Fruit from seedlings is variable and superior varieties are propagated by cuttings, marcotts or grafts. Grafted trees are better in windy exposed areas as cuttings or marcotts do not develop the strong root system of the seedling rootstock used in grafting.
Guavas have recently been recognised for their ellagic acid which is a polyphenol antioxidant and compare favourably in health benefits to the much touted pomegranate. It has exceptional levels of Vitamin C and good levels of Vitamin A, niacin, potassium and fibre. The Vitamin C content is highest in the skin and outer flesh so it is important to eat fresh, whole fruit to maximise the benefits. Recent studies have shown that these complex compounds are synergistic and are much more beneficial to health when consumed together in the whole fruit. We must not forget that these compounds have been made in Mother Nature's laboratory over many centuries and are much different to the many substitute supplements that are synthetically derived in a test tube by white coated people. There is an old saying ‘When we throw Mother Nature out the window she comes in the front door with a pitchfork.’
The growth of young trees is improved by applications of trace elements (particularly cooper, zinc and manganese) three times a year for the first two years of growth. The flavour and quality of fruit will be improved by weekly foliar applications of 1% potassium sulphate (10ml per litre) for seven weeks after the fruit has set. A high nitrogen organic fertiliser is beneficial after spring pruning to promote strong vegetative growth needed to support the flowering and fruiting cycle. Low nitrogen and high potassium organic fertiliser should be used at the commencement of the flowering cycle. Adequate water at flowering and during early fruit growth will limit fruit cracking and reduce some fruit abnormalities at maturity.
Inferior cultivars have many hard seeds, which make chewing difficult, with coarse, granular flesh of a pungent odour. Superior cultivars have a fine, creamy sweet flesh with small contained seed balls or low numbers of softer seeds in the flesh as well as a pleasant, unique guava aroma. Guava fruit will continue to ripen off the tree if picked at the right stage of maturity which is usually determined by slight changes to the skin colouration.
‘Northern Gold’, ‘Glom Sali’, ‘Hawaiian Pink Supreme’, ‘Mexican Cream’, ‘Giant Thai White’, ‘Sweet White Indonesian’, ‘Pear’.