How to grow Gongju chrysanthemums? A detailed guide to the cultivation techniques for perennial herbaceous Gongju chrysanthemums
I. Main habits and morphological characteristics
Gongju chrysanthemum is a perennial herbaceous plant. It is sensitive to day length and is a short-day plant; stimulation by a short photoperiod of less than 10 hours per day easily induces bud formation and flowering. It likes light and dislikes shade; insufficient light will lead to poor plant development and reduced flowering.
Gongju chrysanthemum likes ventilation and coolness, and grows best in fertile, loose, moist, well-drained sandy loam. However, its tolerance for moisture is relatively weak; poor soil drainage and excessive humidity will lead to poor growth or even root rot and death. If it is too dry, there will be few branches and slow growth; especially when water is lacking during the flowering period, the leaves become smaller and the number of flowers decreases, reducing both yield and quality.
Gongju chrysanthemum flowers like warmth, but they are also relatively cold-tolerant. Their roots overwinter underground and can withstand low temperatures of minus 10-15°C. The flowers can withstand light frost, but heavy frost will greatly reduce yield and lower quality.
Gongju chrysanthemum branches are fragile, and under natural growth they are easily blown over or broken by wind. The plant height is generally 60-100 cm. The root system spreads horizontally in the topsoil, and the rhizome produces adventitious buds. Flowers are borne at the tips of branches or in leaf axils. The flower color is white, and it is a small-flowered chrysanthemum with flat petals.
II. Land selection, land preparation, and application of sufficient base fertilizer
The Gongju chrysanthemum plot should be flat land with no pollution sources and where chrysanthemums have not been planted before. Our city has a wide suitable range for planting Gongju chrysanthemum, and it can be planted in continuous tracts on flat land and gentle slopes, or intercropped in gaps in tea, mulberry, and orchard land as well as grain and oil cropland. However, land selection must be based on the habits of Gongju chrysanthemum, seeking advantages and avoiding disadvantages. It requires shelter from wind and facing the sun, fertile soil, and convenient drainage and irrigation. Avoid shaded plots, compacted and heavy clay soil prone to water accumulation, and planting at wind gaps. Low-lying waterlogged plots and low-valley plots prone to frost damage should also not be selected. Sections with heavy fog are unfavorable for producing high-quality chrysanthemums because they affect harvesting and roasting quality and make disease more likely. Chrysanthemums suffer severe disease under continuous cropping and grow poorly, so crop rotation is preferable.
For land used for planting chrysanthemums, it is best to deep plow in winter (25 cm), turn the soil in spring, and apply sufficient base fertilizer. According to soil fertility, apply 1000-1500 kg of organic fertilizer such as barnyard manure or compost per mu, 50 kg of phosphate fertilizer, and about 100 kg of cake fertilizer. On flat land, make ridges and dig drainage ditches well, with a ridge spacing of 30-40 cm and a ridge width of 70-80 cm. In mountainous areas with better drainage, there is no need to make ridges.
III. Cultivating strong seedlings
Chrysanthemums that are not raised as seedlings grow weakly and have small flowers, so Gongju chrysanthemum must be grown from strong seedlings. In production, the commonly used method for propagating Gongju chrysanthemum seedlings is division propagation; chrysanthemum plants produced by this method are taller, have more branches, more flowers, and relatively larger flowers.
(1) Division propagation method: After the chrysanthemum harvest is completed, cut off all the old stems of the chrysanthemum level with the ground, and leave the roots of robust plants in the soil. Or dig up the roots and bury them together in a selected piece of fertile, well-drained sandy loam. Loosen the soil, apply winter fertilizer, and pay attention to pest and disease control to promote robust growth of the chrysanthemum seedlings. When the seedlings grow to 5-8 cun tall, they can be divided and transplanted.
(2) Cutting propagation method
To increase the propagation speed of chrysanthemums, Gongju chrysanthemum can also be propagated by cuttings. The method is: from April to June, cut about 10 cm long branch tips with 2-4 nodes from new branches sprouting from old plants of the previous year or from plants developed by division. Cut the lower cut diagonally or straight near a bud, remove the leaves on the lower half, cut off half of the large upper leaves, insert about one-half into the seedbed soil, space each plant 10 cm apart, water thoroughly, and provide half shade. After the dew dries each morning, spray with an appropriate amount of clean water; the amount of water should not be too much. After half a month, they will take root and sprout. After that, apply a light manure slurry once every 3-5 days to promote seedling growth, and they can be transplanted after one month. Chrysanthemum seedlings raised by this method have large flowers. In addition, when the climate is cloudy and humid, robust branches can also be directly cut into the field to become seedlings.
IV. Timely transplanting
When using division propagation, divide and transplant in mid-to-late April, and choose strong flowering seedlings 7-8 cun tall with no pests or diseases. When planting seedlings, pay attention to weather changes when choosing the time; transplanting after rain on cloudy days gives a high survival rate. Transplanting when the soil is dry and under clear skies with strong sun is not suitable. Plant 3000-4000 plants per mu, with a row spacing of 40 cm and a plant spacing of 33 cm, and plant 1-2 plants per hole. Using a reasonably arranged wide-narrow row planting pattern is beneficial for ventilation and light penetration in the later growth stage of the chrysanthemum garden and facilitates field operations. During transplanting, the tops of the seedlings can be removed to promote recovery and branch growth. If the soil is not moist enough and the weather is dry during transplanting, root-setting water must be applied. If there are few seedlings, they can be planted sparsely and then propagated by layering to increase density; layering can be repeated until the number of seedlings is sufficient.
V. Topping and pruning
To promote branching, increase flower number, make the main stem thick and strong, reduce lodging, and improve yield and quality, chrysanthemums must be topped and pruned 3-4 times. The first time is in mid-May on a sunny day, leaving about 5 cm at the base and cutting off all the upper part; note that pruning should be done on sunny days. After pruning, the plant produces 5-6 new branches. The second topping is done when the newly grown branches are about 6 cm long, around mid-June; after the second topping, the plant produces 11-12 new branches. The third topping is from late June to early July. Vigorous plants can be topped a fourth time, but topping work must be finished before the end of July. The number of toppings should not be too many either, otherwise there will be too many branches, the plants will not be strong, the flower heads will be small, and yield and quality will decline. If not pruned or pruned only once, there will be too few branches and reduced flowering. The timing and number of toppings should be based on plant growth and done at the right time and in the right amount. In addition, overly dense branches and thin, weak branches should be pruned promptly to improve nutrition and ventilation and light penetration, promoting more and larger flowers. In plots where viruses occur, diseased plants must first be removed to avoid transmission by pruning shears and fingernails.
VI. Intertillage, weeding, and earthing up around the roots
During the growth period, Gongju chrysanthemum must be hoed and intertilled frequently, that is, manual weeding, to achieve both weed control and soil loosening. Generally, intertillage and weeding are done 4-5 times, namely once in early May, once in early June, once in early August, and once in early September. Keep the early intertillage shallow and the later intertillage deeper to avoid damaging the chrysanthemum roots. During later intertillage and weeding, earth up around the roots or set up supports each time to protect the root system and prevent lodging. Intertillage is not suitable in July; instead, cut grass and mulch to prevent both water evaporation and weeds.
VII. Fertilizer and water management and staking to prevent lodging
The growth and flowering of chrysanthemums require a large amount of fertilizer, so fertilizers must be added promptly according to the growth needs of chrysanthemums. Fertilization time is generally after weeding. From May to July, apply manure slurry 3-5 times to promote strong seedlings and plants. From late August to early September, appropriately increase the application of phosphorus and potassium fertilizers (100-150 kg per mu, which can be applied with 0.5% urea), and apply the next round of human and livestock manure (1000 kg per mu) to promote flower bud differentiation. In October, chrysanthemums need a large amount of fertilizer, so appropriately increase nitrogen fertilizer; cake fertilizer, human and livestock manure, and a small amount of urea can be applied to promote budding and flowering. After flower buds form, 0.3% urea plus 0.2% monopotassium phosphate, or Tianyuan liquid fertilizer, can also be used for foliar spraying.