Detailed Explanation of Key Techniques for High-Efficiency Marigold Cultivation
Marigolds have colorful and vibrant flowers, bloom profusely, have a long flowering period, and are easy to cultivate, making them an excellent landscaping and street greening material. Marigolds prefer a warm, sunny environment and can also tolerate early frost, still growing at short-term low temperatures of 2-3°C. They are not demanding about soil, tolerate transplanting, and produce abundant, colorful flowers. They grow rapidly, are easy to cultivate, and have relatively few pests and diseases.
Seedling Raising and Planting
Marigolds are mostly propagated from seed, and can also be propagated by cuttings. The former method is mostly used for large-area planting, while the latter is often used for cultivating rare varieties.
Seed sowing for seedling raising can be done in all four seasons. Usually, spring sowing produces autumn flowers, and summer sowing produces autumn and winter flowers. The seeds germinate easily and can self-sow and reproduce. From late March to early April, prepare the soil and make beds, then cover with soil at a thickness of 0.8 cm after sowing. Then water with a fine-nozzle watering can to keep the soil moist. At a temperature of 20-21°C, the seeds germinate and emerge 1 week after sowing, and in about half a month the leaves reach 7, at which point they can be transplanted. The optimal temperature for seedling growth is 15°C. When the seedlings are 10-13 cm tall, they can be planted out at a spacing of 30-35 cm. Early-maturing varieties have a short vegetative growth period, flowering in about 40 days, while late-maturing varieties flower in about 90 days, with a flowering period of 2 months.
During the growth period in May-June, cut healthy young shoots with 3-4 nodes, 6-10 cm long, and insert them under a shade frame for cutting propagation. The substrate is washed river sand or garden soil. The cutting depth is 2-3 cm, and the soil should be kept moist. Roots form after 2 weeks, and after 3 weeks they can leave the nursery for planting out, flowering in about 1 month. For large-scale cuttings, use the full-light misting method, and perlite can be used as the substrate. Because misting increases air humidity, the cuttings do not need shading during the day after insertion, and more leaves can be left on the cuttings than in conventional seedling raising. Roots form in about 1 week, and then transplanting is carried out.
Field Management
If marigolds are planted in sunny, loose and fertile soil, no additional fertilization is needed after planting. If the soil is poor, during peak growth periods such as the bud stage and flowering stage, spray the leaves 2-3 times with 0.3% urea solution, adding 0.5% potassium dihydrogen phosphate. Because they are relatively drought-tolerant, apart from watering during especially dry summer periods, generally no watering is needed.
Shaping and Pruning
Pinching off side buds at the seedling stage favors top bud growth and elongation of flower stalks, making them suitable for flower bed arrangements. In summer, plants tend to grow excessively, so timely pruning is needed to control height. After pinching off the top bud, plants are shorter, flower earlier, and the flowering period is easier to control. Because the flowering period is long, plants tend to lodge in the later growth stage, and branches and leaves tend to wither and age, so overly dense stems and leaves and spent flowers should be promptly thinned out. Tall and medium-stemmed varieties must be supported with stakes and double wire to hold up the stems and prevent lodging from wind.
Pest Control
When the hot summer heat arrives, and there is little rain and dry air, red spider mites are prone to causing damage. In addition to choosing well-ventilated plots, it is advisable to spray efficient, low-toxicity pesticides early for prevention and control.