How to Grow Zinnias? A Complete Guide to the Latest Planting Methods

Zinnia is a famous ornamental plant, also known as zinnia, step-by-step high, fireball flower, opposite-leaf chrysanthemum, etc. It is an annual herbaceous plant of the genus Zinnia in the Asteraceae family, native to Mexico, with single-petaled, double-petaled, curled-leaf, wrinkled-leaf and various colors of garden varieties. It is widely cultivated throughout China and sometimes becomes wild. Let us take a look at the planting methods of zinnia together!

Propagation Methods of Zinnia

1. Seed propagation: 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 prepared by mixing 2 parts leaf mold, 1 part river sand, 2 parts peat, and 2 parts perlite. Before sowing, moisten the substrate and sow by dibbling. After sowing, cover with a layer of vermiculite. At a temperature of 21-23°C, germination occurs in 3-5 days.

2. Cutting propagation: Zinnia can also be propagated by cuttings, but cutting seedlings are not as uniform as sown seedlings. Side shoots 10 cm long can be selected for cuttings, generally rooting in 5-7 days. Afterward, cultivation management is the same as for sowing, and they can leave the nursery after 30-45 days.

Planting Methods of Zinnia

1. Plant shaping: If zinnia is not pinched, the plant will have too few side branches and too few flowers. Proper pinching can promote plant dwarfing and increase the number of flowers. When the seedlings grow to 4 leaves, plant them out and pinch, promoting lower branches to grow to form a better plant shape. Start pinching one week after planting out, keep 4 pairs of true leaves, and decide whether to pinch again depending on plant growth and branching.

2. Water and fertilizer management: When planting out, apply 2-3 grams of compound fertilizer to the bottom of the pot. After planting out, drench the roots with 800 times diluted Dexon for disinfection. Within 1 week after planting out, keep the pot soil moist to promote surface root growth. Once the roots grow to the bottom of the pot, start topdressing, fertilizing 2-3 times per week, and also apply 1 calcium fertilizer supplement.

3. Timely pinching: Start pinching 1 week after planting out. After pinching, spray 1 fungicide and apply 1 heavy fertilizer. About two weeks after the last pinching, the plant enters the reproductive stage. Gradually increase phosphorus and potassium fertilizers, such as spraying 1000 times diluted monopotassium phosphate, to promote more and brighter flowers, and correspondingly reduce the amount of nitrogen fertilizer.

4. Temperature and light: Zinnia likes warmth and sunshine, and is not tolerant of severe heat 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, and full-sun exposure can be used directly. If sunlight is insufficient, the plant tends to grow leggy and its resistance is weaker; in addition, flowering will also be affected.

Pest and Disease Control of Zinnia

1. White star disease

[Symptoms] On zinnia leaves, small dark brown spots first appear, then become lesions with dark brown edges and grayish-white centers, 2-4 mm in diameter. They mostly occur on lower leaves. In severe cases, the leaves curl and wither, and the surface of the lesions has dark green mold-like matter.

[Control] Strengthen management, apply sufficient fertilizer, cultivate strong seedlings, protect from rain and shade, strengthen greenhouse ventilation, reduce humidity, and promptly remove diseased residues. In the early stage of the disease, promptly remove diseased leaves, then immediately spray for control. You can use 1:0.5:200 Bordeaux mixture plus 0.1% sulfur powder, or 65% zineb wettable powder 500 times, or 75% chlorothalonil wettable powder 500-800 times, or 50% amobam 800-1000 times.

2. Black spot disease

[Symptoms] Small dark brown spots first appear on the leaves, soon expanding into large irregularly shaped spots, 2-10 mm in diameter, reddish-brown. As the spots expand and increase, the entire leaf turns brown and dries up. On stems, the disease starts from the base of the petiole and develops longitudinally, becoming dark brown elongated streaks. Symptoms on flowers are similar to those on leaves, and soon the petals shrink and dry up.

[Control] Choose well-drained plots for planting. Planting density should be appropriate. Avoid continuous cropping. Seeds must be disinfected before sowing. After autumn, diseased leaves, diseased stems, etc. should be collected and destroyed to eliminate the source of infection for the next year. Keep seeds from disease-free healthy mother plants. Spray with 50% zineb or mancozeb 5000 times diluted solution. When spraying, pay special attention to spraying the leaf backs evenly.

3. Mosaic disease

[Symptoms] It occurs all over the country and often causes plants to become dwarfed and degenerate. In the early stage of the disease, the leaves show slight mottling, and later become light and dark green mottling. Symptoms are more obvious on new leaves.

[Control] Eliminating aphids to prevent disease has a certain controlling effect on zinnia mosaic disease. Attention should also be paid to field sanitation management, and diseased plants should be eradicated to reduce the source of infection.