Despite the large number of seeds that can be obtained from guava fruits, seeds are not usually used for propagation even though they normally remain viable for many months and often germinate in 2 to 3 weeks. The main reason for this is that guavas cannot be depended upon to retain the characteristics of the parent tree. However, seeds are used to produce seedlings in breeding and selection programmers or to produce rootstock for grafting of desirable cultivars.

Normally fully matured seeds of the current season are used for sowing. The seedlings can be raised in the nursery or in polyethylene bags. Seeds are sown in a well-drained growing medium; more than 90% of the seeds should have germinated in 15-20 days. The seedling trees raised in the nursery or polyethylene bags can be transplanted in the field when they are six to eight weeks old. Seedling trees bear fruit of variable size and quantity, but such trees are generally long-lived.

Although it is not easy to graft guava, vegetative propagation is widely practiced to ensure that the plants are true-to-type and are early bearing. Several techniques are suitable to graft guava tress and they are listed below.

Nursery grown seedlings may be budded or grafted when stem diameter is 12-20 mm, with the greater diameter being especially suitable for budding . Budding is preferred over other grafting techniques, inasmuch as bud growth is faster and each bud on a scion or bud wood is a potential plant. The patch-bud technique gives good results. Success requires a vigorously growing seedling, where the bark peels readily, and well-prepared bud wood, with swollen axillary buds. A skilled propagator can achieve 90% or better success if it is done properly.

For grafting , the side grafting method is used most frequently. The scion wood or bud wood should be prepared approximately 10-14 days before cutting, by removing the leaves from branch. This practice encourages axillary buds to enlarge and greatly accelerates growth after grafting .

Wood that is shedding or has already shed its bark and is smooth greyish green in colour and without leaves gives good results in budding or grafting . Budding and grafting is useful if the rootstock has special attributes such as disease or nematode resistance or dwarfing.

Trees propagated using marcotting usually mature earlier than those propagated by bud grafting . The soil mixture used in marcotting consists of organic matter and topsoil at the ratio 1:2. This soil mixture needs to moist enough to form soil ball.

It is possible to use pruned branches as propagating material. Propagation can also be done from root cuttings. Pieces of roots (except the smallest and the very large) are first cut into 12.5-20 cm lengths. These are then placed flat in a prepared bed and covered with 5-10 cm of soil that must be kept moist.

One of the problems with budded and grafted guavas is the production of water sprouts and suckers from the rootstocks. But these can be easily pruned off.

Micro-propagation using nodal explants from mother trees has been reported from India with 70% success in transplantation (Soetopo, 1992). This micro-propagation technique is as yet not very popular partly because it is easier to propagate guava plants via conventional grafting methods.

Reference: Soetopo, L. 1992. Psidium guajava L. In. Verheij, E.W.M and Coronel, R.E. (eds). Plant Resources of South-East Asia 2: Edible fruits and nuts. PROSEA Indonesia : 266-270