Container Gardening Guide: Growing Plants in Pots
Container gardening opens up the world of growing plants to anyone with a sunny balcony, patio, deck, or windowsill. Nearly any plant that grows in the ground can grow in a container with proper care. Containers offer flexibility to move plants for optimal sun exposure, control soil quality completely, and garden in spaces where in-ground gardening is impossible.
Choosing Containers
Select containers with adequate drainage holes in the bottom to allow excess water to escape. Without drainage holes, water collects at the bottom of the pot, saturating the soil and causing root rot that eventually kills most plants. If you fall in love with a container without drainage holes, use it as a cache pot by planting in a plain nursery pot and setting it inside the decorative container.
Container size determines what you can grow and how much maintenance the plants need. Small pots under eight inches in diameter dry out quickly and need daily watering in hot weather, but are fine for small plants like herbs and succulents. Medium pots eight to fourteen inches suit most annual flowers, peppers, and bush tomatoes. Large pots over fourteen inches are needed for large plants like tomatoes, roses, and small shrubs.
Material choice affects plant health and maintenance. Unglazed terracotta and ceramic pots are porous and breathe, allowing soil to dry more evenly, but they dry out faster and need more frequent watering. Plastic, fiberglass, and glazed ceramic pots retain moisture longer and need less frequent watering but provide less air exchange to roots. Fabric grow bags provide excellent drainage and root pruning but dry out very quickly.
Potting Soil
Use a high-quality potting mix specifically formulated for containers rather than garden soil. Garden soil compacts in containers, reducing drainage and air space around roots. Potting mix contains a blend of peat moss or coconut coir, perlite or vermiculite, and compost that provides good drainage, aeration, and fertility.
Add slow-release fertilizer to potting mix at planting time to provide steady nutrition throughout the growing season. Container plants need more frequent fertilization than in-ground plants because nutrients leach out of the limited soil volume with each watering. Supplement slow-release fertilizer with water-soluble fertilizer every two to four weeks during the growing season.
Watering Containers
Container plants need more frequent watering than in-ground plants because the limited soil volume dries out faster and cannot hold as much moisture reserves. Check soil moisture daily during warm weather by sticking your finger an inch into the potting mix. If it feels dry at that depth, water thoroughly until water runs from the drainage holes.
Water slowly to allow the potting mix to absorb moisture rather than running down the inside of the pot and out the drainage holes without wetting the root ball. For pots that have become extremely dry and the potting mix has pulled away from the pot sides, submerge the entire pot in a bucket of water for thirty minutes to rehydrate the soil thoroughly.
Fertilizing Containers
Container plants rely entirely on you for nutrients because the limited soil volume cannot supply all their needs for the entire growing season. Begin fertilizing two to four weeks after planting when the initial nutrients in the potting mix are depleted. Use a balanced water-soluble fertilizer diluted according to package directions every two to four weeks.
Signs of nutrient deficiency in container plants include yellowing lower leaves indicating nitrogen deficiency, stunted growth, pale overall color, and reduced flowering or fruiting. Signs of over-fertilization include leaf tip burn, white salt crust on the soil surface, and excessive leafy growth at the expense of flowers.
Specialty Container Systems
Self-watering containers have a built-in water reservoir at the bottom that wicks moisture up to the plant roots through capillary action. These containers reduce watering frequency significantly, making them ideal for gardeners who cannot water daily. The reservoir typically holds several days’ water supply depending on plant size and weather conditions. Self-watering containers are excellent for tomatoes, peppers, and other large plants that need consistent moisture.
Window boxes are long, narrow containers designed to mount on windowsills, railings, or walls. They are perfect for growing herbs, salad greens, strawberries, and trailing flowers in small spaces. Choose window boxes at least eight inches deep and wide for adequate root space. Ensure they are securely fastened and have drainage holes. Line window boxes with coconut fiber or landscape fabric to prevent soil from washing out.
Hanging baskets allow growing plants where floor or ground space is unavailable. Line wire baskets with sphagnum moss or use plastic baskets with built-in reservoirs. Plant trailing varieties that spill over the edges for the most attractive display. Hanging baskets dry out very quickly and need daily watering in warm weather, sometimes twice daily in hot conditions.
Seasonal Care for Containers
In spring, refresh container soil by removing the top inch of old potting mix and replacing it with fresh mix. Add slow-release fertilizer at this time. Clean and inspect pots before replanting, removing any salt deposits that have accumulated on terracotta or ceramic surfaces.
In summer, move containers as needed to follow optimal sun conditions or to protect from extreme heat. Some containers may need afternoon shade during heat waves. Check soil moisture twice daily during hot periods. Grouping containers together creates shade and humidity that reduces water stress.
In fall, move tender container plants indoors before frost. Empty and store decorative containers that cannot overwinter outdoors. Clean pots thoroughly before storage to remove disease organisms and pest eggs.
In winter, protect overwintering containers from freezing and thawing cycles. Wrap terracotta pots in bubble wrap or move them to a sheltered location. Elevate pots on pot feet or bricks to prevent them from sitting in water during winter rains. Reduce watering for dormant plants.
Plants for Containers
Almost any vegetable that grows in the ground can grow in a container with sufficient pot size. Cherry tomatoes, bush tomatoes, peppers, lettuce, kale, chard, bush beans, radishes, carrots, and all herbs are excellent choices for containers. Choose compact or dwarf varieties specifically bred for container growing when available, as these varieties stay smaller and are more productive in confined root space.
Flowers also thrive in containers. Petunias, geraniums, marigolds, zinnias, impatiens, and begonias are classic container annuals that bloom continuously through the season. Combine thriller plants for height like spike or ornamental grass, filler plants for fullness like petunias or geraniums, and spiller plants that cascade over the pot edge like trailing lobelia or ivy.
Frequently Asked Questions
What is the best size pot for growing tomatoes?
Use a pot at least fourteen inches in diameter and five gallons in volume for a single tomato plant. Larger pots up to twenty inches or ten gallons produce even better results by providing more root space and moisture reserves. Dwarf and determinate tomato varieties can grow in smaller ten to twelve-inch pots.
How often should I water container plants in summer?
Small pots may need daily watering during hot summer weather. Medium pots typically need watering every one to two days. Large pots may only need watering every two to three days. Always check soil moisture by touch rather than watering on a fixed schedule, as weather conditions change water needs dramatically.
Why do my container plant leaves turn yellow?
Yellow leaves are most commonly caused by overwatering from pots without drainage holes or from watering too frequently. Check that your pot has drainage holes and that they are not blocked. Allow the soil surface to dry slightly between waterings. Other causes include nutrient deficiency, especially nitrogen, or the plant being root-bound.
Can I reuse potting soil from last year?
Reusing potting soil is possible but not ideal. Old potting mix may be depleted of nutrients, compacted, or harboring disease organisms. Refresh old potting mix by mixing it with at least 50 percent fresh potting mix and adding slow-release fertilizer. Discard potting mix that grew diseased plants or has become hard and water-repellent.
What is the best location for container plants?
Most vegetables and flowering plants need at least six hours of direct sunlight daily. Place sun-loving containers on south or west-facing balconies, patios, or deck areas. For shade-loving plants, north or east-facing locations with morning sun and afternoon shade work best. One advantage of containers is the ability to move plants as sun patterns change through the season.
How do I prevent potting soil from washing out of drainage holes?
Place a layer of landscape fabric, coffee filters, or window screen material over the drainage holes before adding potting soil. This allows water to drain freely while keeping soil in the pot. Do not use gravel or pot shards at the bottom of containers, which actually reduces drainage and can create a perched water table that keeps roots too wet.
What are the best container plants for shade?
Impatiens, ferns, begonias, coleus, hostas, and caladiums thrive in shady container locations. For vegetables, lettuce, spinach, kale, and chard tolerate partial shade with three to four hours of sunlight. Herbs like mint, parsley, and chives also grow in partial shade.
How do I keep container plants from blowing over in wind?
Choose heavy containers like terracotta, ceramic, or concrete for windy locations. Place a layer of gravel or stones at the bottom of large pots to lower the center of gravity. Group containers together so they support each other. Move lightweight plastic containers to sheltered locations during windy periods.
Can I grow fruit trees in containers?
Yes, dwarf fruit trees grow well in large containers. Choose self-pollinating varieties when possible. Use at least a fifteen to twenty-gallon pot. Provide regular water and fertilizer during the growing season. Move containers to a protected location in winter in cold climates. Citrus trees are excellent container candidates.
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