Planting annual plants - gardener's secrets

Instantly add greenery and colour to your beds

For instant results, or a quick start for plants that need more time to complete their life cycle than Calgary's climate allows, seedlings are the perfect fit. They can instantly add greenery and colour to your beds. In Calgary, spring frosts can last until late May. For that reason, many area gardeners wait until at least June 1 to plant their seedlings outdoors.


The best time to plant annuals is on evenings or cloudy days when it is cooler outside. If planting on warm, sunny days make sure that annuals are watered immediately. Apply a root start (10-60-10) which stimulates rooting. Individually packaged annuals are easy to remove from their packs for planting. If plants are not individually planted, gently separate one plant from another, keeping as much of the root ball together as possible. In either case plant the root ball just below the soil line. If annuals are planted in peat pots, plant the peat pot below the soil line to prevent the pot and the root system from drying out due to air exposure. Be sure to leave adequate room for annuals to develop.

Placement & Planting Tips

Place plants according to sun/shade tolerance. Also consider growing conditions, such as downspouts, and shady spots.

Plant slightly deeper than pot level, usually about 1cm. Cover the old root ball.

Start seeds indoors according to the seeding dates on pages 11 & 12 of this book. Beginning gardeners might want to try the Jiffy Professional Greenhouse.

Seeds for annuals can be planted outdoors as soon as the ground can be worked. McKenzie Seeds offers a huge variety of quality seeds.

Watering Tips

Water slowly and deeply, soaking the root ball regularly depending on conditions. More water is required when the temperature is warmer.

Feeding Tips

Aerate the soil with the mineral Zeolite, which helps to promote the slower release of nutrients and also helps to break up clay.

Feed annuals with regularity using a good quality fertilizer. A good choice is Nurseryland Power Bloom.

Maintenance Tips

Deadhead flowering annuals to extend the flowering season. Deadheading is removing spent flowers to encourage re-blooming.

Steps for planting seedlings

  • Plan area to be planted.

  • Work and condition soil.

  • Dig a hole that will accommodate the seedling you wish to plant.

  • Remove seedling from its flat or pot. Massage root ball gently. Plants that have roots that are crowded in their pots will benefit because the roots will sometimes continue to grow around in a circle, never reaching out for moisture or nutrients.

  • Set plant in hole and add soil until the seedling is planted at the same level as it was in its container.

  • Firm down soil around the seedling and water in well.

  • Fertilize the plant with transplant fertilizer typically a higher middle number fertilizer like 10-52-10, 10-60-10 or Myke to help prevent transplant shock.


Note: Peat pots should always be removed since they do not degrade well in Calgary's short summer and often dry climate.

Hardening Off

Seedlings grown indoors or in a greenhouse will need to be hardened off. Hardening off is the process of adapting a seedling grown indoors to the outdoors over the course of a couple of weeks. Differences in temperature and light intensity may set back plants and delay flowering if the plants are not gradually acclimated to both. To start, plants should be kept in a sheltered area away from intense sun and harsh winds. A cold frame is an excellent place to harden off your seedlings but any sheltered spot will work well. Plants should be covered or brought inside at night if temperature or wind conditions dictate. Over the course of two weeks, gradually increase the plants' exposure to the sun intensity and other elements. At this point, seedlings can be planted outside in beds or rows whenever weather will permit.

If you purchased your annuals at greengate, it's quite possible they have been hardening off in our open roof greenhouse. If you are unsure, check with our staff. Some annuals do not stay here long enough to be completely hardened off.


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