How to Plant Olive Trees? The Latest Planting Techniques and Methods Tutorial
The olive tree is a subtropical evergreen tree of the genus Olea in the family Oleaceae, native to the Mediterranean coastal regions of southern Europe. It has been widely introduced and planted in China across 15 provinces and regions south of the Yangtze River basin down to Guangdong and Guangxi, with Hubei, Sichuan, Yunnan, Guizhou and Shaanxi being the provinces with the most plantings. It has extremely high planting value. Let us take a look at olive tree planting techniques together!
Growth Habits of the Olive Tree
The olive tree prefers warmth. During the growing season it needs suitably high temperatures to grow vigorously and bear good fruit. Areas with an annual average temperature above 20°C and no severe frost damage in winter are most suitable for its growth. In winter it can tolerate short periods of low temperatures down to minus 3°C, but when the temperature drops below 4°C severe frost damage occurs. It can grow normally in areas with 1200-1400 mm of rainfall. It has broad adaptability to soil. It can be cultivated along riverbanks, on hills and mountains, and in red-yellow soils and gravelly soils. As long as the soil layer is deep and drainage is good, it will grow well.
Propagating Olive Trees by Grafting
1. Advantages of grafting: Olive trees grown from seed take 6-8 years to enter the fruiting stage, and the plants are tall, inconvenient to manage, and have a relatively large coefficient of variation. Grafting can advance fruiting by 3-4 years and has the effect of dwarfing the plant and accelerating the improvement and renewal of superior varieties.
2. Grafting time: For young seedlings, the best time is from February to the end of March, on sunny days when the temperature is stable above 15-16°C, that is, when the tree's sap begins to flow. For mature large trees, the root system is deep and soil temperature rises relatively slowly, so the top-grafting time can be postponed accordingly, extending to April-May.
3. Scion treatment: The scion is cut when the spring shoots begin to sprout. From vigorous, high-and-stable-yielding middle-aged trees, select autumn scion branches that have short internodes, plump buds, thickness comparable to the rootstock, and that grow on the outer part of the canopy. After cutting, immediately remove the leaves, wrap and bundle them in a damp cloth, and put a plastic bag over the outside to prevent the scion branches from losing water. If they need to be stored for a longer time, pay attention to the humidity inside the bag and the supply of nutrients to prevent mold and rot, and take care during transport to protect the buds and cortex from damage.
4. Grafting methods: Select scion branches with 2-5 buds and mainly use tongue grafting and cut grafting. In order to reduce the oxidation of tannins in the wound and the problem of bleeding, the grafting must be done quickly. Align the cambium of the rootstock and scion, insert firmly, seal and wrap tightly, and pull the single layer tight at the buds. For mature trees, mainly use inlay grafting and cut grafting, while keeping part of the canopy as sap-drawing branches to protect normal growth of the tree.
5. Removing the film and wiping out shoots: The wound-healing ability of olive trees is relatively slower than that of other fruit trees. With degradable film, removal is normally unnecessary; for a few that are tied too tightly and need to be released, the film should only be removed after the meristem tissue at the graft union has completely healed and become firm, so as to ensure the smooth growth of the scion buds. The rootstock easily sprouts adventitious buds, which should be wiped out promptly to reduce adverse effects such as competing with the scion branches for nutrients and occupying space.
Propagating Olive Trees by Seed
1. Seed treatment: For olives kept as seed, the fruit must be allowed to fully develop and mature, and is harvested around late October to November, when part of the outer shell of the seed pit turns a pale red-charcoal color. Mix fresh olives with table salt at a weight ratio of 10:1, pour into a vat, tread with the feet until the flesh and pit separate, then soak in clean water for 7-8 hours, and afterward tap lightly with a wooden hammer to extract the pits, separating the flesh from the pits.
2. Stratification in sand storage: Olive seeds need stratification to complete the after-ripening stage. Choose a wind-sheltered, cool indoor location and stratify with clean river sand. The humidity should be such that when squeezed in the hand it forms a ball without dripping water, and when released it breaks apart into small clumps. The ratio of seeds to river sand is 1:3, with one layer of river sand and one layer of seeds, stacked alternately in this way for 4-5 layers. During stratification, check regularly, control temperature and humidity well, and prevent mold, rot and excessive drying.
3. Sowing method: Sow in February-March of the following year. Before sowing, soak the seeds in warm water for 5-6 hours, which helps uniform sprouting and facilitates management such as fertilizing, spraying and watering. If preparing to graft and propagate on seedbeds in the original orchard site, the plant spacing is about 12 cm × 15 cm; too wide reduces soil utilization and encourages vigorous weed growth; too narrow makes grafting inconvenient and causes excessive spindly growth of the seedlings, which is unfavorable for strong seedlings. For selling seedlings or transplanting small seedlings, sowing can be dense. After evenly broadcasting 300-400 seeds per sq m, press the seeds into the soil with a wooden board, cover with 2-3 cm of fine soil, cover with rice straw, and do a good job of keeping warm and moist.
4. Seedling cultivation: Direct sowing and raising seedlings in the orchard site gives a high survival rate and is convenient to manage. The seedlings emerge 40-50 days after sowing. Generally, mainly apply decomposed human and livestock manure frequently, keep the seedbed at suitable temperature and humidity, and pay attention to pest and disease control. Management requirements for transferring into nutrient bags are very strict, but the survival rate of seedlings planted out from the nursery reaches 97%-100%, which is deeply recognized by the vast number of fruit growers. Several main steps should be noted in propagation. The nutrient bags measure 25 cm long and 15 cm wide, to prevent or reduce the main root growing too fast during the seedling stage and piercing out of the nutrient bag.
5. Transplanting seedlings: Apply sufficient base fertilizer of culture soil in the bottom layer of the bag. When the small seedlings have 2 leaves and 1 heart, transfer them into the bags for cultivation. Those with long main roots can be coiled and planted appropriately shallowly. Arrange 8-10 bags as one row, with every two rows as a small line and a 10-15 cm gap in between, placed into beds. Finally, fill the gaps in the middle and around the sides with crushed soil to prevent water loss from watering and aging of the plastic bags from sun exposure.
6. Seedling management: Sprinkle a small layer of crushed wood shavings, peanut shell bits, etc. on top of the bag soil, which has effects such as retaining moisture, keeping warm and reducing weed growth, and is very beneficial to the survival and growth of the seedlings. In summer, with high temperature and drought, set up shade. When pulling weeds or loosening the soil, take care to prevent root damage.
Olive Tree Planting and Management
1. Site selection: The olive tree has the characteristics of preferring warmth and having strong drought resistance. Places with an average annual temperature of 18-20°C and annual rainfall of 1200-1600 mm are all suitable for olive growth. The best site is one with deep, loose soil containing abundant organic matter, or sandy loam. The orientation should not have strong western sun exposure or closed mountain hollows prone to cold air and frost. In combination with the actual conditions of the site, choose hillside land or terraced land with convenient transport, abundant and pollution-free water, and relatively flat terrain for planting.
2. Planting method: Choose a season with ample rain for olive planting. When taking out seedlings, minimize root damage and promptly remove 2/3 to 3/4 of the leaves. For young saplings without soil, if conditions permit, seal and wrap the trunk with degradable film to reduce water evaporation. The planting holes should be dug deep, and when planting, bury deeply or mound up soil high; after confirming survival, appropriately dig away part of the mounded soil. For sites with abundant water, pour water into the hole and mix into mud, or better, put in rice paddy mud, place the roots in the mud for planting, and then cover with soil. At planting time, do not apply inorganic fertilizer or inadequately decomposed organic fertilizer, to prevent root damage affecting survival.
3. Care measures: Insert bamboo stakes to prevent livestock damage and take shade measures. The tree basin can be covered with plastic film or rice straw and other measures to maintain moisture so as to pass through summer smoothly.
4. Training and pruning: The olive tree has strong growth vigor, which easily causes excessive vegetative growth and affects reproductive growth. Generally, adopt measures to weaken apical dominance, mainly using light pruning and thinning pruning, or appropriate heading back, to promote branches at all levels to form an even and compact canopy. Olive flowering and fruiting have the characteristic of an outer-edge advantage, and most of the fruiting branches each year develop from the previous year's summer and autumn shoots. When pruning after fruit harvest, pay attention to cultivating the summer and autumn shoots on the outer part of the canopy, to promote fruiting branches that sprout from after the Beginning of Spring to before the Awakening of Insects, whose fruit-setting rate is the best. In production, flower-promoting measures such as water control, root cutting, girdling and chemical regulation are also combined; girdling treatment should be operated cautiously and is not recommended.
5. Fertilizer and water management: In cultivation, the fertilization time and amount are determined according to tree age, tree vigor, fruit load, soil fertility and so on. Generally, apply pre-flowering fertilizer in March, using medium-release fertilizer combined with farmyard manure. Apply fruit-swelling fertilizer in August-September, with topdressing of quick-release fertilizer and plant growth regulators. After fruit harvest, heavily apply farmyard organic fertilizer and supplements of major elements such as N, P, K and Ga, and as far as possible do turning of the soil, deep application and covering. In rainy weather or dry clear weather, drain or irrigate promptly to ensure normal growth of the tree, especially ensuring a suitable water supply during each shoot-sprouting period and fruit-swelling period.
6. Harvesting and freshness preservation: Harvest at the appropriate time according to use and market demand. Olive fruits contain more tannins, and after harvest easily lose water and shrivel. When picking, harvest according to sales, processing volume or orders. At the same time, take care to protect the terminal buds of the fruit branches so they can sprout the following year's fruiting branches, and as far as possible pick lightly, load lightly, and transport without damaging the fruit. Maintaining suitably stable temperature and humidity is the key link in olive freshness preservation. Then process according to different procedures based on use, to obtain the best economic benefits.
7. Pest and disease control: Compared with other fruit trees such as citrus and jujube, olive trees have relatively lighter diseases, mainly including anthracnose, gummosis and tree gall disease. The main pests include the star-room psyllid, the small yellow leaf-roller moth, the black spiny whitefly, scale insects of the Diaspididae, and longhorn beetles. Measures of “prevention first, integrated control” should be adopted. [For diseases, at the early stage of new shoot leaf expansion or disease onset, spray with 70% thiophanate-methyl 1500x solution or 50% carbendazim 800x solution for control. For pests, spray with 90% trichlorfon 1000x solution + 10% imidacloprid 2000x solution + 40% chlorpyrifos 1500x solution, or 5% fipronil 1500x solution + 5% acetamiprid 12500x solution for control. For longhorn beetles, combine with manual capture and kill, inserting cotton dipped in the pesticide solution into the insect tunnels to fumigate and kill them.