A Complete Guide to the Latest Rose Cultivation Methods

The rose is known as the king of flowers, also called “monthly red,” of the Rosaceae family. An evergreen or semi-evergreen low shrub, blooming in all four seasons, mostly red, or pink, occasionally white, it can be used as an ornamental plant and as a medicinal plant, also known as rose flower. Its natural flowering period is from May to November, with large, fragrant flowers, widely used in horticultural cultivation and cut flowers. The main types of roses include cut-flower roses, edible roses, climbing roses, and ground-cover roses.

Growth Habits

Highly adaptable, not tolerant of severe cold or high temperatures, drought-tolerant, not strict about soil requirements, but best in slightly acidic sandy loam rich in organic matter with good drainage. The potting soil should be loose, the pot diameter appropriate, moisture moderate, fertilizer applied lightly and often, flowers picked and branches pruned, pests and diseases controlled, and the pot changed every year. It likes sunlight, but too much direct strong light is unfavorable to flower bud development, and petals tend to scorch. It likes warmth; generally a temperature of 22-25°C is the most suitable for flower growth, and high summer temperatures are unfavorable for flowering.

It needs sufficient sunshine, air circulation, good drainage, and a wind-sheltered environment, with appropriate shading in midsummer. For most varieties the optimum temperature is 15-26°C during the day and 10-15°C at night. It is fairly cold-tolerant; when the winter temperature drops below 5°C it enters dormancy. If summer high temperatures persist above 30°C, most varieties flower less, quality declines, and they enter a semi-dormant state.

Generally varieties can withstand low temperatures of -15°C. It requires slightly acidic soil rich in organic matter, fertile and loose, but its range of soil adaptability is fairly wide. Relative air humidity is best at 75%-80%, though slightly drier or slightly moister is also acceptable. It has the characteristic of continuous flowering. It needs air circulation and no pollution; if ventilation is poor, powdery mildew is likely to occur, and harmful gases in the air, such as sulfur dioxide, chlorine, and fluorides, are all toxic to roses.

Propagation Techniques

Mostly cutting propagation is used, and division and layering propagation are also possible. Cuttings can be taken in all four seasons, but hard-wood cuttings in winter or autumn are preferable; for green-wood cuttings in summer, attention must be paid to water management and temperature control. Otherwise rooting is difficult. Winter cuttings are generally done in a greenhouse or plastic tunnel; if cutting in the open field, measures to increase moisture retention must be taken. Propagation by sowing is used for sexual hybrid breeding. For a few rare varieties that are difficult to root, grafting propagation is used, and the rootstock is best wild rose. For example, the yellow series varieties.

Management Methods

Rose transplanting is carried out between November and March of the following year, and pruning can be done at the same time as transplanting. First cut away dense branches and dead branches, then cut away old and weak branches, leaving 2-3 outward-growing buds so as to spread in all directions; appropriately shorten particularly strong branches to strengthen the growth of weak branches. In summer, when new branches grow too densely, thin them out. After each batch of flowers fades, promptly cut off the upper part of the branch connected to the spent flower so that it does not set seed and consume nutrients, keeping the plump middle and lower parts of the branch to promote early new growth and reblooming. Roses like a heavy application of base fertilizer before flowering and a top dressing of quick-acting nitrogen fertilizer after flowering to strengthen the plants and force flowers. Roses have strict water requirements and must not be too wet or too dry; too dry and they wither, too wet and the roots are damaged and leaves drop.

1. Flowering Period Control

The rose is also called “monthly red,” with a natural flowering period from May to November, blooming continuously. However, controlling the flowering period of roses during the Olympics is still very important, especially for potted roses and cut-flower roses, the flowering period must be well controlled to fully accomplish the tasks of temporary flower displays at various venues and stadiums and the supply of fresh cut flowers during the Olympics.

In actual work, specific situations should be analyzed specifically. For field-planted roses, according to their geographical location, while ensuring continuous flowering, let them bloom more and bloom well from August 8 to 24. The following methods are for reference: around June 20, prune all spent flowers and part of the already fully bloomed flower branches of field-planted roses at a ratio of 50%, cutting to the round bud position at the mature middle part of the flower branch; their flowering ornamental period is about August 1 to 15; around June 30, prune all spent flowers and all post-bloom flower branches by the above method, and their flowering ornamental period is about August 10 to 25; after June 30, prune spent flowers at any time to let them bloom naturally. For potted roses and cut-flower roses, calculate the date the flowers are needed well, and about 45 days before that date, carry out a comprehensive pruning of the branches.

Fertilizer and Water Management: In the above pruning situations, scientific fertilizer and water management should be carried out in accordance with the plant's growth vigor. After the plant is pruned, when the new generation of buds does not sprout, spray 0.2% urea on the leaves once every 5 or 6 days, which can promote new bud sprouting; if the plant grows fast and new branches grow rapidly, exceeding the planned range, controlling the water supply can slow growth. During water control, take the point at which the branches and leaves wilt, then water promptly and recover within 1 hour as the critical limit. Water is the carrier of various enzymes in the plant body; if the water supply is insufficient, enzyme activity decreases, metabolism slows down, and thus plant growth slows down. If new branches bud later than planned, at this time spray 0.2% monopotassium phosphate on the leaves once every 5 or 6 days, and the flower buds will grow rapidly. The rose flowering period consumes a large amount of water and internal nutrients, so the water supply must be sufficient.

2. Flowering Conditions

① Sunshine must be long. The place where roses are planted must be both ventilated and able to receive more than half a day of sunlight. This is the primary condition for it to bloom profusely like brocade. If placed in a half-shade half-sun location or a shaded place with insufficient light, it can bloom at most only in spring and autumn in a year. Therefore, families whose living conditions cannot meet the light requirements had best not grow roses and instead grow shade-loving flowers and plants.

② Prune often. Although the sunshine conditions are good, if not pruned for a long time, roses will not grow well either. The pruning method is: after December each year when the rose leaves fall, carry out one pruning, leaving branches about 15 cm high, with the pruning point about 1 cm above an outward-extending leaf bud, and at the same time remove side branches, diseased branches, and concentric branches. After May, each time a round of flowers finishes, cut away 2/3 or 1/2 of the branch that has flowered, so there will be more opportunities for regenerated flower buds. If you want the flowers to bloom larger, you can also remove part of them when there are many flower buds, which both concentrates nutrients and achieves the purpose of extending the flowering period and opening in batches.

③ Apply fertilizer frequently and promptly. Generally, newly planted or transplanted potted roses can be cultivated with humus-rich, loose loess soil, best mixed with 1/4 rice husk ash or a little broad bean shell, bean cake, or chicken and pigeon manure, so that the rose can continuously absorb various nutrients such as nitrogen, phosphorus, and potassium from the soil. If an old potted rose needs repotting, the base fertilizer can also be applied by the above method; if not repotting, you can scrape open 2-3 cm of the soil surface and bank in some fresh fish innards or chicken and pigeon manure, bean cake crumbs, etc. as base fertilizer. This is best done in January to February when the rose is dormant. In this way, the fertilizer will gradually ferment into fertilizer liquid and seep into the roots with rain or watering for better results. After May is the peak growth season for roses; every 10 days, apply a top dressing once. You can use fully fermented fishy juice or vegetable leaf juice mixed in a ratio of 3 parts fertilizer to 7 parts water and apply it, and stop fertilizing in November. If you can do as required above, you can have fresh roses to meet you every month. Roses are by nature averse to heat; they grow best at 20-25°C; above 30°C growth becomes difficult. If you handle the fertilization step well, you can overcome its weakness of fearing high summer temperatures.

④ Repotting. Roses do not need to be repotted or have their pots turned every year; if it is moving from a small pot to a large pot, it can be done in all four seasons.