Key Points of Zinnia Seed Propagation Explained in Detail
Zinnias have high ornamental value, but since zinnia is an annual herbaceous plant, artificial propagation of zinnias is the only way to meet market demand. Zinnias are generally propagated by sowing. The editor will give you a detailed introduction to the sowing methods of zinnias and the precautions during the sowing process.
Zinnia
The suitable temperature for zinnia seed germination is 20-25°C, generally germinating in 7-10 days, and flowering about 70 days after sowing. Transplant seedlings when 2-3 true leaves appear, pinch when 4-5 leaves appear, and after 2-3 transplants they can be planted in place.
In North China, sowing is mostly done in open ground in mid to late April, germinating in about a week. Transplant or thin when 2-3 true leaves appear. The planting spacing in the field is determined by the height of the variety, ranging from 15-40 cm. For pot cultivation, wait until after pinching, then transplant into pots; the pots can be turned once. For dwarf varieties grown in pots, pinch repeatedly to promote side branches and form a full bushy plant. For flowers needed for "May Day," sow indoors in early February, divide seedlings into pots in late March, and remove from pots for planting in late April. Topdressing should be mainly phosphorus and potassium fertilizer.
Seed saving should be done when the outer ray florets begin to dry up and the middle ray florets begin to lose color. Cut off the flower heads, dry them in the sun, remove impurities, and store. Zinnias have a long flowering period, and in the later stage the plants will decline in vigor, with messy stems and leaves and smaller flowers. Therefore, flowers for autumn flower beds should be sown again in summer, with pinching 1-2 times. Cutting propagation can be done after mid-June, cutting side branches for cuttings, with shading and rain protection.
Before sowing, the soil and seeds must undergo strict disinfection treatment to prevent pests and diseases during the growing period. Sowing can be done from early April to late June. For seed disinfection, soak the seeds in 1% potassium permanganate solution for 30 minutes. The substrate is mixed from 2 parts leaf mold, 1 part river sand, 2 parts peat, and 2 parts perlite. It can be disinfected with 0.05% potassium permanganate or 1000 times formalin. The soil can be treated by high-temperature fumigation to kill pathogens, pests, and weed seeds in it.
Before sowing, moisten the substrate and sow by dibbling. Zinnia is a light-avoiding flower seed, so after sowing it must be covered with a layer of vermiculite. At a temperature of 21-23°C, germination occurs in 3-5 days. Light is not needed during the germination period. After germination, the seedbed should maintain 50%-60% moisture content, not too wet, to avoid root rot or damping-off disease.
The sowing time depends on the desired flowering time. Generally, sow in a greenhouse 2-3 months in advance. Direct sowing in open ground should be done after the severe cold of early spring, otherwise the seedlings will develop poorly; if used for autumn flower beds, it is best to sow in summer. Zinnia seeds are light-avoiding seeds, so after sowing the soil covering should be thick and dense to increase the germination rate. Carry out sowing in March-April in spring. Each gram contains 120-130 seeds. The suitable germination temperature is 21-25°C. After sowing, germination occurs in 7-10 days, with a germination rate of 60%.
From sowing to flowering varies by variety, from 45-75 days. Spring sowing is done in March-April, transplant when 4-5 leaves appear, with a plant spacing of 10 cm. Plant in place in early June, with a spacing of 30×30 cm. During the growing period, apply 10-fold diluted human manure liquid once every 10 days. Flowers bloom from July until frost. Zinnias can also be propagated by side-branch cuttings in summer, but because the temperature is too high and there are many showers, attention should be paid to protection and shading.
Key Points for Cultivation and Care of Potted Zinnias
Zinnia, also known as (step-by-step high), (opposite-leaf plum), and (five-color plum), is an annual herbaceous flower of the genus Zinnia in the Asteraceae family. Plant height ranges from 40 cm to 120 cm. The stems are erect, covered with short hairs, and rough on the surface. Leaves are opposite, ovate to elliptical, entire, covered with short bristles, and the leaf base clasps the stem. The flower head is 5 cm to 15 cm in diameter, borne at the top of the branches, with a long pedicel. The ray florets are in many rows, with petals obovate, the apex slightly rolled backward, in colors such as white, yellow, red, pink, purple, green, and orange. The tubular florets are concentrated in the center of the flower disk, with the corolla apex 5-lobed, yellow to orange-yellow, and the style 2-lobed. The involucre of the inflorescence is multi-layered and bell-shaped, united at the base. The ray florets can also set seed; their achenes are broadly ovate to bottle-shaped, tapering at the apex, slightly concave in the middle. The achenes produced by the tubular florets are elliptical, flat and small. The fruits mature successively from August to October. Seeds have a lifespan of 3 years, and the flowering period is from June to October.After long-term artificial hybridization and selection, zinnias have many cultivated types, which can be broadly divided into three categories: large-flowered tall-stem type, medium-flowered medium-stem type, and small-flowered clustered type. The large-flowered tall-stem type has a plant height of 90 cm to 120 cm, few branches, and terminal flower heads up to 12 cm to 15 cm in diameter; tetraploid varieties have flower diameters of 15 cm to 18 cm. The medium-flowered medium-stem type has a plant height of about 50 cm to 60 cm, more branches, flower heads about 6 cm to 8 cm in diameter, with the top slightly flattened, and the whole flower head approximately oblate-spherical. The small-flowered clustered type has a plant height of only 40 cm, many branches, and more flowers per plant, but the flower head diameter is small, only 3 cm to 5 cm. The ray florets are flat and not rolled back, and the flower head looks spherical.
In the 1970s, a new dwarf type was bred, with branches spreading in a semicircular shape, flower diameter 7 cm to 8 cm, and plant height below 30 cm. The shortest mini type is only 20 cm tall with a flower diameter of about 4 cm. There are also dwarf large-flowered varieties.
Zinnia is native to Mexico and other places, and is now widely cultivated around the world. It is robust, highly adaptable, has a relatively deep root system, and hard stems that are not easy to lodge. It likes sunlight, and under long-day conditions the ray florets increase. It likes warmth, is not cold-tolerant, tolerates poor soil, tolerates drought, avoids continuous cropping, and fears damp heat. When planted in the ground, it grows well in fertile areas with deep soil layers. For pot cultivation, sandy culture soil containing humus, loose and fertile, and well-drained is best.
Propagation is usually by sowing. The suitable germination temperature is 20°C to 25°C, germinating in 7 to 10 days. Seed germination requires dark conditions, so after sowing the seeds must be covered with soil and sealed tightly. Open-ground sowing time should not be too early. If the temperature drops below 15°C after emergence, the seedlings will stop growing and thereafter will always grow poorly, forming "small old seedlings." When seedlings are 5 cm to 8 cm tall, they should be divided and transplanted once. In late May they can be transplanted to flower beds to be planted in place. After mid-June, side branches can also be taken for cutting propagation. Pay attention to shading and rain protection to avoid infection and rot of the cuttings.
For potted zinnias, it is best to choose new dwarf types and dwarf large-flowered varieties. They can be sown in pots in a greenhouse in early February, divided and transplanted into pots with an inner diameter of 10 cm in mid-March, one plant per pot, and then repotted into 18 cm pots in early April to be planted in place. With stable room temperature, sufficient light, air circulation, and moderate water and fertilizer, they can bloom and be displayed by "May Day."
Analysis of Zinnia Planting Techniques and Key Points
Analysis of Zinnia Planting Techniques and Key Points
[Common Questions] How are zinnias planted? What are the key points?
[Expert Answer]
Cultivation Techniques of Zinnia
Zinnia is a short-day plant, so the flowering period needs to be regulated by controlling day length. When day length is longer than 14 hours, flowering will be delayed, taking about 70 days from sowing to flowering, and at this time the ray florets will increase noticeably; when day length is shorter than 12 hours, flowering can be advanced, taking only 60 days from sowing to flowering, and at this time there will be more tubular florets. In addition, the flowering period can also be controlled by adjusting the sowing period and pinching time.
During sowing, zinnia requires a well-drained, loose, and fertile soil environment. The usual germination temperature is 21-22°C. During germination, soil covering is required, and germination occurs in 2-5 days. During growth, the day temperature should be maintained at 18°C and the night temperature should reach 21°C. From sowing to flowering, the time required is generally 9-10 weeks. Also worth noting is that zinnia avoids continuous cropping and should be rotated in a timely manner.
Zinnias are prone to excessive vegetative growth in the later growth stage. The following measures are usually taken to control it: first, appropriately lower the temperature; second, ensure sufficient nutritional area by increasing plant and row spacing; third, pinch in time to promote axillary bud growth. The specific operation is generally carried out when the plant height is about 10 cm, leaving 2 to 4 pairs of true leaves before pinching. To keep plants low and still flowering, a dwarfing agent is often sprayed when the axillary buds grow to about 3 cm after pinching. Seedlings that have not grown excessively can be cultivated in open ground; if it is necessary to limit their growth height, pinching treatment should also be carried out.
Zinnia has strong growth vigor and likes a warm, dry, and sunny environment, and can also tolerate semi-shade. The suitable growth temperature is 20-25°C. It is not tolerant of severe heat; when the temperature is above 35°C, growth weakens noticeably, flowering is sparse, and the flowers are also smaller. It is a short-day plant. Under long-day conditions (14 hours of light per day), plant height increases and there are more ray florets; under short-day conditions (9 hours of light per day), the ray florets become smaller and the tubular florets increase. It is highly adaptable and not choosy about soil, but grows best in deep, fertile soil with good drainage. In summer with much rain or poor soil drainage, the plants become slender and the flowers become smaller. It avoids continuous cropping.
Zinnia is mainly propagated by seeds and can also be propagated by cuttings. Seed propagation is suitable for spring sowing, generally carried out in mid to late April, with a suitable germination temperature of 15-20°C. Its seeds are light-avoiding, so after sowing they should be covered with soil, watered, and kept moist. They germinate and emerge after about 1 week. The germination rate is generally about 60%. From Xiaoman to Xiazhi, in combination with pinching and pruning, select robust branches, cut 10-15 cm long tender shoots as cuttings, remove the lower leaves, keep the upper two leaves, insert them into fine river sand, spray water frequently, and provide appropriate shade. They can root after about 2 weeks.
After planting and survival, fertilization during the seedling-growing period does not need to be too frequent; generally apply liquid fertilizer once a month. Near the flowering period, more topdressing can be applied, once every 5-7 days, until full bloom. When the seedlings reach 10 cm in height, leave 2 pairs of leaves and pinch off the top to promote the growth of side branches. When the side branches grow to 2-3 pairs of leaves, leave 2 pairs of leaves and pinch a second time. Doing this can make the plant shape full and produce abundant flowers. After spring sowing, they can bloom in 70 days. Zinnia flowers at the top of the branches. When the flowers fade, promptly cut off the faded flowers from the base of the flower stem while leaving 2 pairs of leaves, so as to induce new shoots from the leaf axils at the cut. After pruning, water frequently and apply topdressing 2-3 times, which can extend the flowering date to before frost. The first batch of seeds that mature before the rainy season is of better quality and should be harvested and saved in time.
Sown seedlings are planted in 10-12 cm pots when they have 4-6 leaves. Zinnia has few lateral roots, so take care to damage the lateral roots as little as possible when transplanting. When the seedlings are 10 cm tall, pinch to encourage more side branches. In production, to dwarf the plants, spray with 0.5% B-Nine 2 weeks after pinching, with remarkable results. Growth regulators can also be used to regulate the flowering period. Spraying seedlings with 0.25%-0.4% B-Nine solution can advance flowering and make the flowers compact; if 0.4%-0.8% B-Nine or chlormequat is used and sprayed 2-4 times, flowering will be delayed. During the seedling stage, fertilize once every half month, and apply phosphorus and potassium fertilizer 2 more times before the flower buds form. Or use "Huiyou" 20-20-20 general-purpose fertilizer. If seeds are not to be kept after flowering, promptly remove the faded flowers to promote the growth of new side branches from the leaf axils and bloom again. Seed-producing plants must be isolated to prevent crossbreeding among varieties and affect seed quality.
Key points:
Zinnia likes warmth and sunlight, and is not tolerant of severe heat, high temperatures, or severe cold. The suitable growth temperature is 18-20°C during the day and 15-16°C at night. Growth is especially rapid in summer.
Full-sunlight methods can be used directly, with direct sunlight. If sunlight is insufficient, the plants are prone to excessive vegetative growth and have weaker resistance; in addition, flowering will also be affected.
Because the light requirement is high, water evaporates very easily, so appropriate humidity must be maintained frequently. In summer, water can be given every day.
The planting density is 12—18 plants per square meter. Zinnia likes a slightly moist but somewhat dry soil environment and avoids waterlogged conditions. In addition to applying an appropriate amount of chicken manure as base fertilizer when planting, during the vigorous growth stage a dilute liquid fertilizer should also be applied once a week. It is a crop that likes nitrate nitrogen, so do not apply fertilizers such as ammonium sulfate and ammonium bicarbonate that are ammonium nitrogen fertilizers. Zinnia likes sufficient sunlight and avoids shaded environments. Maintaining ventilation in the environment can prevent excessive vegetative growth and reduce the occurrence of powdery mildew. Zinnia likes warmth and is not cold-tolerant. Its suitable growth temperature is 20—30°C. After frost in autumn, the plants gradually die.
Editor's comments:Because zinnias have a beautiful plant shape, brilliant flower colors, and a long flowering period, they are often used in flower beds and flower borders. Today the editor introduces zinnia planting techniques in the hope that it will be helpful to everyone.