Tree fertilizer spikes are sold online in the US in two kinds: complete formulas for palms and citrus, and single nutrient spikes for iron, manganese, magnesium, and potassium deficiencies. TreeHelp makes both in the USA, with individual spikes listed at $1.85 and cases of 10 for most types and 50 for palm spikes.

Why are spikes used instead of surface fertilizer?

Because a spike places slow release nutrients below ground, near the feeder roots, where water cannot wash them away. Fertilizer scattered on the surface leaches quickly in sandy or heavily watered soil, while a spike keeps feeding from the same spot for months.

Which spikes are made for palms and citrus?

Complete spikes built for each. Early in spring, ideally, TreeHelp Complete Citrus Spikes, a citrus formula with 13 percent sulfur, are placed underground near the feeder roots and feed the tree for up to a full year. Two TreeHelp Complete Palm Fertilizer Spikes for a 6 inch trunk, rising to 10 for an 18 inch trunk, are hammered into the ground around a palm and watered in, supplying potassium, manganese, and magnesium for up to 12 months.

Which spikes treat a single nutrient deficiency?

Supplement spikes matched to the missing nutrient. Where a complete spike feeds everything, the TreeHelp Iron Spike targets iron chlorosis, yellow leaves with dark green veins, and is driven into the soil around the tree, where it releases iron and lowers the pH so roots can take it up.

Frequently Asked Questions

How soon do iron spikes show results?

Usually within 30 to 90 days, with the full effect normally seen the following growing season.

Are there spikes made for maples and birches?

Yes. Manganese supplement spikes for maple and birch, with 20 percent manganese sulfate and 16 percent sulfur, address yellowing in high pH soil.

Which trees are most often short of iron?

Pin oak, silver maple, and white pine are among the trees most often affected.

Do palms need supplement spikes as well?

Only when a specific deficiency shows. Potassium spikes treat yellow, orange, or brown flecks on older fronds, and magnesium spikes treat yellowing between the veins of older fronds.