Osmanthus Grafting Methods: Rootstock and Scion Selection and Key Post-Grafting Management Points

  September is truly the season of osmanthus fragrance, and among ancient Chinese poems praising flowers, the number of works celebrating osmanthus is quite considerable. "Not a plant of the mortal world, transplanted from the moon. A single breath of fragrance from the Guanghan Palace, blown until it blooms across the mountains" - this is about the fragrance of osmanthus. Before you even get close to the osmanthus, you can already smell a refreshing fragrance from afar. Back to the main topic - today the editor will talk about how to graft osmanthus.

  Osmanthus grafting is one of the main methods of osmanthus propagation. Using grafting can preserve the genetic characteristics of the mother tree and promote rapid growth of osmanthus, but the downside is that grafting has relatively high technical requirements. The technical requirements for osmanthus grafting are as follows:

  1. Rootstock selection

  In the south, grafting osmanthus mostly uses privet (Ligustrum) and ash (Fraxinus) as rootstock, while in the north, fringetree (Chionanthus) is mostly used as rootstock due to its strong cold resistance. When selecting rootstock for osmanthus grafting, choose a relatively large tree as rootstock, so that after grafting it grows fast, takes shape early, and has a short time to flowering. Of course, rootstocks of different thicknesses are suitable for different grafting methods. For example, a thin rootstock of 1 cm is suitable for tongue grafting, cut grafting, chip budding, and approach grafting, while thick rootstock is suitable for cleft grafting and bark grafting.

  2. Scion selection

  Select excellent individual plants that are disease-free, robust, true to variety, and heavy-flowering as mother plants. Collect well-developed one- to two-year-old branches from the outer canopy as scions for cut grafting and cleft grafting. One-year-old branches can be used as scions for bud grafting, while approach grafting should use 3-5 year old branch groups (clusters).

  3. Suitable grafting time

  In the south, the suitable time for spring grafting of osmanthus is generally March to May, and in autumn it is done in October.

  4. Grafting methods

  The grafting techniques for osmanthus are not very different from those for other plants. Scions should be collected and grafted immediately to avoid water loss. Regardless of which grafting method is used, the cambium layers of the scion and rootstock must be aligned. After grafting, wrap the joint tightly with plastic tape so that the tissues can make close contact, and also to prevent water loss.

  5. Post-grafting management

  For bud grafting, after the scion sprouts, cut off the upper part of the rootstock at a point 1 cm or more above the graft union; for approach grafting, after the graft union heals 2-3 months after grafting, cut through 1/2 of the scion below the girdling point, and after about one month completely cut the connection between the scion and the mother plant. New shoots sprouting from the rootstock should be removed promptly. Only after the graft has survived and grown new leaves can the binding material be removed. In the later stage, management measures such as wind protection and pest and disease control should be carried out well.

Key Points for Potted Osmanthus Care and Osmanthus Grafting Methods

When decorating the home, many people choose to place a few pots of osmanthus, which have beautiful plant shapes and pleasant fragrance. So, how do you care for potted osmanthus? How do you graft osmanthus? Below, we introduce the key points for potted osmanthus care and osmanthus grafting methods.

Key points for potted osmanthus care

1. Watering: For potted osmanthus, follow the principle of not watering when the soil is dry, and watering thoroughly when you do water. However, spray the leaves with clean water once a day, evenly moistening all branches and leaves, until water droplets begin to drip down, to keep the leaves moist and to wash off dust adhering to the leaves. After Qingming Festival, move the osmanthus outdoors and water thoroughly once. In summer, water in the morning and evening; in winter, water around noon, so that the water temperature is close to the soil temperature and avoids sudden cold or heat. Be careful not to let water accumulate. In winter, keeping the potting soil moist is sufficient.

2. Fertilizing: Osmanthus is mainly grown for its flowers, so it should be supplied with sufficient fertilizer. When new shoots are growing, apply nitrogen fertilizer 1-2 times to promote branch and leaf growth; before flower bud differentiation and flowering, mainly apply phosphorus fertilizer. In spring, after moving the osmanthus outdoors, begin watering with diluted decomposed soybean cake, sesame paste, or fish waste water, once every half month, and once a week from the end of May until before flowering, gradually increasing the fertilizer concentration. In July-August, apply a 0.5% potassium dihydrogen phosphate solution once every half month. After flowering, apply a light fertilizer solution once to avoid triggering autumn shoots. In winter, apply more organic fertilizer and phosphorus-potassium fertilizer. Generally, every 15-20 days apply to the roots 25-30 grams of decomposed and deodorized cake fertilizer and 10-15 grams of potassium dihydrogen phosphate, diluted with 2-3 jin of clean water, and spray the leaves every 10-15 days with a mixed solution of 1000x nucleotide and 600x high-efficiency biological phosphorus-potassium fertilizer, evenly moistening all branches and leaves until dripping begins. Before fertilizing, the potting soil should be slightly dry, and it is best to loosen the soil first to facilitate fertilizer absorption. Water once on the day after fertilizing. If using compost or barnyard manure, it must be completely decomposed before use (the sign is that the fertilizer liquid turns black). If using the chemical fertilizer superphosphate, its concentration must not exceed 2%, and urea concentration should be 0.5-1.0%.

3. Repotting: Potted osmanthus should be repotted and have its soil changed once every 2-3 years. Cut off part of the old roots and dead roots, and use a bamboo stick to remove part of the old soil. Before potting, place a layer of river sand or vermiculite at the bottom of the pot to facilitate aeration and drainage, and place decomposed cake fertilizer at the bottom as base fertilizer. Be sure to firm the soil when filling, which can promote lush flowers and leaves in osmanthus. The soil mix for potted osmanthus is not very strict; usually garden soil, composted barnyard manure, and river sand can each make up 1/3 of the mix. If it is too acidic, add some lime powder or plant ash; if too alkaline, add some aluminum sulfate or ferrous sulfate. In spring, after potting the osmanthus, water thoroughly, then move it to a shaded place for about 10 days to let it "adjust to the pot." During this period, do not fertilize. Only after growth resumes and new leaves grow should you water and fertilize. Flower pots made of purple clay pottery or glazed pottery are best, and colors such as purple or ochre are better, as they create a sharp contrast with the flowers and leaves and enhance the ornamental effect.

4. Pruning and shaping: For osmanthus styling, curved-trunk, slanting-trunk, or flowing styles are best. With a slanting tree form, dense branches and leaves, and a natural antique look, it is most enjoyable to admire. When in bloom, the rich fragrance fills the air and refreshes the heart. Osmanthus shaping generally uses a combination of wiring and pruning; the trunk can be wired into a curved or slanting form. Shaping and pruning of osmanthus should preferably be done after autumn. For plants that are very tall with very empty lower branches and a poor tree shape, cut off the entire top branches at 2/3 or 3/4 of the height. For plants that are "top-heavy," cut off the overly dense upper branches, leaving only the smaller lower branches. For plants with overly dense branches, thin them out. After flowering, do another round of branch trimming, cutting off leggy branches, dead branches, diseased and pest-infested branches, and dense weak branches.

5. Overwintering: Room temperature should be kept at 0-5°C, and relative humidity at 50-80%. In winter, the cold room should have good light, especially before the buds begin to sprout in early spring, when sufficient sunlight is even more required. In the following spring, in North China after Grain Rain (around Awakening of Insects in the Huang-Huai River basin), arrange to move potted osmanthus outdoors. After moving out, first place them together in a wind-sheltered, sunny spot outdoors, then later spread them out in rows so they gradually adapt to the outdoor environment.

6. Pest and disease control: Common diseases of osmanthus include leaf spot, sooty mold, algal leaf spot, root rot, and iron deficiency, which should be controlled according to the disease situation. Leaf spot, sooty mold, and algal leaf spot can be controlled by spraying 0.5 Bordeaux mixture or 5% carbendazim at 500-1000x dilution; for root rot, keep the soil loose and aerated, and do not let water accumulate; if root rot is caused by fungi, irrigate the roots with 200-300x amobam solution. Common pests of osmanthus include sawflies, whiteflies, mites, long white scale insects, and yellow stinging caterpillars. Sawflies, whiteflies, and mites can be killed by spraying 40% dimethoate at 1500-3000x dilution. For long white scale insects, besides manual brushing, during the first and second instar nymph stages, spray 40% omethoate at 1000x dilution or 40% fenitrothion at 500x dilution.

Osmanthus grafting methods

Mostly use 1-2 year old seedlings of privet (Ligustrum), small-leaf privet (Ligustrum sinense), or small-leaf ash as rootstock. Among these, grafting osmanthus onto privet has a high survival rate and fast initial growth, but the wound heals poorly, and it is prone to breaking off when exposed to strong wind or external impact.

1. Approach grafting:

Osmanthus grafting propagation generally uses the approach grafting method. Because privet has strong adaptability and is resistant to cold and waterlogging, small-leaf privet is mostly used as rootstock. The suitable time for approach grafting is April-June. The scion can be a robust two-year-old small branch about 0.7-0.8 cm in diameter, and the thickness of the rootstock is best equal to that of the scion. When approach grafting, place the rootstock pot close to one side of the mother plant so the graft can be brought together and fitted. Then, on branches of the mother plant and rootstock at equal height, select flat, smooth, node-free areas and cut an oval surface about 3-4 cm long on each, cutting down to the cambium and reaching the xylem. Then immediately bring the two cut surfaces together, align their cambium layers, wrap tightly with moist hemp strips, and cover with plastic film to maintain internal humidity. After the approach grafting operation is completed, the wound heals in about 2 months, and a tumor-like mass forms at the wound and tender roots grow out. When the new roots grow to 2-3 cm long, the scion can be cut away from the mother plant. The newly planted specimen only needs to be placed in a cool place, protected from sunlight, kept humid, and watered appropriately. If managed properly, it can bloom in the same year.

2. Besides approach grafting, cleft grafting and side grafting are also commonly used in production:

These two grafting methods are carried out around Qingming Festival. The scion should be selected from fully lignified, robust, disease-free 1-2 year old branches on mature trees, with leaves removed and petioles retained. For cleft grafting, before the seedlings sprout in spring, cut the rootstock off 4-6 cm above the ground and then graft. The thickness of the scion should match that of the rootstock, and the cut surface of the scion should be smooth. The key to successful cleft grafting is that the cambium layers of the rootstock and scion must be aligned and the binding must be tight. For side grafting, there is no need to cut off the rootstock; directly insert the scion bud into the rootstock, and cut off the rootstock after the graft succeeds. No matter which method is used, collect and graft the scions as quickly as possible. If scions are collected from other places, be sure to keep the scions fresh. It is best to choose sunny, windless weather for grafting. After grafting, check the survival rate, do a good job of supplementary grafting, bud removal, rootstock cutting, removing binding tape, water and fertilizer management, and pest and disease control.

3. Mound soil grafting:

Osmanthus mound soil grafting uses the cut grafting method. When grafting, first soak the scion for a full day and night so it absorbs enough water. Cut the rootstock off 3-5 cm above the ground, make a downward cut 2-3 cm on one side of the cut surface, cut the lower end of the scion into a slanted surface 2.5-3.0 cm long, and shave off some bark on the opposite side. Both cut surfaces must be flat, then insert into the rootstock so the bark layers fit closely together, bind with hemp fiber, smear the joint with wet mud, and finally fill and seal the lower part of the scion with moist sandy soil so that the upper end is exposed 2-3 cm. Be careful not to loosen the scion. After the graft survives with this method, the hemp fiber rots on its own, and there is no need to remove the rootstock.

4. Rootless grafting technique:

Reverse the normal order of cutting and grafting, that is, first graft the osmanthus bud onto a small-leaf privet cutting, then directly plant the grafted cutting into a prepared bed to root, so that the cutting and scion survive together. In this way, it avoids the problem of low labor efficiency from waiting for the cutting to survive and then grafting in the field. New shoots sprouting from the small-leaf privet need to be cut off promptly to ensure the normal growth of the 'Fodingzhu' osmanthus.

The above are the key points for potted osmanthus care and osmanthus grafting methods we have introduced for you. Is everyone clear now? For more home knowledge, please stay tuned.

How to Graft Osmanthus and Osmanthus Grafting Time

There are many methods for grafting osmanthus, such as approach grafting, cleft grafting, side grafting, mound soil grafting, and rootless grafting technique, etc. To graft osmanthus well, we can choose from these grafting methods the one we are more familiar with, so that osmanthus grafting is more reliable. Below are two grafting methods for osmanthus - approach grafting and side grafting - organized for you, hoping to be helpful.

Grafting osmanthus in early spring is better, as you can determine whether it has survived in the same year, which is good for management. Osmanthus can also be grafted in autumn; skilled grafters achieve a relatively high survival rate.

Generally, side grafting and approach grafting are used.

Osmanthus side grafting means trimming the rootstock before grafting. Cut off everything 6-7 cm above the soil surface, and make a slanted cut near the root crown, without damaging the pith. Use a 2-3 year old branch (without leaves) as the scion, about 10 cm long, preferably with 2-3 nodes. Then cut the scion base into an unequal-sided wedge shape, insert it into the cut in the rootstock so they fit closely, bind with plastic or hemp fiber, and then mound soil up to the top of the scion.

Osmanthus approach grafting first involves growing the rootstock in a pot. During the plum rain period in June-July, select a two-year-old osmanthus seedling branch similar in thickness to the rootstock and approach graft it while still in the pot. After it survives, cut it off before "White Dew." This is the new plant, and it can bloom in the same year.

About 20 days after grafting, osmanthus can survive and sprout. For plants that have not survived, if the suitable grafting period has not passed, supplementary grafting should be done promptly; if the suitable grafting

period has passed, then select and keep 1-2 new shoots on the rootstock to prepare for supplementary grafting the following spring.

After the grafted seedling survives, gently dig away the mounded soil, select and keep 1 vigorous new shoot for cultivation, and remove the extra new shoots. For rootstock suckers growing from the rootstock, remove them all early after the graft survives. This is because rootstock suckers and scion new shoots compete for water and nutrients, directly affecting the normal growth of the grafted seedling. If the rootstock sucker shoots grow beyond the scion new shoots, it often causes the scion to "regress buds," and the graft cannot survive.

When the new shoots of the grafted seedling reach 15-20 cm in length, stakes should be set up to secure them, in case wind breaks or bends them and causes poor tree form later. Mound soil around the base of the grafted seedling to prevent the graft union from splitting.

Throughout the entire growth period of the grafted seedling, attention should be paid to cultivation, weeding, and drought and waterlogging control. When the grafted seedling grows to more than 10 cm tall, apply diluted livestock manure water once to promote seedling growth; afterward, apply fertilizer once every month. A one-year-old grafted seedling can reach 30-40 cm in height in the same year, and up to more than 70 cm at the highest. It can be transplanted in the following spring, and after meeting the specification requirements, it can be released from the nursery for planting and use.