Tips on Feeding Container Plants

Credit: Brand X Pictures / Home and Garden / Alison Miksch

Feeding container gardens

Feeding container plants and choosing fertilizer

Use a good controlled-release granular fertilizer in your containers – it can be mixed into the soil at the time of planting or can be sprinkled on top of the soil after planting. Use about 5 mL (1 tsp.) for a 4.5 L. (1 gal.) pot, 10 mL (2 tsp.) for a 9 L. (2 gal.) pot and 15 mL for a 22.5 L. (5 gal.) pot.

(Note: Be frugal when applying granular fertilizer to the surface of the soil. Too much can burn your plants, so use it sparingly and always water well as soon as it is applied.) Controlled-release fertilizers respond to temperature and moisture changes and are designed to release when plants are in active growth. They keep plants well fed and eliminate the need for mixing and applying soluble fertilizers.

Container Plant Fertilizer Recommendations

There are differing opinions where feeding is concerned. It is generally recommended that container plants that are not supplemented by a time-release fertilizer be fed every two weeks using a liquid or water-soluble fertilizer according to the rates recommended on the label. A flowering-plant fertilizer, such as 15-30-15, is a good choice.

Note: How much and how often you feed depends on the plants in your care. Perennials and herbs, for example, don’t need to be fed as frequently as summer-flowering annuals. For perennial container plantings it is important not to overfeed, especially if you are not able to flush the pot with water from time to time, as overfeeding can cause a build-up of salts around the roots and result in serious damage.

“Mature, flowering summer annuals grown in pots (June/July) require daily feeding. This often shocks first-time gardeners as they have been warned about overfeeding. However, daily watering of root-filled containers leaches out the nutrients. Add a few drops of liquid organic fertilizer or a pinch of 20-20-20 every time you water and you’ll be rewarded with glorious flowers right through to the fall.” – David Tarrant

Do not apply fertilizer to dry, wilted or sick container plants. Water them well, and don’t resume feeding until they have recovered.