How To Plant Annual Flowers In Beds
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Our warm Colorado spring season can be deceiving to most gardeners. A 65 degree day in March brings visions of planting a beautiful annual flower bed. However, in reality, that bed would be lost within the week when snow and freezing temperatures would destroy the early planted beauties.
In the Denver metro area, the last frost day is usually May 15th. Most annuals should not be planted until this date. Frost and cold tolerant pansies, violas and ornamental cabbage and kale can be planted as early as the beginning of March if weather permits, and provided that you ‘acclimate’ the plants first (explained below).
Other frost tolerant annuals such as snapdragons, petunias, stock, sweet alyssum, dianthus and primula can be planted at the beginning of April generally with no problems. Watch for a late frost and be ready to protect the plants.
Acclimating: Anytime you transplant greenhouse-grown plants to the “real world” to your garden, remember to always acclimate them, that is, to gradually expose the plants to outside conditions for approximately 5-7 days before planting them outdoors. Place the new plants outside in an area protected from sun, wind, and extremes of heat and cold for a few hours the first day and then bring them back inside. Gradually lengthen the time they are outside until they remain outside full time for at least two days before planting. Don't forget to water them!
Amending the Soil: While the plants are acclimating, you can work the soil and add organics to the area where the plants will be living. We suggest adding ⅓ compost to ⅔ of the native soil. For annuals, only the top 6 inches need be worked since they are shallow rooted. But, the better the top 6 inches is amended, the better blooms and plants you’ll have! If you are adding a granular fertilizer, mix it into the soil now. A good balanced fertilizer for flower gardens is fine.
Planting: For best results, plant them on a cloudy day, or in the early evening when it begins to cool down. Carefully remove the plants from the pot or pack. Spread the roots slightly to gently loosen packed roots. Make a hole large enough to accommodate the root ball. Place the root ball into the hole at a level so the ground soil level is no more or no less than it was in the pot or pack.
Watering: Check for moisture every few days. Soil should feel slightly dry before watering again. Water thoroughly so the water penetrates the soil and reaches the roots. Some plants are more drought tolerant than others and will require less frequent deep watering. Check cultural requirements if unsure.
Fertilizing: We recommend fertilizing annual flowers regularly. Foliar feeding (in a sprayer) gives fast results, but a watering can will work just fine. Granular fertilizers are mixed into the soil and then watered in. These are easy to use, but take a bit longer than water soluble fertilizers to reach the plant. They are still very effective.
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