When Does Black Locust (Robinia pseudoacacia) Bloom and Bear Fruit, How Many Years Until It Flowers After Planting, and How Does It Differ from Chinese Scholar Tree?

Black locust, also known as false acacia. Black locust flowers are edible. The honey produced from black locust flowers is very sweet, and honey yields are also high. Cultivated varieties include Hongsen locust, red-flowered black locust, golden-leaf black locust, and others. So when does black locust bloom and bear fruit? How many years after planting will it flower? And how does it differ from Chinese scholar tree? The details are compiled below:

When does black locust bloom

Black locust (Robinia pseudoacacia) takes about 3 years from planting to bloom, and enters full bloom after about 5 years. The flowering period is April to June, and the fruiting period is August to September.

Planting methods:

1. Irrigation. Do not irrigate after sowing until the seedlings have emerged completely. After emergence, when soil moisture is moderate, loosen the soil and cultivate in time to raise soil temperature and promote germination. Irrigating too early, when soil moisture is too high and soil temperature is low, easily causes seedling stagnation or yellow-leaf disease. On the basis of repeated loosening and cultivation, the first irrigation can be given in early June, and thereafter under normal conditions irrigate once every 20d. After irrigation in early July, pause for a period to promote lignification of the seedlings and enhance their overwintering ability, then give the final winter irrigation in late November.

2. Topdressing. After the black locust seedlings are thinned to a stand, carry out the first topdressing together with the first irrigation, applying urea at 45~75kg/hm^2; at the end of June, together with irrigation, apply a compound fertilizer mainly of nitrogen and phosphorus 2 times, at 75~195kg/hm^2; stop fertilizing in early August. It is best to plow in winter and harrow in early spring, applying 3000 jin to 5000 jin of decomposed base fertilizer per mu. Spring land preparation should be done early, with deep plowing (over 25 cm), fine harrowing, and leveling. While preparing the land, mix 15 jin of black vitriol (ferrous sulfate) powder per mu with 1 jin of 5% phoxim, then blend in 40 times its volume of fine soil, and spread it into the ground for soil disinfection.

3. Loosening soil and weeding. The nursery land should be cultivated promptly after irrigation or rain, regularly keeping it loose and free of weeds.

4. Cold protection for overwintering. One- to two-year-old black locust seedlings are susceptible to damage from autumn frost and dry spring winds, which causes the aboveground parts of the seedlings to dry up, so one-year-old seedlings should be dug out after autumn for autumn planting or heeled-in overwintering, and provided for planting in the second spring.

5. Transplanting to grow large seedlings. To grow large seedlings needed for roads, courtyards, urban greening, and so on, Yuanzhou District generally transplants from late April to early May. Transplanting density mainly depends on the seedling cultivation specifications and years; generally, for four-year-old transplanted seedlings, a spacing of 50cm×100cm is suitable. The longer the seedling cultivation period, the greater the transplanting spacing should be. Black locust transplantation mostly uses hole planting; before transplanting, the aboveground parts should be cut off, and split or damaged roots should be trimmed away. The root length should be kept at 20~30cm, the seedling roots should be dipped in slurry for planting, and the planting depth should keep the top of the root collar level with the ground surface. After transplanting, the seedlings should promptly receive tending work such as watering and topdressing, loosening soil and weeding, and cold protection for overwintering; especially for stumped seedlings, work such as removing tips, wiping buds, and pruning should be done well, selecting and keeping healthy, upright branches as the main trunk.

How black locust differs from Chinese scholar tree

Black locust has thorns on its branches, but Chinese scholar tree does not.

Black locust leaves turn gray after withering, while Chinese scholar tree does not show this phenomenon.

The raceme of black locust droops, while the raceme of Chinese scholar tree is upright.

The flowers of black locust are larger than those of Chinese scholar tree.

The pod of black locust is linear, while the pod of Chinese scholar tree is bead-like.

The seeds of black locust are smaller and have black spots; the seeds of Chinese scholar tree are about the same size as cowpea seeds and black.

The hilum of black locust seeds has a gap in the middle, while the hilum of Chinese scholar tree seeds does not show this phenomenon.

In addition, Chinese scholar tree is easily harmed by the Chinese scholar tree looper, while black locust is not harmed by the Chinese scholar tree looper.

Chinese scholar tree has pointed leaf tips, green branchlets, shallow trunk fissures, terminal panicle inflorescences, and bead-like pods.

Black locust has concave leaves, non-green branchlets, deep trunk fissures, axillary inflorescences, and pods that are not bead-like.