Detailed Explanation of Key Techniques for Propagating China Aster by Seed
China aster is a very important horticultural variety both in China and abroad. Internationally, dwarf varieties are now used for pot cultivation and ornamental display in flower beds. China aster has a long history of cultivation and is one of the most important potted flowers. Artificial propagation of China aster can be done by sowing seeds.
China Aster
China aster is commonly propagated by seed. The sowing time depends on the variety and intended use. Taking the pot variety Asteroid Series as an example: seeds can be sown from November to April of the following year, and flowering can occur from April to August. Each gram of China aster seed contains 420 to 430 seeds. The optimum germination temperature is 18 to 21°C, and germination occurs 7 to 21 days after sowing. Seedlings grow rapidly, so thinning should be done in a timely manner. Use fully decomposed high-quality organic fertilizer as a base fertilizer, and chemical fertilizers can be used as top dressing. Generally, spring sowing is most common, but summer and autumn sowing are also possible. Flowers can bloom 2 to 3 months after sowing.
Sowing can be done in batches as needed to control the flowering period. Dwarf types: sow in a greenhouse in February to March or in a cold frame in March, and they will bloom in May to June; sow in the open field in April to May and they will bloom in July to August; sow in early to mid-July and they can bloom for National Day (October 1); sow in early to mid-August, and the seedlings overwinter in a cold frame and bloom for May Day the following year. Medium varieties: sow in May to June and they bloom in August to September; sow in August and they need to overwinter in a cold frame, blooming in May to June the following year. Tall varieties: can be sown in both spring and summer, all blooming in autumn, but early summer sowing is preferable. With early sowing, the plants are tall and the leaves are old at flowering time, with the lower leaves turning yellow and withered.
Control Methods for Damping-off of China Aster
Key Identification Points:In the middle to late seedling stage, the plants are affected, producing oval dark brown lesions at the stem base that are sunken. As the disease progresses, the lesions gradually expand and can encircle the stem. The diseased area constricts, and the affected plant gradually dies starting from the lower leaves, eventually the whole plant dies. When humidity is high, mycelium grows on the lesions; the mycelium is brown and spiderweb-like, and sometimes brown irregular sclerotia can be seen. When seed propagation is infected, it can cause seed rot and failure of seedling emergence.
Occurrence Characteristics:The pathogen is Rhizoctonia solani. Under suitable temperature and humidity conditions, the mycelium invades the host and spreads with rainwater, irrigation water, and agricultural operations. It occurs frequently when seedlings are too dense, leggy, or when seedbed temperature management is unreasonable.
Control Methods:
(1) Choose a disease-free seedbed with good drainage.
(2) Disinfect the seedling bed soil. Formaldehyde fumigation can be used: 20 days before sowing, spray 40 mL of formaldehyde mixed with 2 to 4 L of water per square meter, immediately seal with plastic film, remove the film after 1 week and loosen the soil, and sow after 2 weekssowing. Alternatively, mix 50% carbendazim wettable powder or 70% thiophanate-methyl wettable powder with soil at a 1:200 ratio of chemical to soil. For home flower-growing, pot soil can be sterilized by high temperature.
(3) When scattered cases occur, spray with 75% chlorothalonil wettable powder at 800 times dilution, 64% oxadixyl-mancozeb wettable powder at 500 times dilution, 50% carbendazim wettable powder at 800 times dilution, or 5% jinggangmycin aqueous solution at 100 times dilution.
August Home Flower Growing Tips
Flowers suitable for courtyard display in August: The temperature is high, light is intense, and humidity is low. It is the second hottest period of the year after July in terms of high temperature and dry heat, with the monthly average temperature in most parts of the country ranging between 24°C and 28°C.
Potted ornamental plants suitable for courtyard display are those that prefer light or tolerate high temperatures.
Among woody flowering plants, the main ones are: Norfolk Island pine, Japanese black pine, Japanese five-needle pine, five-needle pine, golden larch, Japanese golden larch, lacebark pine, Japanese fir, Armand pine, Buddhist pine, Chinese juniper, sago palm, Canary Island date palm, Chinese fringetree, Lanyu cinnamon (Cinnamomum kotoense), fragrant olive (Aglaia odorata), pomegranate, rubber tree, variegated fig, Chinese hibiscus, lantana, coral tree (Erythrina), Dutch iron plant, croton, dragon tree, lady palm, money tree, schefflera, frangipani, four-season osmanthus, oleander, Washington palm, windmill palm, bottle palm, leatherleaf mahonia, Japanese fatsia, etc. Chinese rose, etc.
Herbaceous flowers include: garden balsam, large-flowered canna, variegated shell ginger, scarlet sage, dahlia, China aster, bamboo begonia, snapdragon, marigold, peacock chrysanthemum (peacock chrysanthemum), phlox, five-color pepper, California poppy, cockscomb, pot marigold, spider lily, periwinkle, globe amaranth, sulfur cosmos, four o'clock flower, zinnia, etc. In addition, there are also cast iron plant, Guangdong evergreen, Philodendron bipinnatifidum, Monstera deliciosa, pothos, silver queen aglaonema, etc.
Propagation of Courtyard Flowers
1. Sowing In August, woody flowering plants that can be sown include: tree peony, elm-leaved spirea, red-flowered camellia, summer sweet shrub, American summer sweet shrub, Buddhist pine, etc. They can be sown immediately after collection, or the seeds can be stored in wet sand until they crack and show white, then sown in the ground. Canary Island date palm can be sand-stored for germination and then sown in bags. Ornamental pomegranates are harvested after they mature and crack; rub and wash off the fleshy layer outside the seeds, store in sand until germination, then sow. Herbaceous flowers that can be sown include: baby's breath, fan columbine, dwarf petunia, snapdragon, coneflower, oxalis species, yarrow, nasturtium, pyrethrum, etc. Greenhouse flowers that can be sown include: calceolaria, cyclamen, cineraria, wax begonia, fairy primrose, coleus, pot marigold, etc.
2. Cuttings Use a mixed medium of alkaline-leached rice husk ash and moist fine sand at a 2:1 ratio for moisture-retaining bed cuttings or pot cuttings. The following flowering plants can be propagated: firethorn, mahonia species, wintersweet, banana shrub, bougainvillea, coral tree, fragrant olive (Aglaia odorata), spotted laurel, Chinese snowball viburnum, snowball viburnum, Chinese hibiscus, jasmine, chloranthus, rubber tree, galwood, Buddhist pine, schefflera species, ti plant, hydrangea, purple magnolia, etc. Using yellow subsoil or sandy loam as the medium, the following can be cuttings-propagated: boxwood species, pomegranate, rose of Sharon, French holly, golden-edged privet, red-leaf barberry, nandina, fig, oleander, crape myrtle, Japanese snowflower, spiraea, bridal wreath spiraea, gardenia, etc. In addition, herbaceous flowers such as scarlet sage, globe amaranth, marigold, and sulfur cosmos can also be cuttings-propagated this month.
3. Grafting In August, the following flowering plants can be grafted: In northern regions, use fringe tree as rootstock for approach grafting of osmanthus; use purple magnolia or white magnolia as rootstock for bud grafting of saucer magnolia; use potted purple magnolia as rootstock for approach grafting of white orchid; use current-year seedling of wild peach as rootstock for bud grafting of plum blossom, ornamental peach, longevity peach, purple-leaf peach, double-flowered dwarf cherry plum, elm-leaved spirea, etc.; use cherry seedling as rootstock for bud grafting of Japanese cherry; use wild rose, pink cluster rose, etc. as rootstock for bud grafting of improved rose varieties; use Manchurian crabapple, Chinese pearleaf crabapple, Hupeh crabapple, etc. seedlings as rootstock for bud grafting of Midget crabapple and Hall crabapple; use green maple as rootstock for crown replacement grafting of red maple and feather maple; use single-trunk rubber tree as rootstock for stem grafting of variegated weeping fig; use single-petal camellia as rootstock for stem grafting of improved camellia varieties; use seedling wintersweet as rootstock for stem grafting and approach grafting of improved wintersweet varieties. In addition, cleft grafting can be used to propagate large-flowered wisteria.
4. Layering In August, ornamental plants that can be propagated by layering include: Japanese honeysuckle, Chinese trumpet creeper, banksia rose, climbing rose, weigela, hydrangea, Chinese snowball viburnum, snowball viburnum, oleander, gardenia, broom, winter jasmine, forsythia, Japanese quince, Hall crabapple, Midget crabapple, osmanthus species, purple magnolia, jasmine, chloranthus, banana shrub, Chinese hibiscus, Buddhist pine, coral tree, rubber tree (air layering), fragrant olive (Aglaia odorata) (air layering), red maple (air layering), etc.
5. Division In August, ornamental plant species that can be propagated by division include: lily turf, hosta, purple hosta, little angel, multi-head green king, bromeliads, Solomon's seal, cast iron plant, umbrella plant, water buttonbush, red (green) gem, iris, blackberry lily, purple triangular oxalis, Guangdong evergreen, Dutch aster, fine-leaf acorus, sword fern, silver queen aglaonema, arrowroot species, syngonium, Haworthia, etc. In addition, spider lily, calla lily, freesia, etc. can also have their small bulbs divided and replanted this month. Management of Courtyard Field-Grown Flowers
1. Transplanting In August, for some flowering shrubs transplanted with large soil balls and supplemented by heavy pruning, shading, watering, and misting management should be strengthened after transplanting to achieve a relatively high survival rate. Examples include: golden-leaf privet, red-leaf barberry, golden-edged thuja, golden-hearted (golden-edged) boxwood, hypericum, mahonia, Japanese fatsia, Chinese rose, azalea, gardenia, Buddhist pine, banana shrub, dragon juniper ball, Chinese juniper ball, boxwood ball, pomegranate, rose of Sharon, spotted laurel, French holly, etc. In the courtyard, herbaceous flowers can also be transplanted and established, such as scarlet sage, globe amaranth, marigold, cockscomb, peacock marigold (peacock marigold), snapdragon, etc., which can be expected to bloom in September and October.
2. Pruning In August, for hedges in the courtyard such as boxwood, small-leaf privet, privet, golden-leaf privet, French holly, and photinia, pruning should continue. For field-grown ball-shaped plants such as photinia, dragon juniper, Chinese juniper, bayberry, firethorn, pittosporum, holly, and evergreen, pruning must also be done again. For field-grown flowering plants that bloom continuously for a long time, such as Chinese rose, pomegranate, rose of Sharon, crape myrtle, Chinese hibiscus, bougainvillea, and lantana, spent flowers should be removed in a timely manner, and the branch tips should be moderately shortened. For field-grown herbaceous flowers such as scarlet sage, globe amaranth, early chrysanthemum, peacock chrysanthemum (peacock chrysanthemum), and marigold, pinching and tipping should be carried out.
3. Watering In August, for flowering shrubs transplanted in spring and established herbaceous flowers, watering and misting management should be strengthened. For plants with straw ropes tied around the trunks, the straw ropes should be sprayed wet to ensure that the plants do not show wilting of new shoots and young leaves. Mist frequently and water cautiously to ensure no water accumulation at the roots.
4. Fertilizing In August, for field-grown red-leaf photinia, golden-edged (golden-hearted) boxwood, red-leaf barberry, golden-leaf privet, purple-leaf sand cherry, croton, red mulberry, spotted laurel, variegated shell ginger, etc., in order to maintain bright leaf color for a long time, quick-acting fertilizers with a relatively balanced ratio of nitrogen, phosphorus, and potassium should be applied as top dressing. For species that continue to bloom, such as Chinese rose, daily fragrant osmanthus, four-season osmanthus, flowering pomegranate, rose of Sharon, crape myrtle, bougainvillea, dahlia, and lantana, as well as species about to bloom such as osmanthus, chrysanthemum, cotton rose, and autumn anemone, appropriate amounts of quick-acting phosphorus and potassium fertilizer should be applied promptly. For camellia, sasanqua, plum blossom, and wintersweet, which are in the stage of flower bud differentiation, a small amount of monopotassium phosphate solution can be applied by foliar top dressing.
5. Pest and Disease Control In August, for scale insects occurring on plants such as deodar cedar, privet, pittosporum, osmanthus, crape myrtle, photinia, and camellia, spray 40% Supracide at 1500 times dilution promptly for control. For chrysanthemum beetles and aphids occurring on field-grown chrysanthemums, spray 90% trichlorfon crystal at 1000 times dilution for killing. For larvae such as rose sawfly and cotton leafworm that chew rose leaves, spray 10% fenvalerate at 1000 times dilution promptly for control.
6. Seed Collection In August, woody flowering plant species from which seeds can be collected include: tree peony, elm-leaved spirea, red-flowered camellia, Buddhist pine, summer sweet shrub, etc. Herbaceous flowers from which seeds can be collected include: Chinese peony, moss rose, four o'clock flower, phlox, California poppy, snow-in-summer, etc. Management of Courtyard Potted Flowers
1. Watering In August, watering should be done between 9 and 10 a.m. and after 4 p.m., keeping the water temperature basically consistent with the soil temperature and air temperature. For ornamental plant species that prefer acidic conditions, 0.1% ferrous sulfate can be added to the irrigation water. It is worth noting that for ornamental plants with dense fine hairs on the leaf surface, such as calceolaria, gloxinia, iron cross begonia, and hairy-leaf begonia, water droplets on the leaf surface do not evaporate easily and can easily cause leaf rot, so only a small amount of misting is permissible; the leaf rosette flower buds of Gerbera (African daisy) and the center of the leaf rosette of clivia should not be drenched with water either, as dirty water flowing into the leaf rosette can cause heart rot; for bromeliads, water less and mist more, and inject water into the leaf cups to meet their needs. This month, while watering and misting potted plants, be sure to loosen the soil, once every 10 days, otherwise repeated watering will cause the potting soil to become compacted. For flower species in dormant or semi-dormant states, control watering and misting, maintaining the potting soil at a slightly moist level, and create a relatively cool and moist environment by misting the small environment around the flower pots.