How to grow ornamental sunflowers? A detailed guide to planting methods
What varieties of ornamental sunflowers are there? How do you grow ornamental sunflowers? We ask experienced gardeners to share their knowledge. Ornamental sunflowers have graceful plant forms, dense foliage and branches, and large, brilliantly colored flowers. They can be used as potted flowers, cut flowers and garden flowers. As a result, more and more tourist attractions, farm stays, orchards...
What varieties of ornamental sunflowers are there?How do you grow ornamental sunflowers? We ask experienced gardeners to share their knowledgeOrnamental sunflowers have graceful plant forms, dense foliage and branches, and large, brilliantly colored flowers. They can be used as potted flowers, cut flowers and garden flowers. As a result, more and more tourist attractions, farm stays and orchards are growing them, so Zhongdiwang has compiled the growing methods for ornamental sunflowers, listed in detail below for readers' reference.
I. Variety selection for ornamental sunflowers:
1. Because ornamental sunflowers vary by variety, plant height differs greatly: the short ones are only 20-30cm, while the tall ones can reach about 2-3m, and some have thick, sturdy underground rhizomes.
The whole ornamental sunflower plant is covered in stiff hairs, the stem is hollow, and the leaf shape is not very different from that of the common sunflower. The leaves are alternate, with long petioles, ovate, green, with pointed tips, and the leaf margins are sometimes serrated. The capitulum, commonly called the flower disc, is borne at the top of the stem; cut-flower varieties often have multiple branches, forming multiple flower discs. Flower discs come in 3 shapes: raised, flat and sunken. The diameter of the flower disc varies by variety from 10cm to more than 20cm. The flower disc has ray florets and tubular florets; the ray florets are in 1 to 3 layers, borne on the edge of the disc, and are sterile florets whose role is to lure insects to come collect nectar and pollinate. Ray florets come in yellow, creamy white, orange, reddish brown, purple-black and other colors, and the petals may be single or double. The tubular florets are located inside the ray florets and are bisexual florets.
2. The flowering period of ornamental sunflowers varies greatly depending on sowing time and management practices. Under conventional field planting, they generally bloom from June to September, and the seeds mature in mid-September.
There are many varieties of ornamental sunflowers, including pot types, cut-flower types and flowerbed types, and varieties for different uses should be chosen according to need. When grown as cut flowers, cut-flower varieties should be selected; currently the commonly grown varieties are pollen-free F1 hybrids, such as 'Golden 08', the double-flowered 'Golden Auspicious' and 'Three Suns Bring Prosperity'. Among dwarf sunflowers, varieties such as 'Big Smile', 'Teddy Bear', 'Red Pula' and 'Valentine' are short in stature and generally bloom 50 to 55 days after sowing, making them suitable for pots and flowerbeds. Some cut-flower varieties such as 'Sunshine', 'Giant Autumn', 'Italian White', 'Orange Sun' and 'Holiday' can also be dwarfed with growth regulators for enjoyment as potted flowers.
Ornamental sunflowers like warmth, are slightly drought tolerant, and require a growing environment with plenty of sunlight.
II. Growing environment for ornamental sunflowers:
Ornamental sunflowers are moderate in size and can be planted in the ground in front of windows, along walls or beside fences in small courtyards, or grown in pots to decorate balconies, well-lit living rooms, bedrooms and other places. Potted plants accenting a small home courtyard or windowsill create a thriving atmosphere. Used in mass plantings in public places and to decorate scenic spots, they can present a festive and lively scene.
Because their flowers are golden yellow, their flowering period is long, they last a long time in the vase, and their stems are upright, they symbolize good fortune and have a distinctive charm as cut flowers. Used in flower baskets and bouquet arrangements, they can rival summer chrysanthemum varieties and are a new type of cut flower worth promoting.
At present, large-scale open-field sowing has begun in places such as Henan and Guangdong in China. In places such as Panyu in Guangdong and Zhengzhou in Henan, there are already "Million Sunflower Gardens" with 1 million plants.
III. Seedling raising time, methods and management methods for ornamental sunflowers:
1. Seedling raising methods for ornamental sunflowers:
Ornamental sunflowers are mainly propagated by sowing, and sowing can be done throughout the year as needed. Depending on the use, methods such as seedbed seedling raising, direct sowing in the field and plug-tray sowing are used. When grown for cut flower production, plug-tray sowing is often used.
2. Sowing quantity for ornamental sunflowers:
Ornamental sunflower seeds vary greatly by variety: large seeds number 25-50 per gram, while small ones number about 110 per gram. The optimum germination temperature is 21°C-25°C. In the open field, hole sowing is commonly used, while sowing trays use spot sowing; germination occurs 7-10 days after sowing, with a germination rate of 80%-90%.
3. Sowing time for ornamental sunflowers:
The specific sowing time for ornamental sunflowers is determined by the time the flowers are needed, and sowing can be done throughout the year according to application needs. Generally, sowing from January to April or from September to October results in flowering 60-70 days after sowing; sowing from May to August or from November to December results in flowering 70-80 days after sowing. The time required differs among varieties. If sowing from November to December, attention must be paid to keeping warm. For dwarf potted types, it generally takes 50-60 days from sowing to flowering.
4. Sowing methods for ornamental sunflowers:
When using plug-tray sowing to raise seedlings, sow in relatively deep seedling trays; the substrate should be loose, have good water retention and be sterile, generally using a mix of peat, potting soil and sand as the sowing substrate. When sowing, first fill the seedling trays with the prepared nutrient soil, water thoroughly until the bottom is soaked, and begin sowing only after the water has drained away. Sow one seed per cell, cover after sowing, and water thoroughly to keep the substrate moist. After sowing, cover with 2cm of fine soil, press firm, cover with a layer of plastic film, and place in a dark place until emergence. The germination temperature is 25°C, with germination in 3 to 4 days. The spacing between seeds should be about 2cm; do not sow too densely, otherwise seedlings tend to emerge "with the shell attached".
5. Seedling management methods for ornamental sunflowers:
After ornamental sunflowers emerge, pay attention to ventilation and cooling, control humidity, and gradually expose them to light. When the seedlings grow to 5-6cm about 2 weeks after sowing, they can be transplanted. After emergence, seedlings should be pricked out promptly and moved into 10cm×10cm nutrient pots to be cared for until planting out. During this period, pay attention to the amount of watering to avoid spindly overgrowth.
For direct sowing in the field, the sowing spacing for dwarf varieties is 12cm×12cm; for large-flowered and large-plant types, the spacing between plants and rows should be appropriately increased, with 1 to 2 seeds per hole. In soil with high residual fertilizer, sow at a spacing of 10cm×10cm.
During seedling raising, the substrate should not be too wet, and ventilation should be strengthened and light increased to prevent the spread of fungal diseases. When raising seedlings in hot, rainy seasons, mancozeb and metalaxyl can be sprayed regularly at 1000 times dilution. After the cotyledons appear, spray with chlorothalonil or thiophanate-methyl at 1000 times dilution once a week, for 2-3 consecutive applications, to prevent damping-off.
IV. Transplanting time, methods and management methods for ornamental sunflowers:
1. Transplanting time for ornamental sunflowers:
The optimum soil temperature for transplanting ornamental sunflowers is 15°C. In frost-free areas in winter, they can grow in the field year-round, while in cold winter areas they need to be cultivated under protection in a greenhouse. If planted in highly fertile fields, planting density needs to be increased to limit excessive plant growth and overly large flowers. Sometimes the plant and row spacing should be adjusted according to the soil's own fertility and the market's requirements for stem thickness. When planting out, apply sufficient base fertilizer at the bottom of the pot; when digging up seedlings, carry as much soil as possible and damage the roots as little as possible so the plants recover quickly. Stop watering before planting out, and water thoroughly once promptly after planting out, which helps promote new roots.
2. Transplanting methods for ornamental sunflowers:
Sunflowers are not demanding about soil and can grow well in all kinds of soil. The most suitable soil is sandy loam or loam with a pH of 5.8 to 6.5. Good soil permeability is crucial for the growth of sunflowers. The soil should be plowed and loosened before sterilization and sowing to improve soil structure and drainage.
The field plot for planting ornamental sunflowers should be prepared in the autumn of the previous year, and the soil should preferably be loose, fertile loam. An appropriate amount of decomposed farmyard compost should be applied to the planting soil as base fertilizer, at 2000kg of organic fertilizer per mu, plus some quick-acting chemical fertilizers such as urea and diammonium phosphate, at 10kg per mu.
For potted ornamental sunflowers, choose flower pots with a diameter of 10-15cm according to the size of the above-ground crown. The potting soil should preferably be a mix of fertile garden soil, leaf mold and coarse sand, with a small amount of decomposed livestock and poultry manure mixed in as base fertilizer.
Cut-flower sunflower cultivation avoids continuous cropping. For open-field cultivation, the land must be rotated after 1 to 2 crops, and for potted plants, soil sterilization must be done well to prevent the breeding of pests and diseases.
3. Water management for ornamental sunflowers:
Ornamental sunflowers have very different water requirements at different growth stages. In open-field cultivation, the root system is relatively well developed and drought tolerant, so little watering is needed in spring; only when temperatures rise in early summer and water evaporation increases is supplementary watering needed. From sowing to bud appearance, they are relatively drought resistant and need little water. Moreover, moderate drought is good for root growth and enhances drought resistance. During the bud stage, water should be controlled appropriately, but under conditions of strong light and high temperatures, because the plants are tall, the leaves are luxuriant and water consumption is high, watering should be done promptly to prevent leaf wilting, which affects normal plant growth and leads to reduced cut-flower quality. From bud appearance to flowering is the peak water-demand period; water shortage during this period has a great impact on flower yield, and if it is too dry, irrigation is needed as a supplement.
For potted ornamental sunflowers, since the plant is large and the pot is small, watering must be timely during the growing period, otherwise the leaves easily dehydrate and wilt. However, do not water too much; overly wet potting soil will cause the leaves to turn yellow. At sowing and transplanting, the soil should be moist, and afterward it should be moderately moist. The seedling stage requires sufficient water, keeping the soil moist at all times; in early summer when the temperature rises to 25°C-28°C, evaporation is greater, so the amount of water given should be appropriately increased.
4. Fertilizing ornamental sunflowers:
Potted sunflowers should be given a dilute decomposed liquid fertilizer or compound fertilizer once every 7-10 days. At the seedling stage, nitrogen fertilizer is mainly used to promote lush foliage and branches; after bud appearance, more phosphorus and potassium fertilizer should be applied to provide sufficient nutrition, so that the buds grow robustly and flowering is favored. A fertigation drip system mixing fertilizer and water can also be used, applying liquid fertilizer according to leaf color, as long as the bottom leaves do not turn yellow from lack of fertilizer. Excess fertilizer should also be avoided, and the use of liquid fertilizer should be controlled after bud appearance. When grown as cut flowers in pots, fertilizer must not be applied too much, lest the flower heads become too large and the stems too thick, which is unfavorable for vase life.
If the soil is fertile, field-grown sunflowers may not need fertilizing. If soil fertility is too poor, apply mainly nitrogen fertilizer in the early stage, and add phosphorus and potassium fertilizer during the bud stage. Fertilize once every 20 days during the growing period, but 2 to 3 applications of dilute phosphorus and potassium fertilizer should be given before flowering.
5. Temperature requirements for ornamental sunflowers:
Temperature and light: Sunflowers have strong adaptability to temperature and are warmth-loving yet cold-tolerant plants. Sunflower seeds are highly tolerant of low temperatures; when the soil temperature stabilizes above 2°C, the seeds begin to stir; at 4°C-5°C, the seeds can germinate and take root; when the soil temperature reaches 8°C-10°C, the needs of seed germination and emergence can be met. The optimum temperature for sunflower development is 31°C-37°C. The optimum daytime temperature for growth is 18°C-30°C, and the night temperature is 10°C-18°C. Throughout the entire growth process, sunflowers can grow normally as long as the temperature is not below 10°C. Within the suitable temperature range, the higher the temperature, the faster the development. If the temperature is on the low side in early spring, plant growth is slow, directly affecting flowering time. But when the temperature is above 30°C, the stems and leaves grow excessively, the stems become slender and break easily, and the flowering period is shortened. Therefore, when cultivating under protection, ventilate when the midday temperature is above 25°C, and keep warm and heat when the nighttime temperature is below 13°C.
Ornamental sunflowers are light-loving flowers, and their seedlings, leaves and flower discs all have strong phototropism. Sufficient sunshine at the seedling stage makes for robust seedlings; sufficient sunshine in the mid-growth period can promote stem and leaf growth and flower bud differentiation. For open-field cultivation of ornamental sunflowers, long light hours often lead to slightly earlier flowering; while cultivation in a greenhouse in winter, with short light hours, delays flowering.
If there is sufficient sunlight throughout the growth and development period, the stems and leaves grow robustly, the flower colors are vivid, and the ray florets are glossy; if it is continuously rainy or the plants grow for a long time in a semi-shaded environment, the stems are not upright, the leaves are soft, drooping and yellow-green, and the flower discs are small and irregular.
6. Pruning ornamental sunflowers:
Plant management: to make the terminal bud of the main stem develop robustly, side (axillary) buds can be removed. For plants with somewhat taller stems, in windy seasons, stakes and netting should be set up for support to prevent lodging. In field cultivation, bottom leaves should be removed promptly to improve ventilation and avoid disease outbreaks in hot seasons.
For cut-flower varieties, the terminal flower bud should be removed to favor side-branch growth, so that the flowers on the side branches are uniform in size. After this treatment, 7-10 cut flowers can be harvested per plant, with stems reaching 70-80cm and the whole plant height reaching 120-170cm. Some varieties produce side buds at every node, which need to be removed promptly so as not to divert nutrients and affect the growth of the main bud.
If used for flowerbed display, pinch once, and the branches can produce 4-5 flowers. For potted plants, a single flower is preferable. For tall-stemmed varieties sown in pots, 20 days after germination, spray the leaves with a 0.25%-0.4% daminozide solution to control plant height.
7. Flowering period management for ornamental sunflowers:
Sunflowers are cross-pollinated and can set seed through pollination by insects and bees. Artificial supplementary pollination during flowering can increase the seed-setting rate. Double-flowered varieties in particular do not set seed easily and require artificial pollination when flowering. The pollination time is from 9 to 11 a.m. each day, and generally pollination can be done 2-3 times.
Flowering period control: using pruning or staggered sowing can appropriately extend the flowering period.
The length of the growing period of ornamental sunflowers varies with variety, sowing date and cultivation conditions, and the sowing date can be determined according to the desired viewing time. Starting in March, sow once every 20 days, with the last sowing in early May; this appropriately extends the flowering period, and the plants grow relatively more vigorously with better flower quality.
Using pruning to extend the flowering period can make the supply period of ornamental sunflower cut flowers run from late June to early September. According to the plant's growth vigor, apply additional fertilizer, promptly remove overly dense branches, weak branches, bottom leaves and small buds, and retain 1 flower and 1 bud so that the flowers develop large and full.
If you want to extend the flowering period by 1 month, prune and pinch once at the end of May, leave 2-3 leaves and remove the top tip, remove the tiller buds at the base to promote side branches; supplement with fertilizer and water, and cultivate and loosen the soil 1-2 times; flowering can then occur in July-August.
If you want to extend the flowering period by 2 months, perform a second pinching in mid-June. The specific method is: pinch at 3-5cm above the new shoots that emerged after the first removal of the top tip, and remove the basal tiller buds, weak branches and overly dense lower leaves, retain the thick, strong branches, and apply liquid fertilizer once a week. Flowering can then occur in August-September.
8. Pest and disease control for ornamental sunflowers:
The incidence of pests and diseases in sunflowers is relatively low. The main diseases are powdery mildew, black spot, bacterial leaf spot, rust (prevalent in high-humidity periods) and stem rot. They can be prevented by sterilizing the substrate, watering reasonably, increasing air circulation and intermittently spraying protective fungicides. After infection, remove diseased leaves and residual plants and burn them in a centralized manner; in the early stage of the disease, spray with 50% thiophanate-methyl wettable powder at 500 times dilution or use an equal-amount Bordeaux mixture for control.
Pests harming sunflowers include aphids, plant bugs, red spider mites and scarab beetles, which can be controlled by spraying with 40% omethoate emulsifiable concentrate at 1000 times dilution or 73% propargite emulsifiable concentrate at 1500 times dilution.
V. Harvest time for ornamental sunflower cut flowers:
They can be harvested when the outer ray florets open. Vase life in water or preservative solution is 6-8 days in summer and up to 10-15 days in winter. Generally, during harvest and packaging, remove the leaves and keep 1 leaf at the top. Cut flowers can be stored at 2°C-5°C for about 1 week.
The side branches of ornamental sunflower cut flowers must reach more than 40cm in length. The flowering period begins in late June; select flower stems 60-70cm long to harvest, carry out pretreatment, then bundle 10 stems per bunch, wrap the flower heads in soft paper, pack and bring to market.
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