relatively low, so water should be controlled appropriately to enhance cold resistance. On sunny days from flowering to before harvest, water appropriately, generally once every 2-3 days. During the harvest period, water demand is relatively high, so water 1-2 times a day. Watering should be done after sunrise or before sunset, and watering should not make the soil too wet. Summer-autumn bitter melon is in an environment with high temperatures and high evaporation, so watering or irrigation should be strengthened to regulate temperature and humidity. In the early stage, watering should be the main method, that is, using clean water and watering thoroughly. After the vines cover the trellis, furrow irrigation can be used to keep the soil moist, but furrow irrigation should preferably use half a furrow of water, so that the soil is moist but not waterlogged. In the rainy season, drainage work should be done promptly to prevent water accumulation from making the bed surface too wet and causing root rot and disease.
6. Pest and Disease Control: Because bitter melon has relatively strong disease resistance and few diseases, in the later growth stage leaf mold, powdery mildew, and the like generally occur. Generally use 0.5% aminooligosaccharide aqueous solution or 50% thiophanate-methyl wettable powder at 1000 times. Spray 20% omethoate at 1000 times to control aphids, and spray propargite at 1500-2000 times to control red spider mites. The main disease of bitter melon is anthracnose, which mostly occurs in the middle and late stages. For control, promptly remove residual, rotten, and diseased leaves. Use 0.5% aminooligosaccharide aqueous solution or thiophanate-methyl at 800 times—1000 times, or 70% chlorothalonil wettable powder at 600 times, spraying daily in the early stage of disease. The main pests are aphids and cabbage caterpillars, which can be controlled by spraying the leaves with decis emulsion at 1000 times—2000 times or 40% dimethoate emulsifiable concentrate at 1500 times.
7. Timely Harvest: Bitter melon grows and develops quickly; generally 10—12 days after flowering, the fruit has developed fully, its size has basically become fixed, the rind is still green or light green, and the seeds have not hardened. Harvested at this time, the flesh is tender, slightly bitter with a sweet note, and excellent in taste. If harvested too late, the crude fiber in the flesh increases, and it is not conducive to the growth of later fruits. For bitter melon kept for seed, harvest when the top of the fruit turns yellow; if harvested too late, the seed fruit easily splits open. The fruits on a single bitter melon plant mature one after another. During the peak fruiting period, pick the mature seed fruits once a day, using scissors when picking to avoid tearing the vines. At the same time, remove off-type plants and off-type fruits, and select and keep seed from those with consistent color and fruit shape. Pick on the same day, extract the seeds, wash them, and dry them the same day to ensure the seed germination rate.