At this time of year with frequently sunny skies and warm breezes, I am overcome by the desire to plant. However, there is still a chance for frost and the ground is still cold. I satisfy this yen by planting my containers.
The first order of business is to refresh the soil in the pots. It is not necessary to remove all of last years potting mix, except in small containers. Just remove the top 5 or 6 inches and toss it on your garden beds. Loosen up the remaining mix and add new soil-less media. I have been adding compost to the commercial mix and have found it very beneficial. I believe that it holds the moisture better. Some commercial potting mixes include a crystal wetting agent, but the U. of Minn. feels that it may tie up the fertilizer. Other mixes come with time-release fertilizer, although it is an insufficient amount and it is cheaper to add your own fertilizer to a plain media. Be sure to wet your potting mix before you add plants as it is difficult to wet peat based mixtures properly. The easiest way is to pour water right into the bag of mix.
Make sure that your containers have sufficient drainage holes. A 20 gallon pot needs 4 to 6 ¾-inch holes and a 30 gallon pot at least 8 1-inch holes. It is no longer recommended to place stones at the bottom of the pots, although you will need a screen or 'crock' to cover the holes. Use pre-soaked terra-cotta pots for plants that like drier conditions and put moisture loving plants like bacopa, cannas and peace lilies in plastic or ceramic pots. Fill the containers to an inch below the rim so that you have room to water, but not so low that the little plants can't be seen. Once the containers are filled and ready for plants you can pot them up as you find plants that suit your fancy. Never pass up a nursery or hoop house as each one has something unique. You can get ideas from their designed containers and do it yourself. The outlets are full of mature baskets and pots that are nice for Mother's Day, graduation and Memorial Day. Since they are in their prime, they have probably filled the container with roots and have no more room to grow. You may wish to repot these into a larger container with some fresh soil. Another option is, to split them up and put them in several containers or in the ground. If you keep them as is be sure to prune them back to the edge of the pot and fertilize. Petunias often need several haircuts through the season.
Check containers daily with your finger and if the top inch feels dry, water them. Pay special attention to the first few weeks after planting so the root-ball stays moist until the roots spread. It is almost impossible to over-water containers especially if it is hot and windy. Water at the base of the plants and never let them dry out. When plants get too dry their feeder roots die and the plants must waste energy reproducing roots instead of fruit or flowers. Some plants such as annual Geranium and Dracaena prefer it a little dry, so be careful not to over-water them. When the weather is cool and wet and when the containers are in the shade, less watering is required. Reduce evaporation from large pots by covering the soil with mulch. Most containers do better if they are kept out of the mid-day sun, so try to give them some shade with a trellis or umbrella at this time of day. Keep your 'Martha Washington' geraniums out of the afternoon sun!
Since containers need to be watered so often, much of the nutrients are washed out and therefore they need to be fertilized frequently. Get in the habit of fertilizing (water-soluble) at half strength every week or two. Use a fertilizer that is high in the second number (Phosphorus) as a rooting solution because it promotes root growth. A fertilizer that is high in the first number (Nitrogen) is good for growing the foliage. You may wish to use a fertilizer with a high third number (Potash) in mid-July as it encourages fruiting and flowering. You are always safe with a balanced or even numbered fertilizer.
The advantage of container gardening is its versatility. You can enjoy plants in and area where a garden bed is not feasible, such as decks, rooftops, pavement, stairways and balconies. You can try plants that you do not have room for in your gardens or that are not hardy for this area. You can keep color going all season long with annuals and move them to wherever there is a lull in the perennial bed. If they do fade, you can move them to a less noticeable spot or change some of the plants in the pot. You have the ability to try new things, which I like to do each year. This year I will try the Vista 'Bubblegum' petunia that is said to be nicer than the wave petunia.
Although a pot with red geraniums, petunias and a spike is beautiful, you can have fun creating container gardens or gorgeous one-plant pots. Use annuals, perennials, vegetables, herbs, bulbs, grasses, and tropical plants in plain, colorful or imaginative containers. Move them around like throw pillows and vary them throughout spring, summer, and fall and from year to year.
Breitling is a longtime West Fargo resident and avid gardener always in search of new ideas.