Apply large amount of water and fertilizer at the germination stage in early spring to make it grow vigorously. Early-flowering varieties began flower bud differentiation around April 12, and began flowering around May 27. Fertilizer should be applied twice during the whole growth period of hibiscus. For the first time, before the leaf buds began to sprout in spring, urea, phosphate fertilizer and human excrement and urine were applied to dig a hole outside the drip boundary of the crown, and 1-3 kilograms of fertilizer was applied to each plant. The second time, at the beginning of flowering, urea was applied, and fertilizer was sprinkled on the root of the crown, then water was poured, and .5 kg fertilizer was sprinkled on each plant. It takes 4-45 days from flower bud differentiation to flowering. Water more in hot summer, keep moist, and reduce moisture in autumn.

. After pruning the hoary head frost in December, or before sprouting at the end of winter and spring, all the big branches can be cut short or sawed off, leaving only 1-1.6m-long branches, leaving 15-2 boxes of short branches on the piles for re-pruning, combining spring fertilization with bud wiping and pruning, leaving only 4-5 new buds on each branch pile, and erasing all the others. In midsummer, although the buds are smeared in winter and spring, there are still many redundant branches, which should be pruned in time. Otherwise, the ventilation and ventilation will be affected. The branches of pests and diseases should be scraped with a knife, brushed or pruned and burned. Plastic pruning in winter has an important influence on the growth and tree shape of paulownia. If it is not cut in winter in time and reasonably, the tree shape will be chaotic, with long main branches, few leaves or low clusters, which will greatly reduce its ornamental value and shading effect. Timely and reasonable pruning can make the tree majestic, straight and beautiful, the branches are dense and well-proportioned, the leaves are thick and green, and the natural immunity of the tree is enhanced in a short time.

The shaping and pruning of paulownia trees in winter can be carried out before the leaves of paulownia trees fall off in autumn and winter, the soil freezes, and the trees are dormant until the sap flows in the following spring. For newly planted young trees, when the stem is as high as 2.5 to 3 meters, it is called "fixed stem" Pruning can be based on the overall observation of the whole tree body and the decision of the future cultivation direction. First, cut the upright branches and drooping branches, then cut the branches of diseases and insect pests, cross branches, weak branches, inward branches and branches that affect traffic facilities, and finally leave 3 to 4 strong main branches. The main branches should be conducive to future plastic surgery, grow strong and have a moderate opening angle. After selecting the main branch, cut it short 3-4 cm near the base, the cut should be smooth and not damage the bark, and the cut should be coated with a protective agent to avoid pests and diseases and water transpiration. Smoothing the wound can also promote the formation of callus, which is beneficial to wound healing and prevent bacterial infection. The wound protection agent can be wax, white paint, tung oil or paint.

young trees should be cut off once every 3 to 4 years in winter. Generally, the three or four main branches retained for the first time can be basically unchanged, and then one or two strong branchlets can be retained on each main branch, and the length can be 2 to 3 cm when it is cut short. The lateral branches on the branchlets can be retained according to the specific conditions. For example, when the communication line near the tree is not high, only 3 to 4 short main branches left during the first drying can be retained, which can reduce the height of the whole tree and increase the light transmittance of the branches, without affecting its growth and maintaining the tree shape well.

for the formed paulownia, it should also be fully pruned every winter. Pay attention to cultivating the advantages of main branches, and cut off the branches of diseases and pests, erect branches, overlapping branches, densely clustered branches and side branches. Retract the main branches that are too long, stimulate the branches and leaves at the base of the main and side branches to prevent baldness and ensure a thick leaf curtain layer.

paulownia has strong germination and is very resistant to pruning. If pruning is reasonable, it can keep the beautiful shape of the tree. If pruning is unreasonable, it can be made up in time in the next pruning to achieve its due tree-like effect. Fertilize according to the characteristics of fertilizer demand of seedlings in different growth periods. Seedling growth is generally divided into four stages: seedling stage, seedling stage, fast-growing stage and hardening stage. The nutrition source of seedlings at seedling stage mainly depends on the nutrients stored in seeds. Seedlings at seedling stage are sensitive to nitrogen and phosphorus, and nitrogen fertilizer is mainly applied to promote seedling protection and root growth. The fast-growing period is the most vigorous period of seedling growth, which requires the most fertilizer and water. The amount and frequency of nitrogen fertilizer can be increased, and phosphorus and potassium fertilizer can be applied in proportion to promote nitrogen absorption and seedling growth. In the hardening period when the aboveground and underground parts of seedlings are gradually lignified, it is necessary to prevent overgrowth, stop applying fertilizer and improve the resistance of seedlings.