What are the open-field planting methods for gladiolus?
Open-field planting methods for gladiolus. Gladiolus can generally be planted in garden soil. Before planting, first turn the soil and apply base fertilizer, then plant according to corm size separately, with the covering depth preferably 2 to 3 times the corm diameter. For container planting, use fertile, loose sandy loam mixed with sufficient base fertilizer, and after planting water thoroughly 1 to 2 times, then loosen the soil to harden the seedlings. Before 3 leaves have grown, water as little as possible to prevent the plants from growing leggy, which affects flower bud differentiation.
When entering the vigorous growth period, the plants must not lack water, especially during the spike emergence and flowering stage, when water and fertilizer must be sufficient. Apply liquid fertilizer 3 to 4 times during the growing period. About two months after flowering, when the leaves turn yellow and the new corms have developed fully, cut off the stems and leaves about 5 cm above the ground, dig out the new corms, dry them, remove the remnants of the old corms, place them in gauze bags, and store them over winter indoors at 5 to 8°C with ventilation. During storage, check frequently. If moisture is found, put the whole bag out in the sun again. If any mold or rot is found, pick it out and discard it at once.
Gladiolus is usually propagated by dividing corms; those with a diameter of more than 3 cm can bloom in the same year. It can also be propagated by cutting the corms into sections, but each piece needs a strong bud, and the cut surface should be smeared with plant ash to prevent rot. The above is an introduction to open-field planting methods for gladiolus.
Soil requirements for open-field production technology of cut gladiolus
I. Soil structure
The range of soils suitable for gladiolus growth is very wide; as long as the soil structure and drainage are good, gladiolus can grow well. Among them, sandy loam is best. The water and air conditions of this soil are suitable for the growth of gladiolus roots and corms. Strongly clayey soil often affects gladiolus growth and cut flower quality because of poor aeration and easy water accumulation, so heavy clay soil should be amended with decomposed farmyard manure before land preparation to improve soil structure. However, do not use undecomposed human feces and urine, because during its decomposition process it will have adverse effects on plant growth, and in moist heavy clay soil its binding effect will also worsen the problem of poor soil aeration. When planting on loose sandy soil, after planting the corms, straw, peat and other loose organic matter can be used to cover the soil surface to keep the soil moist and prevent soil loss.
II. Soil pH
The pH range for gladiolus growth is 6.0 to 7.0, with the optimum pH being 6.5. Soil pH should be measured before planting. When pH is less than 5, it will be unfavorable to inflorescence growth, and soil pH can be raised by broadcasting lime onto the soil. Lime should be applied to the soil at least 1 month before planting and fully mixed evenly. If pH is greater than 7.5, it will cause the plant's absorption of mineral nutrients such as iron to be affected, resulting in nutrient deficiency symptoms. Applying a large amount of organic fertilizer to the soil can lower soil pH. When iron deficiency is severe, chelated iron such as Fe-EDTA can be applied to improve the availability of iron ions. Soil pH can also be adjusted by applying physiologically acidic fertilizers such as superphosphate and physiologically alkaline fertilizers such as calcium nitrate.
III. Soil ion concentration
The growth of gladiolus is relatively sensitive to the concentration of salt ions in the soil. Too high a salt ion concentration will hinder root growth and plant flowering. Generally, the total salt ion concentration should be less than 2 mS/cm (millisiemens per centimeter), and especially the chloride ion concentration must not exceed 3 mmol/L. If the chloride ion level in the soil is too high, it can be controlled by irrigation. At the same time, note that the amount of fertilizer applied should not be too much. The chloride ion content in irrigation water should be no more than 200 mg/L in a greenhouse and less than 600 mg/L in the open field. Also avoid soil drying, which causes salt concentration to rise.
IV. Soil fertility
When the soil is relatively poor, base fertilizer should be applied before planting. Organic fertilizer is preferable as base fertilizer and can improve soil structure. If soil fertility is sufficient, fertilization may be unnecessary. This is because, as a bulbous flower, the gladiolus corm stores sufficient nutrients to support its own early growth, while too much fertilizer will increase the soil salt ion concentration and instead be unfavorable to plant growth; in particular, excessive nitrogen fertilizer will increase the incidence of plant rot disease.
V. Site selection
When planting gladiolus, in addition to paying attention to soil characteristics, the transportation issue of the planting site must also be considered. Areas close to railways, highways and other convenient transportation should be chosen for cut flower production, so as to facilitate the transport and sale of cut flowers. There must also be sufficient water sources, flat terrain, and convenient drainage and irrigation. Pay attention to the effect of water quality on the quality of gladiolus cut flowers; in particular, water containing fluoride ions and chloride ions will reduce plant growth and the ornamental value of cut flowers. Fluoride in the air can also cause serious harm. As long as there is fluoride at a concentration of 0.01 μg/g in the atmosphere for 30 hours, leaf tip scorch and brown leaf tip spots will appear on gladiolus. Therefore, gladiolus planting sites should be far away from factories that emit harmful fluoride gas. Planting sites should also avoid, as much as possible, garden plots with severe pests and diseases, especially areas where leguminous plants have been planted. At the same time, pay attention to insects such as aphids that transmit viruses. A crop rotation system and soil disinfection should be implemented at the planting site.
VI. Bed making
After the soil is plowed and disinfected, the land can be prepared and beds made. In areas with a high groundwater table and abundant rainfall, raised beds or ridge planting should be used. In dry areas, flat beds can be made. Different bed-making methods should be chosen for different irrigation methods. If flooding irrigation is used, flat beds should be avoided as much as possible, and ridge planting or raised beds can be used. This is because flooding irrigation on flat beds causes soil compaction, damages soil structure, and affects the yield and quality of cut flowers. If sprinkler irrigation is used, both flat beds and raised beds are suitable. The base of a raised bed is about 50 cm wide, the bed surface is 25 cm wide, and sufficient soil should be left on both sides of the bed surface for hilling up after the plants grow, to prevent lodging. A flat bed is about 1.0 m wide. If the soil is dry, water thoroughly once a few days before planting the gladiolus corms, which both keeps the soil moist and makes planting operations easier.
In short, before planting gladiolus, one should first fully understand the soil's physical properties such as texture and water-air conditions, as well as chemical characteristics such as soil pH, salinity (EC) and fertility, and take reasonable measures to improve the planting soil. This is the prerequisite for improving cut flower quality. At present, there are many portable measuring instruments such as pH meters and EC meters that are convenient to use.
How to grow gladiolus
Gladiolus likes fertile, deep sandy soil and requires good drainage. It should not be planted in heavy clay soil or places prone to waterlogging. In Northeast China and North China, summer growth is better than in Guangzhou and Shanghai. In Shanghai, it can overwinter safely in the open field in winter, while in the north the corms must be dug out and stored indoors for winter.
(1) In production, corms are mainly used for planting. In spring, grade the corms by size, soak them for 30 minutes in a 800-fold dilution of 70% thiophanate-methyl powder or a mixture of a 1000-fold dilution of carbendazim and a 1500-fold dilution of captan, then force sprouting at 20 to 25°C, and they can be planted in about 1 week. For varieties with severe virus infection and obvious degeneration, shoot tip virus elimination can be used to rejuvenate the plants.
(2) Conventional gladiolus cultivation refers to cultivation under natural conditions, generally selecting planting corms with a diameter of more than 2.5 cm. Planting methods include ridge planting and bed planting, with a planting depth of 5 to 10 cm. When gladiolus produces its 2nd leaf, this is exactly the time of flower bud differentiation, and it is especially sensitive to environmental factors. If it encounters low temperature and weak light, the number of "blind flowers" increases.
Generally, when preparing the land, apply 6 to 9 kg of nitrogen, 6 to 12 kg of phosphorus, and 7 to 12 kg of potassium per mu. During the entire growing season, topdressing is needed 3 times, namely when 2 to 3 leaves have emerged, when the inflorescence emerges from the leaves, and 15 days after flowering.
(3) For forcing cultivation of gladiolus, the dormancy of the planting corms must first be broken. After the corms are harvested, under natural conditions, dormancy can only be broken after the low-temperature influence from late autumn to early winter. For forcing cultivation, dormancy must be broken artificially, that is, after the corms are harvested, first treat them at a high temperature of 35°C for 15 to 20 days, then treat them at a low temperature of 2 to 3°C for 20 days, and then plant them, after which they can sprout and grow normally.
If flowers are required from January to February, plant in October to November; if planted in December, they will bloom from March to May. That is, from planting to flowering takes 100 to 120 days. For forcing cultivation, the plant and row spacing is 15 cm × 15 cm or 25 cm × 7 cm, with 40 to 60 corms planted per square meter. After planting, the daytime temperature should be kept at 20 to 25°C and the nighttime temperature at about 15°C.
(4) Gladiolus can also be grown by delayed cultivation. After the corms are harvested, store them in a dry cold storage at 3 to 5°C, then plant them again in a greenhouse in July to August of the following year. The management work is the same as for forcing cultivation.
(5) Cut flowers can be harvested 60 to 100 days after planting, with the specific time depending on the variety. The suitable harvest time is when 1 to 5 florets at the lower part of the inflorescence show color. Generally, harvest together with 2 to 3 leaves, and take care not to damage the leaves remaining on the lower stem, so that they can continue to supply nutrients to the new corm and cormels. The harvested flower stems should be graded and packaged, placed in storage at about 4°C, and delivered to consumers within 3 to 7 days. If storage or transport time is too long, quality will decline.