Question from Tod:
Just bought the new edition of your book (I’ve had the 2nd edition for years now and refer to as my garden bible!). I am trying to go 100% organic in my garden and wanted to ask about fertilizing my Canary Island Date Palm. It’s about 20 ft. tall now and doing well but I have used the Palm spikes in the past. Will mulching and compost do the trick or are there other products out there similar to the non-organic palm spikes? I do have some pygmy palms and use Dr. Earth palm food but wasn’t sure if it would be good for the Canary Isl. Palm. Appreciate your time! You are the best… Thank you, Tod
Answer from Pat:
This is a lovely question and it has two answers, the first answer is a scientific one and the second based on observation and history. First for the answer based on scientific experiments here in America and also in the Mediterranean region and the Near East—particularly Israel and Saudi Arabia—where date palms are extensively grown for their fruit. Even though the edible date palm (Phoenix dactylifera) is a different species from your Canary Island date palm (P. canariensis), the requirements should be similar. Experiments have shown that palm trees are big eaters requiring a balanced fertilizer containing nitrogen, phosphorus, and potassium in roughly equal proportions along with trace elements especially iron, manganese, and magnesium. They also need calcium which is abundant in most of our local soils. When palms lack manganese, leaves shrivel on the ends and bear black stripes. When deficient in magnesium, leaves go brown and the meristem layer stops growing. Palms have been known to die from magnesium deficiency. All good palm fertilizers thus contain trace elements usually with more iron, manganese, and magnesium than others. (Read the labels to make sure.) Additionally, palm trees need fertilizer on a regular basis during growth, thus those growing in sandy soil (as often is true in desert regions) need fertilizing more than once a year during the warm months. This is why many gardeners have used slow-release fertilizers, such as the palm spikes you mention, to stretch out the fertilizing over a longer time span. (Manganese palm spikes are available also.) Fortunately for organic gardeners most organic fertilizers are slow-release by their very nature.
Thus, any good organic fertilizer recommended for palms such as Dr. Earth Palm Food should do the trick, but you may need to use more of it than stated on the label. Another way to go if you wish would be to mix up your own concoction of ingredients. To make your own fertilizers for palms, check this website under “Fertilizers” and see the chart called “Generic Fertilizers and Soil Amendments” for ideas. For example, blood meal provides strong nitrogen (though it is fast acting) and it also contains iron. Palms love it. Seaweed is a good way to provide trace elements and so is humic acid. “John and Bob’s Soil Optimizer” is beneficial to palms–it contains humic acid that releases the iron and other trace elements already existing in clay soil. Products containing mycorrhizal fungi and rhizobia also have been found to be beneficial to palms. Biosol Mix 7-2-3 is among all-purpose organic fertilizers since it contains rhizobia and rock powders, including bentonite for calcium. Rock dusts are one way to provide trace elements to soil that is deficient in specific elements, but it is unwise to add rock dusts without having a soil test by a reputable company to make sure your soil is deficient. In general if a palm is growing at a good clip looks good you can count on the fact you are doing the right thing and it’s getting what it needs.
Now to consider manure and compost. Homemade compost teams with beneficial organisms, including rhizobia, and thus it benefits all plants, including palms. Manure is an ancient generic fertilizer for trees of all kinds. Tropical trees in rain forests are fed with droppings of monkeys and whatever other animals roam the forests in which they grow. On the northern hemisphere, we often see herds of cattle, deer, sheep, and other herd animals sheltering under trees. Many of the ancient trees of England doubtless owe their health and size to large number of cow pats one sees under their shady branches. While hiking through England, one may find that the spreading tree on a hilltop that looked like a perfect picnic spot from afar has been rendered inhospitable by a heard of cows that previously thought the same thing. Historic drawings of date palm groves show hundreds of camels sheltering in their shade. While traveling in Africa I once saw a camel market where thousands of camels stood in the shade of date palms as men haggled over prices. Cattle and goats also seek shelter under date palms. Thus it stands to reason the ancient fertilizers for palms were manures just as we can imagine also that cycads (though they are not palms) thrived on dinosaur dung. Thus, in my opinion a layer of horse or other manure spread under the shade of your Canary Island date palm in fall would do no harm and probably would do it a great deal of good as the winter rains washed the goodness into the ground.
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