Use a good quality soilless potting mix to fill large containers because it is lightweight and drains well; adequate drainage is crucial for successful container gardening.  When water does not drain from a container, water fills the soil air pores, and when that happens, roots can’t breathe or exchange gases. The plants will eventually die from lack of oxygen. If you are creating a container garden in colder climates such as USDA Zones 5 and lower, do not use soilless potting mix that contains moisture retention granules because they will freeze. A possible disadvantage to using a soilless potting mix is that it is very lightweight and dries out quickly. However, adding packaged pasteurized potting soil to the soilless mix at a ratio of one part soil to three parts soilless mix will provide more substance and better water retention. Though helpful, adding potting soil is not required. Never fill a container with garden soil. Garden soil is too dense and heavy, compacts easily, does not drain well, and it doesn’t provide proper aeration. Garden soil might contain pests that can contaminate your container with unwanted elements such as fungi, soil-borne adult insects and larva, and weed seeds. The advantage to using lightweight soilless potting mix can be significant, particularly if you ever have to move the container or are placing it onto a deck or balcony where weight can be an issue. A large container filled with damp soil and plants can become very heavy. Generally, the more soil a container has, the more it will retain water, and that can be a good thing. However, a large container requires quite a lot of to moisten the soil all the way to the bottom of the container. When you are filling and planting a large container with soil, it’s best to do so in its final location so that you don’t have to move it once you are finished planting. Thrillers are tall plants that add drama and a vertical element to a container. Think of a thriller as the star of the container. If your container is large enough, you might want to add more than one thriller. Examples of thrillers are tall annuals and perennials, ornamental grasses, and perhaps small trees and shrubs. Using trees, shrubs, or large perennials that can survive the winter in your area provides the added advantage of being a year-round container. Fillers are rounded, mounding plants that make a container look full and add mass to the container. Examples of annual filler plants are geraniums, begonias, marigolds, and vinca. Spillers are trailing plants that hang over the edge of a container to soften its edges Examples of spillers are many varieties of ivy, dichondra, and golden creeping jenny. While it’s common to use several different fillers and spillers in mixed containers, don’t hesitate to use only a single type plant in a container. For containers that are wider than they are tall, one low-growing ground cover like golden creeping jenny or a low-growing succulent can look stylish and interesting, particularly when planted in a spectacular container.

  1. Keep up with deadheading. While some flowering plants don’t require deadheading, many do require deadheading. It’s beneficial to remove faded flowers to keep the flowering plants in your containers looking neat, to encourage more blooms, and to discourage the plants from going to seed.
  2. Pinch back plants to encourage bushiness and prevent spindly plants. Coleus, persian shield, some varieties of petunias, and other branching plants benefit from pinching back to control legginess.
  3. Fertilize containers regularly throughout the growing season. Many large plants are heavy feeders, so use a diluted liquid fertilizer every other week to keep them healthy and well fed. With every watering, nutrients leech from containers so it’s important to maintain a regular feeding schedule.
  4. Make sure your plants are receiving enough water. Especially with large plants, foliage can act as an umbrella, and light rain or water from a hose can be shed before it has a chance to reach the soil. You’ll know that you’ve watered well when you see water seeping out of the drainage hole at the bottom of the container. If you don’t see water draining from the container, you have not watered enough. The only requirement for a container is that it must have drainage holes at the bottom, otherwise water cannot drain. Containers that are intended for outdoor use come with pre-made drainage holes. You might have to drill drainage holes in plastic containers that can be used either indoors or outdoors. If weight is a concern, consider purchasing a container made from fiberglass. They can be equally as fancy and beautiful as a hand-thrown terra cotta container. You don’t have to spend a lot of money to get a fabulous container. Very often, large containers made from terra cotta, fiberglass, wood, and ceramic are sold at local independent nurseries and garden centers, home improvement stores, home design stores, flea markets, thrift stores and garage sales.