Refer to the data below for how many spikes to use per pot size.Insert spikes into the potting mix midway between plant stem and pot edge, until the spike is just before the surface. Do not insert spike directly next to plant stem.Always water well after inserting plant food spikes.Reapply every 2 months.Wash hands after use.Pot diameter (cm): 10Number of spikes: 1-2Pot diameter (cm): 14Number of spikes: 3Pot diameter (cm): 20Number of spikes: 3-4Pot diameter (cm): 25Number of spikes: 4-5Pot diameter (cm): 30Number of spikes: 5-6Pot diameter (cm): For every 5cm pot increase above 30cm Number of spikes: + 1 spike