How To Plant Flowers In Large Planters

Celebrate color by filling containers to the brim with flowers. Learn how to create gorgeous container gardens.

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Photo By: Julie Martens Forney

Fill Planters With Pretty Annuals

Large planters can bring a porch, patio or driveway to colorful life when you fill them to overflowing with flowering annuals. Start with a planter that’s at least 14 inches across to create a (somewhat) mobile flower garden. This large container features bloomers in bright colors: ‘Tiger Eye’ gloriosa daisy (Rudbeckia), ‘Summer Jewel Red’ Savia coccinea, Profusion Double Fire zinnia and ‘Callie Purple’ calibrachoa.

Make Large Pots Lighter

Keep big container gardens light enough to move by filling the bottom third with lightweight plastics. Upside down flower pots and an empty lidded juice bottle neatly fill space in the bottom of the pot and won’t rot during the course of many growing seasons. Using plastics in the bottom of pots also saves on soil—saving you money. Plastics promote healthy plants by providing an air pocket for plant roots, which helps to prevent waterlogged soil, even during the wettest seasons. Where to find possible space fillers for large planters? Raid your recycling bin, choosing rigid plastics over softer, milk jug-types.

Fill Pots With Soil

Fill container gardens with a commercial planting mix developed for use in pots. This type of potting soil typically contains high levels of organic matter, such as coir (coconut fiber, which helps retain water) or shredded fir bark, along with materials like perlite to increase air pockets near plant roots. Start with a quality potting mix for best results. Fill pots two-thirds full with soil. Add slow-release fertilizer now, mixing it into soil. Use a product with low numbers similar to 4-4-4.

Mix Water Storing Crystals Into Soil

Blend water storing crystals into soil prior to planting. Sometimes called water retention polymers, these crystals absorb water, transforming into a gelatinous material. As soil dries, the gel also dries, releasing water into dry soil. Water storing crystals help reduce the amount of time you spend watering by releasing stored water to thirsty plant roots.

Save Plant Tags

Tuck plant stick tags into soil at the back of the pot. This helps if you need to identify plants during the growing season or fine-tune growing conditions. Take digital snaps of plant tags and the mature container garden design to guide you as you craft future plantings.

Clean Up Annuals Before Planting

Before planting, remove any dead or broken leaves on plants, including any sitting on the soil surface. These leaves can harbor diseases or pests, which you risk transferring to your container garden if they’re not removed. Also pull any weeds present in flower pots before planting.

Slide Plants From Pots

Watering plants or gently squeezing pot sides can make it easier to remove plants from pots. If you see roots like this, it means the plant has been growing in the pot for a long time and has become root bound, with roots growing in the shape of the pot. Tease and loosen roots, using your fingers or a weeding knife, which might be needed in a case like this.

Inspect Plant Roots

This plant shows just a little bit of root circling at the bottom of the root ball. Otherwise, the root system looks strong. Healthy roots are white. Diseased roots are brown or black, and the soil often has a rotten, sewer gas-type odor.

Loosen Plant Roots

Gently loosen any part of the rootball that shows signs of circling roots or roots that are growing on top of each other on the outside of the rootball. There’s no need to loosen the rootball if roots aren’t overly thick and encircling the container. In that case, just plant the seedling.

Tuck Plants Into Soil

In large containers, position largest plants first. Add soil around plants to bury the rootball. Tuck plants into soil to the same depth they were growing in their original pot. As you add soil around a plant, firm it just enough to keep your plant upright. Don’t forcefully push soil down so it’s packed tightly. You want some air pockets around roots in containers.

Water The Planter

Immediately after planting, water your container garden thoroughly. Use a watering can with a rose or the gentle shower setting on a hose end sprayer. You may have to water the pot several times over the course of a few minutes to completely soak soil. If you’re planting in one area and will display container gardens in another, place your pots in their final destination before watering, because wet soil is heavier to carry.

One Month Later

Plants should fill out and be blooming strongly one month after planting. Approximately four to five weeks after planting is the right time to start giving containers a weekly dose of soluble plant food. Or you can wait until midseason and add a handful of slow-release fertilizer to the top of soil and water well. Delay adding a saucer beneath large planters until you need to water the pot daily to keep plants from wilting. Otherwise, you may create root rot if roots have not filled the entire soil volume.

Give Pots A Lift

Use pot feet to elevate large planters. This provides air flow to roots and protects the surface beneath the pot from excessive and continued moisture, which can damage wooden decks and paver joint material. Elevating pots also helps prevent large faded spots on wooden decks that develop beneath pots and plant saucers. Here, small wooden blocks work well as DIY pot feet.

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