What are the cultivation methods and precautions for gardenia?

The gardenia has a beautiful and highly attractive appearance, releases a fresh fragrance, and has excellent ornamental value. A well-cultivated gardenia has emerald-green leaves and jade-white flowers. Do you know what the cultivation methods and precautions for gardenia are? And what are the reasons why gardenias fail to bloom? Let's take a look together below!

Propagation methods for gardenia

1. Cutting propagation: In May to June, select semi-lignified, well-developed young shoots, cut them into 10 to 15 cm lengths, soak the base in 1000 mg/kg naphthaleneacetic acid for 3 to 5 seconds, and insert them into acidic soil with strong water and nutrient retention. Generally, a mix of 3 parts leaf mold or mountain soil and 1 part sawdust, peat, or river sand can be used. After insertion, roots can form in about 1 month, and transplanting can be done after 50 days. In southern China, water propagation is often used in summer, carried out from April to July. The prepared 10 to 15 cm long cuttings, with 2 to 3 leaves retained at the top, are inserted into a woven basket lid or a perforated plastic board, which is floated on the water surface, with the upper part of the cuttings exposed above the water. After insertion, place in semi-shade, maintain the water temperature at 16 to 18°C, and new roots can grow in 20 days. When the temperature is high, change the water frequently, once a day, and do not let the water deteriorate. When the roots grow to 2 to 3 cm, they can be transplanted.

2. Layering propagation: Mostly carried out from May to June. Select 1 to 2-year-old robust branches, 25 to 30 cm long, press them into the soil 3 to 5 cm deep. Roots can form in about 1 month, and they can be cut from the parent plant after 2 months. Air layering can also be used, that is, on a mature gardenia, select 2 to 3-year-old robust branches, girdle the bark 1 to 2 cm, then wrap with moist peat, tie tightly with a plastic bag on the outside, keep the soil moist, and new roots can grow in about 40 days. Cut from the parent plant after 2 to 3 months.

3. Division propagation: In May, if there are 2 to 3 branches growing together at the base of the root, cut them apart from the root with a knife. Each division should have fine roots. After applying plant ash to the wound, plant them separately.

Cultivation methods for gardenia

1. Potting soil selection: Gardenia is an indicator flower that prefers acidic soil, with a suitable pH value of 5 to 6. Therefore, a slightly acidic soil environment is the key to determining whether gardenia grows well. If the soil acidity is unsuitable, future management will achieve twice the result with half the effort. The culture soil should be a mix of 7 parts slightly acidic sandy red soil and 3 parts leaf mold. It is advisable to control the soil pH between 4.0-6.5. For cultivation soil, you can choose leaf mold, peat soil, or composted sawdust plus half garden soil. Avoid using old wall soil and coal cinder. Using commercially available clivia soil is more convenient and practical.

2. Scientific watering: Gardenia prefers moist soil and relatively high air humidity. During the growing period from April to September, keep the potting soil moist. During the growing period, appropriately increase watering. Usually, water when the potting soil turns white, and water thoroughly at one time. In hot summer, spray the leaf surface 2 to 3 times a day to increase air humidity and help the plant cool down. However, after flower buds appear, watering should not be too much to avoid bud drop. In winter, it is better to keep watering on the dry side to prevent root rot from excessive water. Water when the surface of the potting soil looks dry, and in the evening, you can use a spray bottle to sprinkle water on the leaf surface. If it dries out completely and wilts, it will be detrimental to growth. For plants that grow too vigorously with longer internodes, do not water at night; water in the morning after the sun comes out. In northern regions with alkaline water, tap water should be left to stand for two days before use. Every three to five days, water thoroughly once with a water solution containing 0.5 g citric acid and 1 g ferrous sulfate per liter, which can make the leaves glossy and emerald green.

3. Reasonable fertilisation: Gardenia's demand for fertiliser: Gardenia is a fertiliser-loving plant. 3% decomposed cake fertiliser can be added to the culture soil as a base fertiliser. During the growing season, water once a week with alum fertiliser water made by composting cake fertiliser and ferrous sulfate, or use 0.1% humic acid full-nutrient organic liquid fertiliser. During the bud stage, water once to twice with 0.1% potassium dihydrogen phosphate aqueous solution, which can make the flowers larger and the fragrance richer. Stop fertilising during the hot summer period when the temperature is above 35°C and in autumn when it is below 15°C. After entering the peak growing season in April, apply top dressing once every half month (when fertilising, it is best to dilute with more water to prevent burning the flowers). This can not only meet the gardenia's demand for fertiliser but also keep the soil environment in a relatively balanced slightly acidic state, prevent the occurrence of chlorosis, and at the same time avoid the damage to gardenia from sudden supplementation of ferrous sulfate and local over-acidity.

4. More sunlight: Gardenia likes light. It can also grow in semi-shade for a long time, but the flowering branches will be longer and the flowers fewer. Except for the need for shading from strong midday light from July to August and during the winter dormant period, it generally needs to be placed in sunlight for care to achieve abundant flowers and lush leaves.

5. Good winter dormancy: Gardenia can overwinter outdoors in the Qinling area of China, but potted gardenias will suffer root damage after severe winter, and recovery in spring will be slow. Overwintering indoors with heating, although not affected by freezing damage, has insufficient light, causing weak growth, and most young buds formed in autumn will drop, resulting in late flowering the next year. A better method is to place the potted flower in a cold room at around 5°C to make it dormant, or wrap the flower pot well with foam plastic and other insulation materials to protect the root system, and place it in a windproof and sunny place to overwinter. In this way, recovery in spring is fast and flowering is early.

6. Timely repotting and soil changing: Small seedlings use small pots, and gradually move to larger pots. When the crown width is 2 to 3 times the diameter of the pot mouth, it is time to repot. Repotting can be done at any time during the growing season. After turning out the pot, plant the root ball with soil into the new pot. It is advisable for the new pot mouth to be about 5 cm larger than the original pot. For home potted plants, when the pot reaches about 28 cm, generally no more repotting is done, only the potting soil is changed. It is better to change the soil in March in spring. After turning out the pot, cut off some old roots, shake off half of the old soil, plant into the pot with new soil, water thoroughly, place in a warm semi-shade place, and place in sunlight for care when new buds sprout.

7. Proper pruning: For large-flowered gardenia seedlings, pinch off the tip at 20 cm on the main trunk, keep 3 to 4 branches, and when the branches have 2 pairs of leaves, pinch off the tips again to promote branching, after which they can be allowed to grow freely. Small-leaved gardenia does not need tip pinching. After flowering each year, lightly prune, cutting off inner branches and diseased or weak branches, and shortening individual leggy branches. For large-flowered gardenia, when the crown width becomes too large after 4 to 5 years, severe pruning can be done after flowering. Generally, the upper branches are shortened to 2 pairs of leaves. After budding, remove buds growing inward and buds on the lower part of the main trunk, and the plant shape will become more compact and beautiful. Remember that gardenia should not be shortened at the branch tips in spring, otherwise it will not bloom that year.

Precautions for gardenia cultivation

1. Gardenia likes fertiliser but fears concentrated fertiliser. Generally, before buds appear, apply 2 times of cake fertiliser water containing more phosphorus and potassium. Stop fertilising after buds appear. If too much fertiliser is applied, it is easy to burn the roots and cause bud drop. During the growing period, apply decomposed cake fertiliser water or manure water once every half month, and add 1% to 2% ferrous sulfate to prevent soil alkalinisation.

2. Gardenia likes semi-shade and fears direct strong light. It requires a shade density of about 50%. If exposed to the sun, the leaves will turn yellow, then white, and finally fall off. Therefore, in summer, it must be placed in a shaded place or a place with scattered light for care. Let it receive light in the morning and evening to avoid yellowing of the leaves.