These durable spikes won’t break, crush or leave a dusty residue. Take the guesswork out of fertilizing. NUTRIENT RICH 10-4-10 FORMULA: Specially formulated to provide essential nutrients for all types of evergreen and fir trees ans shrubs, these 10-4-10 NPK Spikes provide 10% Nitrogen for virogrous, colorful needles and leaves; 4% Phosphorus for bountiful fruiting, coning and flowering; and 10% Potassium for strong roots.