Detailed Guide to Potted Cultivation Techniques for Colored Calla Lilies

Colored calla lily is a perennial herbaceous bulbous flower of the genus Zantedeschia in the Araceae family. Its flower shape is elegant and its colors are varied, making it a new favorite in the flower market, suitable for cultivation as cut flowers and pot flowers.

Botanical Characteristics of Potted Calla Lily

The leaves of colored calla lily are basal, entire, and emerald green, with some cultivars having white spots on the leaves; the petiole length is more than twice the leaf blade length. The flower stalk rises above the leaves, the spadix is yellow, and the spathe can be white, yellow, pink, red, or purple, resembling a horseshoe shape; the fruit is fleshy.

Early Preparation for Potted Calla Lily

Tubers: Colored calla lily tubers are propagated by seeds or daughter tubers. The growth lifespan of a tuber is 4 years. For potted tubers, select two-year-old cut flower tubers that have not been harvested, with 6 to 9 daughter tubers of 1 to 2 cm around the mother tuber, which are of the best quality. Three-year-old tubers have been harvested for one season of cut flowers, grow weakly, and the wounds from cut flower production are prone to infection by pathogens, resulting in a higher incidence of soft rot during cultivation.

Treat tubers with gibberellin plus fungicide to increase flower number and prevent soft rot. Generally, tubers treated with gibberellin produce twice the number of flowers compared to untreated tubers. In addition, gibberellin slightly increases plant height, slightly reduces leaf width, and can soften tissues.

A backpack sprayer can be used to spray gibberellin and fungicide. Avoid soaking tubers in the solution to reduce pathogen spread. The solution is prepared as follows: add 20 mL of 37.5% copper hydroxide solution per liter of clean water, plus 125 ppm gibberellin. Adding a certain amount of copper-based disinfectant to the gibberellin solution helps control pathogen spread and reduce soft rot. After mixing, the solution must not be left standing; it must be stirred to prevent precipitation. Tubers should be air-dried, not dried with a fan.

After receiving the tubers, growers should immediately open the packaging, remove tubers infected with soft rot, and then wash their hands to avoid spreading bacteria to other healthy tubers. If it is green mold or black mold, it does not matter. Place the tubers in a well-ventilated tray at below 18°C for two to three days before planting, so that wounds produced during transport can heal before planting. If storage lasts up to 6 weeks or more, place them in a dark, cool, ventilated place, such as a storage room at 10°C and 80% relative humidity. During storage, place the tubers with the sprouting side facing down in a single layer in plastic crates.

Container: Choose 12 cm to 20 cm tall plastic pots, which facilitate substrate drainage and aeration. Plant one or two tubers per pot.

Substrate: The cultivation substrate for colored calla lily is very important. The substrate should be clean, have good permeability, a pH between 6 and 6.5, and an EC value below 0.5. Colored calla lily rooting dislikes high-salt substrates, and the optimal porosity is 20%±5%. Use 30% to 50% coarse-grade peat, mixed with large-particle perlite, coarse sand, fir bark, pumice, or slag. Because pine bark is incompatible with paclobutrazol, use it with caution or avoid it. Coarse sand can stabilize the pot and make it less likely to tip over. Gypsum or lime not only helps balance pH but also provides calcium beneficial to healthy plant growth.

The recommended substrate formula is as follows: 5 parts coarse peat, 2 parts perlite, 2 parts 3.2 mm to 6.4 mm fir bark, 1 part coarse sand. Coconut coir and coconut husk fiber are high-quality salt-free substrate mixing materials. In cut flower cultivation, they can improve flower and stem quality; however, when growing potted plants, they increase the incidence of tuber disease. Therefore, coconut coir is not recommended as a potted substrate for colored calla lily.

When planting in pots, place the tubers with the sprouting eyes facing up and the rounded side facing down, flat. The roots of colored calla lily grow from around the sprouting eyes on the upper part of the tuber, so pay attention to proper planting depth. The tubers should be covered with 2.5 cm to 3.8 cm of substrate. If the tuber is covered too shallowly, the roots will be exposed above the soil and easily threatened by light and dry air; if the tuber is exposed on the surface of the pot soil, new roots will have difficulty growing.

After potting, water thoroughly with clean water, place on a germination cart, and germinate in a germination room or small greenhouse at a constant temperature of 22°C, which helps uniform germination and reduces heating costs. After about 6 days of germination, when 50% of the potted flowers have emerged sprouts, they can be moved out of the germination room, or moved out in two batches. If germinating in the greenhouse, shade netting should be used to prevent excessive temperature.

Growth Period Management of Potted Calla Lily

Stage 1: To prevent disease, drench the roots with a four-in-one fungicide solution on the 4th day after potting. The four-in-one fungicide solution includes 4 to 8 mL per 100 L of metalaxyl-M, 98 g per 100 L of fosetyl-aluminum, 30 g per 100 L of azoxystrobin, and 60 g to 120 g per 100 L of streptomycin sulfate.

From potting until the seedlings are 2.5 cm to 7.5 cm tall, during the period from 12 days to 25 days, maintain a daytime temperature of 24°C and a nighttime temperature of 18°C to 19°C. In early winter production, appropriate heating can improve plant vigor and growth. After the seedlings have grown for 6 days to 10 days and reached a height of 1.25 cm to 5 cm, drench with paclobutrazol at 6 ppm to 8 ppm. Do not apply paclobutrazol to small-flowered dwarf cultivars; use a lower concentration for compact cultivars; for tall, vigorously growing cultivars suitable for large pot flowers and cut flowers, drench twice at a higher concentration. If tuber germination is uneven, first drench the pots whose sprouts have reached the required height and mark them; after the pots whose sprouts have not reached the height meet the standard, drench them as well.

Stage 2: About one week after sprouting, or starting from the first paclobutrazol drench until the leaves unfold, depending on the cultivar, this should be 14 days to 28 days or 50 days. Maintain 21°C to 24°C during the day and 12°C to 15°C at night. Cooler nights reduce plant height and delay production time.

Stage 3: Flower buds begin to grow and color. Depending on the season and conditions, this is roughly from day 50 to day 75. Maintain a daytime temperature of 18°C and a nighttime temperature of 10°C to 13°C. In Stages 2 and 3, if light is insufficient or paclobutrazol drenching has not been used, the temperature can be lowered by 1°C to 2°C. This low temperature can improve plant growth habits and reduce the amount of paclobutrazol used, but it will prolong the growth period. It is worth noting that when the temperature is 10°C or slightly below 10°C, calla lily will stop growing, which can delay its flowering period and postpone market release.

Negative temperature difference or morning cold stimulation: Two to 5 days after the first use of paclobutrazol, cool the greenhouse by 3°C to 6°C in the early morning from 5 a.m. to 8 a.m. to create a negative temperature difference, that is, use the cold stimulation method. This can reduce the amount of paclobutrazol used and promote robust plants with a compact habit. Cold stimulation technology will not prolong the growth period of forced cultivation.

The only way to accelerate calla lily flowering is to increase the average temperature. However, in a warm climate, especially under low light, plants will grow leggy, and in severe cases the leaves and flower buds will droop. In the early stage of plant growth, if pale yellow leaves appear, it is usually caused by excessively high temperature, so it is better to advance the planting time. Low temperature will slow plant growth, and this is better than planting late and increasing the temperature in Stages 2 and 3.

Light: Colored calla lily needs sufficient light for growth, preferably controlled at 5,000 to 50,000 Lux, and is not sensitive to photoperiod. Many flower growers place colored calla lilies the way they place bromeliads and anthuriums, too crowded, resulting in poor ventilation and light transmission, which leads to leggy and weak potted flowers. The placement density of colored calla lilies on the bench should be such that the leaves of adjacent plants do not touch each other and there is a slight gap. In winter, the Yangtze River basin has low temperatures and many cloudy and rainy days; plastic film greenhouses should be re-covered with new film, and fixed secondary films should not be used. The secondary film should be opened during the day to ensure sufficient light.

Humidity and ventilation: Under conditions of poor air circulation, weak light, or crowded plants, excessively high humidity and growth environments that are too hot or too cold can cause diseases of the leaves and root system. For producing Chinese New Year flowers, internal circulation fans should be turned on overnight to create horizontal airflow in the greenhouse and reduce humidity. Guttation at leaf tips or water droplets hanging on leaves can induce bacterial rot. It is worth noting that an overly dry environment will make leaves narrower, affecting plant vigor and even the number of flower buds, ultimately affecting product quality.

Water: Use a clean, pathogen-free water source with an EC value below 1.5, which is beneficial to healthy plant growth. Water supplies with high salinity or other problems need water treatment before use.

Watering depends on the season, temperature, and the water-holding capacity of the substrate. Keep the pot soil moist, avoiding both over-wetting and over-drying. After the first root drench with the four-in-one preventive fungicide, water lightly until the leaves unfold, and carry out the second fungicide root drench at 14 days to 21 days. Avoid water accumulation in the pot soil, otherwise diseases are easily spread. When applying slow-release fertilizer under warm conditions, alternating extreme drought and excessive moisture will damage the root system and greatly increase the possibility of plant infection by pathogens.

If the pot soil is too dry, flower buds will wither. Watering should be sufficient and thorough; water seeping from the bottom of the pot can carry away excessive salts accumulated in the pot soil. Avoid tidal irrigation and sub-irrigation from the bottom to prevent disease spread. Long-term over-wet pot soil will cause moss to grow on the surface, which is not conducive to disease management in calla lily.

Fertilizer: The ideal initial fertilization is to mix 15-3-15 slow-release fertilizer into the substrate, with trace elements if possible. Keep the pot soil moist, with an EC value between 1.5 and 2.0, avoiding exceeding 2.5. Do not use ammoniacal nitrogen. It is recommended to use a constant prepared liquid fertilizer at 100 ppm to 150 ppm, with added trace elements. Under weak light or poor growing conditions, increase the fertilizer concentration. For example, if fertilizing once a week, use a 100 ppm concentration; if once every two weeks, use a 200 ppm concentration; if fertilizing infrequently, use a 300 ppm concentration. You can add 1.5 g of 15-3-15 slow-release fertilizer to each 15 cm pot. If the pot soil is too dry and the temperature exceeds 25°C, slow-release fertilizer over 30 days will cause fertilizer burn, producing salt burn at the leaf edges. Adding 1.78 kg of lime and dolomite per cubic meter of substrate can provide calcium for the plants and increase disease resistance. To deepen leaf color, add 46.9 mL of chelated iron to 100 L of water to make a solution, and spray weekly after the leaves unfold. The use of paclobutrazol and lower temperatures can also deepen leaf color.

To increase ventilation and light penetration for large-leaved cultivars, reduce the nitrogen concentration and increase phosphorus in the fertilizer. Using 10-30-20 slow-release fertilizer allows plants to produce more robust and smaller entire leaves and can increase the number of flowers.

In the last 6 weeks of the growth period, water thoroughly with clean water three to five times, which can clean the leaf surface and prevent salt accumulation in the pot soil from burning the root system.

Plant Growth Regulation: Paclobutrazol is the most effective growth regulator for calla lily. When the sprouts of colored calla lily grow to 1.25 cm to 5 cm high, apply the first paclobutrazol spray. The pot soil must be moist, preferably one or two days after fertilizing or after the second fungicide root drench. The second paclobutrazol spray is usually 6 days to 10 days after the first application. Using low-concentration (6 ppm to 10 ppm) paclobutrazol in two applications is more effective than a single drench of a higher-concentration solution. It is recommended to spray 177 mL per 15 cm pot and 118 mL per 11 cm pot. Using too much paclobutrazol will cause the plant to become stunted in shape, reduce the number of flowers, and delay the flowering period. Correct use of paclobutrazol can greatly improve the quality of finished flowers and facilitate long-distance transport.

Do not use chlormequat on narrow-leaved small-flowered cultivars; large-flowered cultivars can be root-drenched twice with 8 ppm paclobutrazol; tall cut flower cultivars can be root-drenched two or three times with 10 ppm paclobutrazol.

In addition to concentration, many factors affect the effectiveness of paclobutrazol, such as weak light or short-day conditions, excessively high or low temperature, pot soil that is too dry, and watering immediately after chlormequat spraying. The use of paclobutrazol is not only a science but also an art. The same concentration will have different effects in different cultivars, regions, and seasons. To accurately grasp the timing and concentration of spraying, it is necessary to keep detailed records of the environmental conditions at each spraying, the substrate moisture at the time of use, and the temperature and light conditions after use.

Pest and Disease Control: The main diseases of colored calla lily are tuber soft rot caused by Erwinia bacteria, as well as banded sclerotial blight, etc. When yellow leaves appear on the plant, growers only need to remove the plastic pot to see that the corresponding roots along the pot wall below the yellow leaves appear water-soaked and transparent; these are diseased roots, while healthy roots are white.

Check plants weekly for the following conditions: root browning, uneven growth, plant disease, weak roots, etc. Once lesions are found, timely control measures should be taken. For pretreated corms, carry out the first fungicide root drench within two to 6 days after the initial watering. If they are not pretreated tubers, root-drench within two to three days after the initial watering; the second root drench should be carried out 14 days to 21 days after the first root drench; the third root drench should be carried out 21 days to 28 days after the second. All spraying and root drenching should be done in the morning, or early enough that all leaf surfaces can dry completely overnight.

For producing Chinese New Year flowers, because new leaves grow quickly and the greenhouse is closed with high humidity, young tissues are prone to bacterial diseases, so copper-based products or azoxystrobin should be sprayed two or three times.

Controlling insect vectors such as fungi, mosquitoes, small flies, and whiteflies is crucial because they can transmit bacteria and other diseases. Thrips can transmit leaf viruses such as impatiens necrotic spot and tomato spotted wilt; aphids can transmit taro mosaic virus. Generally speaking, calla lily has some resistance to foliar spray phytotoxicity, and most insecticides can be used safely.

If plants are infected with soft rot, promptly remove the diseased plants from the greenhouse. In addition, greenhouse sanitation is crucial; do not grow multiple plant species mixed together in one greenhouse.

Potted Calla Lily Cultivation Techniques | Colored Calla Lily Planting Techniques | Calla Lily Botanical Characteristics

Potted Calla Lily Cultivation Techniques | Colored Calla Lily Planting Techniques | Calla Lily Botanical Characteristics --- Colored calla lily is a perennial herbaceous bulbous flower of the genus Zantedeschia in the Araceae family. Its flower shape is elegant and its colors are varied, making it a new favorite in the flower market, suitable for cultivation as cut flowers and pot flowers.

Botanical Characteristics of Potted Calla Lily

Early Preparation for Potted Calla Lily

Treat tubers with gibberellin plus fungicide to increase flower number and prevent soft rot. Generally, tubers treated with gibberellin produce twice the number of flowers compared to untreated tubers. In addition, gibberellin slightly increases plant height, slightly reduces leaf width, and can soften tissues.

A backpack sprayer can be used to spray gibberellin and fungicide. Avoid soaking tubers in the solution to reduce pathogen spread. The solution is prepared as follows: add 20 mL of 37.5% copper hydroxide solution per liter of clean water, plus 125 ppm gibberellin. Adding a certain amount of copper-based disinfectant to the gibberellin solution helps control pathogen spread and reduce soft rot. After mixing, the solution must not be left standing; it must be stirred to prevent precipitation. Tubers should be air-dried, not dried with a fan.

After receiving the tubers, growers should immediately open the packaging, remove tubers infected with soft rot, and then wash their hands to avoid spreading bacteria to other healthy tubers. If it is green mold or black mold, it does not matter. Place the tubers in a well-ventilated tray at below 18°C for two to three days before planting, so that wounds produced during transport can heal before planting. If storage lasts up to 6 weeks or more, place them in a dark, cool, ventilated place, such as a storage room at 10°C and 80% relative humidity. During storage, place the tubers with the sprouting side facing down in a single layer in plastic crates.

Container: Choose 12 cm to 20 cm tall plastic pots, which facilitate substrate drainage and aeration. Plant one or two tubers per pot.

Substrate: The cultivation substrate for colored calla lily is very important. The substrate should be clean, have good permeability, a pH between 6 and 6.5, and an EC value below 0.5. Colored calla lily rooting dislikes high-salt substrates, and the optimal porosity is 20%±5%. Use 30% to 50% coarse-grade peat, mixed with large-particle perlite, coarse sand, fir bark, pumice, or slag. Because pine bark is incompatible with paclobutrazol, use it with caution or avoid it. Coarse sand can stabilize the pot and make it less likely to tip over. Gypsum or lime not only helps balance pH but also provides calcium beneficial to healthy plant growth.

The recommended substrate formula is as follows: 5 parts coarse peat, 2 parts perlite, 2 parts 3.2 mm to 6.4 mm fir bark, 1 part coarse sand. Coconut coir and coconut husk fiber are high-quality salt-free substrate mixing materials. In cut flower cultivation, they can improve flower and stem quality; however, when growing potted plants, they increase the incidence of tuber disease. Therefore, coconut coir is not recommended as a potted substrate for colored calla lily.

When planting in pots, place the tubers with the sprouting eyes facing up and the rounded side facing down, flat. The roots of colored calla lily grow from around the sprouting eyes on the upper part of the tuber, so pay attention to proper planting depth. The tubers should be covered with 2.5 cm to 3.8 cm of substrate. If the tuber is covered too shallowly, the roots will be exposed above the soil and easily threatened by light and dry air; if the tuber is exposed on the surface of the pot soil, new roots will have difficulty growing.

After potting, water thoroughly with clean water, place on a germination cart, and germinate in a germination room or small greenhouse at a constant temperature of 22°C, which helps uniform germination and reduces heating costs. After about 6 days of germination, when 50% of the potted flowers have emerged sprouts, they can be moved out of the germination room, or moved out in two batches. If germinating in the greenhouse, shade netting should be used to prevent excessive temperature.

Growth Period Management of Potted Calla Lily

From potting until the seedlings are 2.5 cm to 7.5 cm tall, during the period from 12 days to 25 days, maintain a daytime temperature of 24°C and a nighttime temperature of 18°C to 19°C. In early winter production, appropriate heating can improve plant vigor and growth. After the seedlings have grown for 6 days to 10 days and reached a height of 1.25 cm to 5 cm, drench with paclobutrazol at 6 ppm to 8 ppm. Do not apply paclobutrazol to small-flowered dwarf cultivars; use a lower concentration for compact cultivars; for tall, vigorously growing cultivars suitable for large pot flowers and cut flowers, drench twice at a higher concentration. If tuber germination is uneven, first drench the pots whose sprouts have reached the required height and mark them; after the pots whose sprouts have not reached the height meet the standard, drench them as well.

Stage 2: About one week after sprouting, or starting from the first paclobutrazol drench until the leaves unfold, depending on the cultivar, this should be 14 days to 28 days or 50 days. Maintain 21°C to 24°C during the day and 12°C to 15°C at night. Cooler nights reduce plant height and delay production time.

Stage 3: Flower buds begin to grow and color. Depending on the season and conditions, this is roughly from day 50 to day 75. Maintain a daytime temperature of 18°C and a nighttime temperature of 10°C to 13°C. In Stages 2 and 3, if light is insufficient or paclobutrazol drenching has not been used, the temperature can be lowered by 1°C to 2°C. This low temperature can improve plant growth habits and reduce the amount of paclobutrazol used, but it will prolong the growth period. It is worth noting that when the temperature is 10°C or slightly below 10°C, calla lily will stop growing, which can delay its flowering period and postpone market release.

Negative temperature difference or morning cold stimulation: Two to 5 days after the first use of paclobutrazol, cool the greenhouse by 3°C to 6°C in the early morning from 5 a.m. to 8 a.m. to create a negative temperature difference, that is, use the cold stimulation method. This can reduce the amount of paclobutrazol used and promote robust plants with a compact habit. Cold stimulation technology will not prolong the growth period of forced cultivation.

The only way to accelerate calla lily flowering is to increase the average temperature. However, in a warm climate, especially under low light, plants will grow leggy, and in severe cases the leaves and flower buds will droop. In the early stage of plant growth, if pale yellow leaves appear, it is usually caused by excessively high temperature, so it is better to advance the planting time. Low temperature will slow plant growth, and this is better than planting late and increasing the temperature in Stages 2 and 3.

Light: Colored calla lily needs sufficient light for growth, preferably controlled at 5,000 to 50,000 Lux, and is not sensitive to photoperiod. Many flower growers place colored calla lilies the way they place bromeliads and anthuriums, too crowded, resulting in poor ventilation and light transmission, which leads to leggy and weak potted flowers. The placement density of colored calla lilies on the bench should be such that the leaves of adjacent plants do not touch each other and there is a slight gap. In winter, the Yangtze River basin has low temperatures and many cloudy and rainy days; plastic film greenhouses should be re-covered with new film, and fixed secondary films should not be used. The secondary film should be opened during the day to ensure sufficient light.

Humidity and ventilation: Under conditions of poor air circulation, weak light, or crowded plants, excessively high humidity and growth environments that are too hot or too cold can cause diseases of the leaves and root system. For producing Chinese New Year flowers, internal circulation fans should be turned on overnight to create horizontal airflow in the greenhouse and reduce humidity. Guttation at leaf tips or water droplets hanging on leaves can induce bacterial rot. It is worth noting that an overly dry environment will make leaves narrower, affecting plant vigor and even the number of flower buds, ultimately affecting product quality.

Water: Use a clean, pathogen-free water source with an EC value below 1.5, which is beneficial to healthy plant growth. Water supplies with high salinity or other problems need water treatment before use.

Watering depends on the season, temperature, and the water-holding capacity of the substrate. Keep the pot soil moist, avoiding both over-wetting and over-drying. After the first root drench with the four-in-one preventive fungicide, water lightly until the leaves unfold, and carry out the second fungicide root drench at 14 days to 21 days. Avoid water accumulation in the pot soil, otherwise diseases are easily spread. When applying slow-release fertilizer under warm conditions, alternating extreme drought and excessive moisture will damage the root system and greatly increase the possibility of plant infection by pathogens.

If the pot soil is too dry, flower buds will wither. Watering should be sufficient and thorough; water seeping from the bottom of the pot can carry away excessive salts accumulated in the pot soil. Avoid tidal irrigation and sub-irrigation from the bottom to prevent disease spread. Long-term over-wet pot soil will cause moss to grow on the surface, which is not conducive to disease management in calla lily.

Fertilizer: The ideal initial fertilization is to mix 15-3-15 slow-release fertilizer into the substrate, with trace elements if possible. Keep the pot soil moist, with an EC value between 1.5 and 2.0, avoiding exceeding 2.5. Do not use ammoniacal nitrogen. It is recommended to use a constant prepared liquid fertilizer at 100 ppm to 150 ppm, with added trace elements. Under weak light or poor growing conditions, increase the fertilizer concentration. For example, if fertilizing once a week, use a 100 ppm concentration; if once every two weeks, use a 200 ppm concentration; if fertilizing infrequently, use a 300 ppm concentration. You can add 1.5 g of 15-3-15 slow-release fertilizer to each 15 cm pot. If the pot soil is too dry and the temperature exceeds 25°C, slow-release fertilizer over 30 days will cause fertilizer burn, producing salt burn at the leaf edges. Adding 1.78 kg of lime and dolomite per cubic meter of substrate can provide calcium for the plants and increase disease resistance. To deepen leaf color, add 46.9 mL of chelated iron to 100 L of water to make a solution, and spray weekly after the leaves unfold. The use of paclobutrazol and lower temperatures can also deepen leaf color.

To increase ventilation and light penetration for large-leaved cultivars, reduce the nitrogen concentration and increase phosphorus in the fertilizer. Using 10-30-20 slow-release fertilizer allows plants to produce more robust and smaller entire leaves and can increase the number of flowers.

In the last 6 weeks of the growth period, water thoroughly with clean water three to five times, which can clean the leaf surface and prevent salt accumulation in the pot soil from burning the root system.

Plant Growth Regulation: Paclobutrazol is the most effective growth regulator for calla lily. When the sprouts of colored calla lily grow to 1.25 cm to 5 cm high, apply the first paclobutrazol spray. The pot soil must be moist, preferably one or two days after fertilizing or after the second fungicide root drench. The second paclobutrazol spray is usually 6 days to 10 days after the first application. Using low-concentration (6 ppm to 10 ppm) paclobutrazol in two applications is more effective than a single drench of a higher-concentration solution. It is recommended to spray 177 mL per 15 cm pot and 118 mL per 11 cm pot. Using too much paclobutrazol will cause the plant to become stunted in shape, reduce the number of flowers, and delay the flowering period. Correct use of paclobutrazol can greatly improve the quality of finished flowers and facilitate long-distance transport.

Do not use chlormequat on narrow-leaved small-flowered cultivars; large-flowered cultivars can be root-drenched twice with 8 ppm paclobutrazol; tall cut flower cultivars can be root-drenched two or three times with 10 ppm paclobutrazol.

In addition to concentration, many factors affect the effectiveness of paclobutrazol, such as weak light or short-day conditions, excessively high or low temperature, pot soil that is too dry, and watering immediately after chlormequat spraying. The use of paclobutrazol is not only a science but also an art. The same concentration will have different effects in different cultivars, regions, and seasons. To accurately grasp the timing and concentration of spraying, it is necessary to keep detailed records of the environmental conditions at each spraying, the substrate moisture at the time of use, and the temperature and light conditions after use.

Pest and Disease Control: The main diseases of colored calla lily are tuber soft rot caused by Erwinia bacteria, as well as banded sclerotial blight, etc. When yellow leaves appear on the plant, growers only need to remove the plastic pot to see that the corresponding roots along the pot wall below the yellow leaves appear water-soaked and transparent; these are diseased roots, while healthy roots are white.

Check plants weekly for the following conditions: root browning, uneven growth, plant disease, weak roots, etc. Once lesions are found, timely control measures should be taken. For pretreated corms, carry out the first fungicide root drench within two to 6 days after the initial watering. If they are not pretreated tubers, root-drench within two to three days after the initial watering; the second root drench should be carried out 14 days to 21 days after the first root drench; the third root drench should be carried out 21 days to 28 days after the second. All spraying and root drenching should be done in the morning, or early enough that all leaf surfaces can dry completely overnight.

For producing Chinese New Year flowers, because new leaves grow quickly and the greenhouse is closed with high humidity, young tissues are prone to bacterial diseases, so copper-based products or azoxystrobin should be sprayed two or three times.

Controlling insect vectors such as fungi, mosquitoes, small flies, and whiteflies is crucial because they can transmit bacteria and other diseases. Thrips can transmit leaf viruses such as impatiens necrotic spot and tomato spotted wilt; aphids can transmit taro mosaic virus. Generally speaking, calla lily has some resistance to foliar spray phytotoxicity, and most insecticides can be used safely.

If plants are infected with soft rot, promptly remove the diseased plants from the greenhouse. In addition, greenhouse sanitation is crucial; do not grow multiple plant species mixed together in one greenhouse.

Key Points to Note for Potted Colored Calla Lily

The flower language of calla lily is beautiful, representing faithful and unwavering love, so everyone is particularly fond of calla lily. The calla lily commonly seen is white, but there is another type of calla lily called colored calla lily, which I believe everyone has also seen. So what are the key points to note for potted colored calla lily? Let me introduce them below.

Key Point One for Potted Colored Calla Lily

The pot soil for potted colored calla lily should be mainly sandy loam. You can mix 1/3 garden soil and 1/3 leaf mold, then add 1/5 organic fertilizer to cultivate colored calla lily. Because its root system grows on the upper part of the corm, the bottom layer of the pot soil should be padded with permeable and breathable cinder or coarse sand. The flower pot should preferably be a shallow pot, not a cylindrical pot.

Key Point Two for Potted Colored Calla Lily

Fertilization for colored calla lily should mainly be phosphorus and potassium fertilizer, especially when the scape is emerging and buds are showing, promptly spray potassium dihydrogen phosphate solution at a concentration of 0.1% to 0.2%, to promote thick, straight, and lodging-resistant flower stalks. If saving seeds, after fruit set, spray once every 10 days, 2 to 3 times in total. Potted plants have limited nutrients, so apply thin fertilizer frequently to continuously replenish nutrients in the pot soil.

Key Point Three for Potted Colored Calla Lily

Like ordinary white calla lily, colored calla lily likes a warm and humid environment and is not tolerant of drought. The pot soil should be kept moist and must not lack water. If the environment is dry, spray water on the ground to maintain a humid micro-environment.

Colored calla lily likes sunlight, but is afraid of summer sun exposure. Direct sunlight will burn the leaves and spathe bracts. Therefore, shade should be provided in summer, with a shading rate of 50%. However, if it grows for a long time in a dark environment with insufficient sunlight, flowering will be affected, or it may not flower at all; even if it flowers, the color will be pale, detracting from ornamental value. In spring and autumn, shading is not necessary.

Key Point Four for Potted Colored Calla Lily

Colored calla lily is not cold-tolerant and likes warmth. When planting in the southern Liaoning region, generally divide and pot in September in autumn. Plant the same diameter flowering corms per pot, 3 can be planted, arranged in a triangular pattern. In autumn it can root, and in winter it goes dormant; store indoors, keeping at 5°C, and the flower pots can be stacked. In the following spring, when the temperature is 10°C to 15°C, water should be given. If the indoor temperature is high and sprouting is early, flowering generally occurs in June and July; in some cases with high temperature and good management, flowers can be seen in early June.