City Offers Advice and Deals for Container Gardening

City Offers Advice and Deals for Container Gardening

By Karen Klinger

If you want to do some gardening now that spring is here, but have little space, or no yard or you don’t have a plot in one of Cambridge’s community gardens, there’s another alternative: grow plants in containers.

As a standing-room-only crowd of 150 learned during a recent workshop co-sponsored by several city agencies, including the Department of Public Works (DPW), almost any plant can be grown in a container as long as it receives the right mix of sun, food and water.

In fact, as workshop leader Clarinda Spinelli noted, there are some real advantages to using containers: plants are less susceptible to pests such as slugs and snails than they are in the ground; the containers can be moved around to increase (or decrease) the amount of sunlight the plants are exposed to; they can be moved inside if a frost is predicted; and they can be used to decorate areas ranging from window sills to patios and balconies.

Spinelli, a landscape administrator at the DPW who has been container gardening for 20 years, said another advantage is that if you move to another dwelling, you can take your plants will you, as she has done.

At the workshop, she used a large galvanized steel tub with drainage holes drilled in the bottom to demonstrate gardening techniques, but she said commonly used containers also are made from clay, wood, stone and synthetic materials such as plastic and fiberglass. They all have advantages and disadvantages: wood blends well with plant material but can rot if left untreated, clay is porous but prone to frost damage, metal is frost-proof but can rust, stone is attractive but heavy and synthetics are generally durable but do not always age well.

It goes without saying that the size of the container will determine what types of plants you can use and how many. Most containers have a capacity of between 15 and 120 quarts, and they generally need to be deep enough to accommodate between 12 and 18 inches of potting soil.

To help with drainage, Spinelli recommends placing filler such as gravel, broken pieces of pottery or Styrofoam packing peanuts at the bottom of the container and covering it with filter fabric of the type sold in rolls at garden centers. Then add enough potting soil to fill the container to about two inches from the rim.

She said among the reasons for using potting soil is that it is sterilized, so that it does not contain pests or other contaminants, and it has material including vermiculite which both retains moisture and facilitates drainage, so it can be wet but not soggy.

Before choosing which plants you want to grow, Spinelli said it’s a good idea to do some research to find out what their requirements are in terms of sun or shade, whether they can tolerate cold weather or like it hot and how much watering they will need, keeping in mind that soil in containers can dry out relatively quickly.

Among her other suggestions:

  • Determine how large each plant will be at full growth and arrange them accordingly as you plant them. In her demonstration, Spinilli used seedlings of various herbs and lettuce, placing a bay leaf plant in the middle of her container because it will become taller than the others at maturity.
  • Mix granular fertilizer in with your potting soil (if it does not already contain fertilizer) and use a liquid fertilizer on your plants as frequently as every-other watering. If you use organic fertilzer such as blood meal or fish emulsion, remember that the scent could attract pests such as squirrels.
  • Speaking of squirrels, while they generally will not treat your container garden like a salad bar, they can cause damage with their digging. For other pests, ringing a container with sand is a good way to deter slugs (“Their little bodies don’t like sand,” said Spinilli) and including some plants such as mint, sage and garlic creates a natural repellant.
  • To ensure proper drainage, get the containers off the ground slightly by putting them on blocks or bricks or on wheels, so they can be moved around easily.

Spinelli said she thinks that overall, “Gardening is a lot like cooking. When you are beginning, you do everything carefully, you measure and follow the rules. But as you get more experienced, you just wing it.”

There are other tips on container gardening at the DPW website: The department also has some deals for gardeners:

Special offer on rain barrel purchases--Through a grant from the state Department of Environmental Protection, the DPW is offering 55-gallon rain barrel collection systems for $62.95 (off the regular price of $119.95) to the first 100 people who apply before May 18 and $72.95 thereafter. For more information, contact Catherine Daly Woodbury at or call 617-349-4818.

Get a rodent-proof composter--The DPW is also selling composters for $50 at its office at 147 Hampshire St. during regular operating hours. In addition, the city is holding a series of seminars on composting. For information, contact Recycling Director Randy Mail at or call 617-349-4866.