How to keep pots and planters blooming all summer (2024)

FARGO — Do you know what the flower said after telling a joke? “I was just pollen your leg.”

We are living in gardening good times. Drive around any neighborhood and up and down city streets and you can’t miss the beautiful flowers blooming in pots, planters, hanging baskets and containers of all sizes.

There are more flower choices to grace containers than any time in history. Plant breeders responded to the popularity of potted annuals by developing ever-increasing numbers of flower cultivars especially suited for containers, blooming profusely on well-branched plants.

Chris Flynn / The Forum

I appreciate the new flower varieties because I remember when they didn’t exist. During the years my wife, Mary, and I operated our garden center, choices were slim in comparison. Now when we visit garden centers for our container plants, we’re kids in a candy store.

Although the choices are outstanding, it’s still up to us to give them the care they need to thrive when we get the plants home and potted. Following are tips to keep container flowers blooming all summer long.

• By mid-June, most flowers in containers are well on their way to rooting and establishing, and they’re producing abundant growth which can be enhanced by fertilizing. Plentiful nutrition encourages more flower buds and better branching.
• Many potting mixes contain beads of slow-release fertilizer which provide a slow and steady stream of nutrition to the plants. As the label on most of these potting mixes indicates, the plants can be additionally fertilized with water-soluble types.
• If you are reusing potting mix from previous years, which works fine, the slow-release fertilizer is usually long gone. When we’ve reused potting mixes, they can be recharged by adding slow-release fertilizer, and the most readily available brand is Osmocote. The label indicates how much to add for each size container. When using slow-release fertilizers, the label usually indicates that plants can also be supplemented with water-soluble fertilizers.
  

  

  Chris Flynn / The Forum

• When using water-soluble fertilizers, such as the popular brand Miracle Gro, plants appreciate being fertilized every week or 10 days. Another option is to fertilize every time you water, using half the strength listed on the package label.
• Watering is critical to flowering container success, and it can be a challenge to keep moisture adequate, especially with types like hanging baskets. Watering frequency depends greatly on the size of the container and the weather. Small pots on hot days might require watering daily. The soil volume of very large, deep containers is more forgiving and rarely needs daily watering. If a fingertip inserted to the first joint detects moisture, the container is probably fine for that day. Keeping containers continually soggy is a recipe for root rot. Hanging baskets, with their increased exposure, might require daily watering, unless the basket is large. If at all possible, prevent flowers in containers from wilting, which damages flower buds, and there’s definitely a wilting point of no return for the entire plant.
• Remove old, “spent” flowers as they whither to prevent seed pods from forming, which drains energy from the plants and can diminish continued flower production. It’s not enough to merely pull off the dried flower petals, the developing seed pod on which the petals were attached needs to be pinched off or cut away. Some newer cultivars of container flowers are “self-cleaning,” which means the old flowers fall away without producing seed pods.
• If by mid-summer container plants are looking scraggly, leggy or past their prime, most can be rejuvenated by trimming back by half or more, which prompts a flush of new growth capable of better bloom.
• Caring for containers while away on vacation can be a challenge, unless you train someone to water the way you’ve been watering. To ease the watering task, even sun-loving containers can be moved to the shade for a week or two, which greatly reduces their watering needs.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at donald.kinzler@ndsu.edu.