Saturday | April 18, 2015
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Garden Guy: Placing different fruit on the same tree

Different varieties of the same species of fruit tree can usually be grafted together on the same tree. This is often done to extend the harvest period.

As an example, if the Kahaluu variety of avocado were grafted onto a Sharwil avocado, the fall/winter picking season for Kahaluu would be extended into the spring by the addition of the Sharwil variety (winter/spring). This is particularly advantageous for homeowners with small property lots where space is a premium.

Furthermore, plants in the same genus, but of a different species, can often be grafted together. Many different citrus species (lemon, orange, grapefruit) can be put onto one tree. One word of caution, lemon trees are vigorous growers. When a lemon is grafted onto a slower growing orange tree, for example, care must be taken to prune the lemon, or else it will quickly outgrow and overgrow the orange.

Plants belonging to different genera are less successfully grafted, although there are some cases where this is possible. For example, quince, genus Cydonia, may be used as a dwarfing rootstock for pear, genus Pyrus.

Plants of different families cannot be grafted successful.

In addition to citrus, many deciduous fruit trees are grafted together. One tree can provide a harvest of peaches, nectarines, plums and apricots.

Which fertilizer is best?

I discussed this subject in the past, but it is worth repeating.

All fertilizer packages will have three numbers printed on them, 16-16-16, 10-20-10, etc. These numbers denote the percentage of the three primary plant nutrients, nitrogen (N), phosphorus (P) and potassium (K).

For example, 10-20-10 would contain 10 percent nitrogen, 20 percent phosphorus and 10 percent potassium. In addition to these complete fertilizers, some contain a single nutrient, such as urea (containing 45 percent nitrogen), while others contain a double nutrient such as ammonium phosphate, which is 11 percent nitrogen and 48 percent phosphorus.

Certain plants require a higher percentage of a particular nutrient.

Bananas like potassium, something close to 10-5-20 should be applied, especially in potassium deficient soils. A lawn, which is grown for its foliage and not fruit or flowers, along with other ornaments grown for foliage, will basically need nitrogen, with P and K added occasionally, depending on soil analysis.

Vegetables, in general, need a high phosphorus fertilizer, such as 10-30-10. Specialty products, such as citrus or palm fertilizer, are good products but generally more expensive. In most cases, a balanced fertilizer such as triple sixteen (16-16-16) will work just as well.

Here are some other things to keep in mind when it comes to fertilizers:

• Nitrogen is important in the photosynthesis process and for many growth and developmental activities. Nitrogen moves readily in the soil to the plant’s roots. But this also means with heavy rains, it can readily leach beyond the root zone. Deficiency symptoms include stunted growth and chlorotic (yellow) and pale green leaves. Plants with excess nitrogen will exhibit dark green leaves, reduced yields and delayed maturity.

• Phosphorus stimulates early growth and root formation and promotes seed formation. Soil phosphorus is often tied up chemically in relatively insoluble compounds and does not move well in the soil. Although some Hawaiian soils have adequate level of phosphorus, many are very low in this element.

• Potassium is involved with cell division, starch and protein synthesis and sugar movement within the plant. It increases size and quality of fruits and vegetables and increases disease resistance. Potassium is usually abundant in soils, but much of it is tied up in soil minerals and is unavailable to plants. Soils in high rainfall areas are usually low in potassium.

Gain more knowledge about gardening in my new book, “Ask the Garden Guy, Science Based Answers to Garden Questions.” The book is available at local stores on the Big Island and Maui.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at You also can visit his website at


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