Container Gardening 101
Tips and techniques for gardening in containers, hanging baskets and window boxes.
Container-grown plants can be an addition to an already flourishing landscape or a garden all by themselves. By planting in nursery pots, buckets, whiskey barrels, grow bags, or whatever else you find around the house, you’ll be adding aesthetic interest and practicality to your yard and home.
Container gardening is useful when…
- you want to move warmth-loving plants into the house for the winter.
- controlling the soil quality is desired.
- there isn’t much space available.
- you want to grow fresh, yummy herbs and veggies (or pretty flowers) year-round.
- adding height, texture and variety to the yard is important.
When selecting plants, you need to consider both what you want and what the plants need.
What You Want in a Plant
Almost anything can be grown in a container, even many trees! But, before you rush out to the nursery to buy whatever suits your fancy, take a moment to think about what you want your container garden to achieve.
- Are you looking to grow foodstuffs such as vegetables or herbs?
- Do you want to add color to a drab garden?
- Does your yard need height and texture?
- Is your growing season short and you are looking for something that can come inside?
Although the container gardening field is wide open, some plants are better suited to pots than others. These include:
If you are taking an aesthetic approach, look for plants that:
- Balance and contrast each other
- Are suited to the size of the container
- Suit your color tastes
- Provide a focal point
What a Plant Wants
After you’ve thought about what you want, consider what you can provide the plants given your environment, space and time commitment. Of course, plants need light, food, air and water, but the quality and quantity varies from plant to plant. (Read more about plant requirements here.)
Read seed packets, plant descriptions or online references and then grow plants with similar requirements together.
Find out how big your plant(s) will be when mature and make sure your container can accommodate that. Dwarf varieties usually do well in containers since they are small by nature.
Container plants do best in a potting mix rather than in garden soil which can compact easily. Often garden soil contains weed seeds, pests and other critters you don’t want in your containers.
When purchasing potting soil (not really soil at all) read the package carefully. Instead of buying something labeled “topsoil” or “compost” which could be made of just about anything, invest in high quality organic potting soil.
If you choose to make your own, find a good recipe and experiment. A classic soil-based mix is:
- 1 part peat moss or mature compost
- 1 part garden loam or topsoil
- 1 part clean builder’s sand or perlite
Watering plants in containers is different than watering plants directly in the soil. Potting soil is often less dense than garden soil and thus holds less water. Additionally, the pot restricts the amount of soil to hold water. And because the pots are above ground, they don’t have all that mass around them to keep cool.
Too much or too little water will kill your plants. The idea is to keep the soil moist throughout, but not wet. Many container-grown plants need to be watered once or twice a day when it is hot.
Use a watering can or garden hose to wet the soil directly (not just the leaves!). If you still can’t tell how much water is needed, consider a digital moisture meter for an exact reading.
If you plan to be away from home for several days a drip irrigation system can keep your plants happy. Purchase one or make your own (Learn how to make your own pop bottle irrigation system here).
You can also retain water longer by adding “agro-polymers” (sold under the name Soil Moist) to the soil or potting mix before you plant.
Adding organic mulch to the top of your containers will retain moisture on warm days and add nutrients to the soil (remember that nutrients leach out each time you water and need to be replaced.)
Most plants need 7-12 hours of sunlight a day (especially herbs and vegetables with fruits). If you don’t have that, look for shade tolerating varieties like spinach and chard.
Read seed packets to determine the amount of light an individual species needs. Here’s what the packet terms mean:
Full Sun: Between 6 and 8 hours of direct sunlight per day.
Partial Sun: Plants require between 4 and 6 hours of sunlight a day, preferably in the morning and early afternoon.
Shade: Less than 4 hours of direct sunlight per day, with filtered sunlight during the rest of the day.
When you move your containers indoors for the winter, you may need to give them an extra sunlight-boost with plant grow lights. These specially designed lights simulate the sun and help plants thrive through the dark of winter.
Plants grow best at temperatures between 55 and 75° F. Without the insulating earth around them, the roots of container plants get hotter and colder more quickly than their in-ground counterparts.
Move containers inside before it frosts. Provide shade (consider grouping pots together to shade each other) when it gets too hot. Some folks “plant” their containers part way in the ground for insulation.
Nutrient solutions such as compost teas, worm teas made from worm castings, as well as liquid organic fertilizers, fish emulsion and kelp meal provide needed nitrogen, phosphorous and potassium in addition to micronutrients and organic compounds.
Better than synthetic fertilizers, these organic fertilizers won’t burn your plants and supply the necessary macronutrients as well as many micronutrients, minerals, amino acids and vitamins.
Timing is everything when fertilizing as plant nutrient needs change as the plant grows. Annual plants, for example, benefit most when fertilized with a solution high in nitrogen when they are first planted (for growth and leaf development) and then switched to a low-nitrogen, high-phosphorous solution to encourage blooming.
Since nutrients leach from the soil every time your container plants are watered, it is important to add fertilizer every week or two.
You’ll need to devote some time most days to your containers. Between watering, pruning, dead heading and harvesting your crops, container gardens need your devotion.
When it is time to put your plants in their pots, follow these simple directions.
- Wash your pot or container with warm, soapy water. Rinse well.
- Dampen the potting mix — either in the bag (if you bought it) or in the container you mixed it in.
- Partially fill the container with the prepped potting mix. If your container is large and/or heavy, fill it at the location where it will live. (Do not add pot shards or gravel to the bottom of the container, this will actually decrease drainage.)
- Gently remove the plant from its original container. If it is rootbound, loosen the roots before planting (see Salvaging Rootbound Plants).
- Set the plant in the new pot at the same depth as the old container and 1 to 2 inches below the rim of the pot.
- Add soil to the container and pack it gently around the plant.
- Water thoroughly with kelp extract or a compost tea to help it adjust to its new home.
- Add Spanish moss or mulch to the top to help retain water.
Container plants often suffer less pest attacks because they live in a cleaner and more frequently inspected environment than garden or yard plants. However, that doesn’t make them immune from insects, diseases or other problems.
First off, try to avoid pests.
- Inspect plants before purchasing them to make sure they are healthy. Then gently wash them before planting.
- Use clean potting mix and clean containers.
- Wash your hands and tools, too.
- Make sure you are growing plants in the best conditions.
- Get rid of plants that are already infested and have lost more than half of their leaves.
If, after all that, you still have a pest situation try Integrated Pest Management (IPM).
- Monitor for pests daily when you water. Don’t forget to look on the underside of leaves — it’s a great hideout for hungry bugs or their eggs.
- Figure out what pest you are dealing with. If you aren’t sure ask your local extension service. This way you can choose pest control methods specific to your problem, rather than pouring different chemicals on the plant while trying to figure out what works.
- Decide how much you are willing to deal with. The idea is to control the pest, not eradicate it. Can you live with the edges of a few leaves munched? How about your tomatoes chewed up?
- If you need to take action use safe pest control measures that are least harmful to you, your plants, and the environment.
- Problems with smaller pests such as spider mites, aphids or whiteflies, can be tougher to control and may spread plant diseases. To combat these pests, try products for organic pest control.