Learning the differences between fertilizer and mulch can help your perennials thrive. Learn the basics here:

Fertilizer
The application of a complete fertilizer can help encourage perennial plant growth, as well as maintain the health and improvement of a plant. This crucial agent must contain (in varying proportions) these three plant nutrients: nitrogen, phosphorus and potash.

Organic or slow-release fertilizers are particularly suited to perennials since the nutrients are released over the full growth period. Apply fertilizer by hand per package directions in early spring, just as growth becomes apparent, and before mulching. Avoid letting it come in contact with foliage. Alternatively, use a complete inorganic fertilizer with an analysis such as 4—12—4.

From late spring to early summer the plants can be fed every three or four weeks with a fast-acting liquid foliar spray.

Mulch
Mulch, which is an organic layer over the soil, conserves moisture by reducing evaporation. A mulch also serves many other purposes. It prevents compacting, improving the quality of both clay and sandy soils. It helps to keep water from spattering the undersides of leaves, thus lessening the spread of soil-borne fungous disease. It also helps to suppress weed seedlings. Most importantly, as the organic materials break down, nutrients are added to the soil.

Apply mulch in late spring after the ground has been weeded, but before growth is advanced. In dry weather, soak soil before mulching. It is best to cover the planting bed completely. But if this is not possible, it is better to apply a thick mulch around some plants than to spread it thinly over the whole bed.

Watering should not be necessary if the bed has been mulched, except during prolonged dry spells. If watering is needed, use a sprinkler that gives a steady and even spray, so that the water penetrates deeply.

by the Editors of Reader's Digest