How should I fertilize container plants?
Written by
Benjamin Miller
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Fertilizing container plants is an individualized process that must be matched to nutrient requirements. Unlike garden plants, container-grown plants deplete their nutrients more quickly and need frequent replacements. You will need to know how to choose NPK ratios and apply them for healthy growth. Fertilizing correctly avoids deficiencies but also prevents fertilizer burn on the plants.
Flowering Annuals
- Formula: High-phosphorus (10-15-10) promotes continuous blooms
- Frequency: Apply every two weeks during growing season
- Method: Liquid solutions absorbed quickly through roots
- Tip: Stop feeding when temperatures exceed 90°F
Foliage Plants
- Formula: Nitrogen-rich (20-10-10) supports leaf development
- Frequency: Monthly applications from spring to fall
- Method: Slow-release granules mixed into topsoil
- Tip: Reduce strength by half for variegated varieties
Edible Plants
- Formula: Balanced organic options like fish emulsion (5-5-5)
- Frequency: Every three weeks until harvest
- Method: Soil drench avoiding leaf contact
- Tip: Stop feeding vegetables two weeks before picking
Application techniques play an important role in nutrient uptake. Always water the soil thoroughly before feeding to eliminate the risk of root burn. For liquid fertilizers, reduce solutions to half strength and apply them to moist soil. I use a syringe's measurement so I can be precise and not guess. Foliar sprays are effective for rapid nutrient increases; however, they should never be applied at midday.
By optimizing feeding schedules with seasonal adjustments, you can save on waste. Increase frequency and maximize feeding during spring growth spurts. Consider the application frequency during the summer heat above 85°F. Stop feeding six weeks before the first freeze to allow the plant to prepare for dormancy. Continue feeding in early spring, sparingly, as new growth breaks the surface.
Organic options such as compost tea provide gentle nourishment. Steep the compost in water for 48 hours, then strain it. Apply weekly during the growth cycle. Worm castings mixed into the top soil leach nutrients slowly. I even use banana peel tea for potassium lovers, such as those who love tomatoes.
Diagnosing deficiencies with leaf symptoms is an immediate corrective action. Yellow leaves are indicative of nitrogen deficiency, while purple tints are indicative of a phosphorus deficiency. Use formulations targeted to specific growth needs. Before applying any treatment, test the soil pH, as an imbalance can block nutrient uptake, regardless of the deficiency being addressed.
Read the full article: 10 Best Plants for Containers
