Detailed Explanation of the Cultivation Techniques and Management Methods for Gongju (Chrysanthemum morifolium)

I. Main Habits and Morphological Characteristics

Gongju is a perennial herbaceous plant with persistent roots. It is sensitive to daylight and is a short-day plant; a short-day stimulus of fewer than 10 hours per day easily induces flower bud formation and blooming. It likes light and dislikes shade; insufficient light will lead to poor plant development and reduced flowering.

Gongju prefers ventilation and coolness, and grows best in fertile, loose, moist, well-drained sandy loam. However, its moisture tolerance is relatively weak; poorly drained soil and excessive humidity will cause 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, which reduces yield and lowers quality.

Gongju flowers like warmth, but they are also relatively cold-tolerant. Its 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 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, the rhizome produces adventitious buds, and 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 Applying Sufficient Base Fertilizer

The Gongju 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, and it can be planted in contiguous fields on flat hills 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, 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 soil that easily accumulates water, and planting in wind gaps. Low-lying waterlogged plots and low-valley plots prone to frost damage are also unsuitable. Sections with heavy mist are unfavorable for producing high-quality chrysanthemums because they affect the quality of harvesting and drying and easily lead to disease. Continuous cropping of chrysanthemums leads to severe disease and poor production, so crop rotation is preferable.

For land used for chrysanthemum planting, 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. Mountain land drains well, so ridges do not need to be made.

III. Cultivating Strong Seedlings

Chrysanthemums that are not raised as seedlings grow weakly and have small, thin flowers. Gongju must be grown from strong seedlings. In production, the commonly used method for propagating Gongju seedlings is division propagation; chrysanthemum plants produced by this method are taller, have more branches, bloom more, and have 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 healthy plants in the soil. Alternatively, 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 healthy 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 expand the speed of chrysanthemum propagation, Gongju can also be propagated by cuttings. The method is as follows: from April to June, cut about 10 cm long shoot tips with 2-4 nodes from new branches sprouting from old plants of the previous year or from plants developed by division; make the lower cut diagonally near a bud or cut it flat, remove the leaves on the lower half, cut the large upper leaves in half, insert them into the seedbed soil to a depth of about one-half, 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 dilute manure water once every 3-5 days to promote seedling growth, and they can be transplanted after one month. Chrysanthemum seedlings produced by this method have large flowers. In addition, when the climate is damp and cloudy, healthy branches can also be directly cut into the field to grow into seedlings.

IV. Timely Transplanting

When using division propagation, divide and transplant in mid-to-late April, and choose strong flower seedlings that are free of pests and diseases and 7-8 cun tall. When planting seedlings, pay attention to weather changes when choosing the time; transplanting on cloudy days after rain is suitable and 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. When transplanting, the tops of the seedlings can be pinched off to promote recovery and branch growth. If the soil is not moist enough and the weather is dry during transplanting, it is necessary to water to settle the roots. 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 the number of flowers, encourage thick main stems, 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 a sunny day. After pruning, the plant sends out 5-6 new branches. The second topping is done when the newly developed branches are about 6 cm long, around mid-June; after the second topping, the plant sends out 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 thin and 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 timely and appropriate according to plant growth. In addition, overly dense branches and thin, weak branches should be pruned in time to improve nutrition and ventilation and light conditions and promote more and larger flowers. In plots where viruses occur, diseased plants must first be removed to avoid transmission by pruning shears and fingernails.

VI. Cultivation, Weeding, and Earthing Up Around the Roots

During the growth period, Gongju requires frequent hoeing and cultivation, that is, manual weeding, to achieve the purposes of weed control and soil loosening. Generally, cultivate and weed 4-5 times, namely once in early May, once in early June, once in early August, and once in early September. Keep early cultivation shallow and later cultivation deeper to avoid damaging the chrysanthemum roots. During later cultivation and weeding, earth up around the roots or set up supports each time to protect the root system and prevent lodging. Cultivation is not suitable in July; grass can be cut and used as mulch, which both prevents water evaporation and suppresses weeds.

VII. Fertilizer and Water Management and Staking to Prevent Lodging

Chrysanthemum growth and flowering require a large amount of fertilizer, so fertilizer should be added in a timely manner according to the growth needs of chrysanthemums. Fertilization time is generally after weeding. From May to July, apply manure water 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 combined 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 have a large fertilizer requirement, so appropriately increase nitrogen fertilizer, and cake fertilizer, human and livestock manure, and a small amount of urea can be applied to promote budding and flowering. After flower buds form, foliar feeding can also be done with 0.3% urea plus 0.2% potassium dihydrogen phosphate, or Tianyuan liquid fertilizer.