The Society receives many gardening questions. This page was created to share answers to some of the Frequently Asked Questions (FAQs). Get your Calgary gardening help here.

Gardening Tips

What is hardening off?

Hardening off is the process of giving your seedlings or greenhouse grown plants time to transition from their controlled environments to the outdoors. Direct sunlight, strong winds, and fluctuating temperatures can stress plants. Plants need time to adjust to direct sunlight, so their leaves do not get scorched. Young plants also need time to adjust to greater temperature swings. The process thickens the cuticles on the leaves enabling them to preserve moisture.

Once outdoor temperatures are appropriate for your plants, harden them off over a period of several days to a week. Start on a warm day. Place the plants outside in full shade (in a sheltered location) and bring them back in for the night. If it is breezy, you may want to only leave them outside for an hour or two (do not try to harden off your plants on a windy day). Over the next couple of days, place them in dappled shade, increasing the amount of sun exposure each day. By the third night, they can be left outside overnight (only leave them outside if the low will be no colder than 5° C). The plants should be ready for planting in their final growing locations after day five.

Does leaving grass clippings on my lawn cause thatch?

Grass roots are the primary cause of thatch, not grass clippings. Thatch is made up of roots, stems, rhizomes and other plant materials. These materials contain large amounts of lignin (fibrous material) and decompose slowly. Grass clippings are about 80-85 per cent water with only small amounts of lignin, and break down rapidly.

To learn more about the practice of leaving clippings on the lawn, also know as grasscycling, read the information sheet from the City on the Society’s Resources page. The City also has lawn care information on their website

How can I attract beneficial insects to the garden?

Encourage biodiversity!  Choose a variety of plants that bloom throughout the season.  Plants of varying heights will attract different types of insects. Many beneficial insects prefer small, simple blooms.

How can I keep hanging baskets looking good all summer?

Soil in hanging baskets will dry out quickly, especially in windy conditions, so keep up with the watering – this is usually once per day and sometimes even more than that.  Make sure you match plant selections with their site.  Fertilize once every two weeks during the growing season with a water soluble fertilizer formulated for flowering plants.  Deadhead spent blooms when necessary.

What can I grow underneath a large conifer?

Large conifers will compete with other plants growing beneath them for sunlight, water, and space.   You need to be able to control these barriers to plant growth.  The simplest, most workable solution is to set up planter boxes/containers and then plant shade-loving species in them. (Watering will have to be done on a regular basis as the plants might not receive sufficient rainfall).  You are at least able to give the plants the soil and nutrition they require, without competition from the trees.

What are some herbaceous perennial selections for shady sites?

Hosta, bleeding heart (Lamprocapnos spectabilis), bugloss (Brunnera spp.), Ligularia, Astilbe, ferns, queen of the prairie (Filipendula rubra), among others. Visit the Perennial Plant of the Year page under Resources for more plant information. Society Members may visit the Society’s Plant Database under the Members Only section of the website.

How can I design my yard to conserve water?

Select water-wise native plants.  Grow less lawn.  Use mulch.  Make sure your soil is healthy. Use compost.  Install a rain barrel.  Water only when needed. Sign up for a Design Your Yard workshop to learn more.

What plants can I overwinter?

Many tender perennials can be overwintered indoors. Plants that are geophytes (plants that propagate from bulbs, corms, tubers, or rhizomes) which we frequently all call bulbs, can be gently cleaned of soil and stored in a cool dark place over the winter. Usually, they are lifted (dug up) after a light frost, their leafy growth is removed, and stems trimmed to about 2 cm. After air drying for a few days, the can stored in dry potting medium in a cardboard box or unsealed bag. The challenge is to keep them dry (to prevent mould growth) but not so dry that they become desiccated. The stored plant should be checked once a month to watch for mould, provide a air circulation, and add a bit of water (if required). In the spring, they can be potted up, or when warm enough, planted outside.

A few of the common plants that can be stored this way are begonias, canna lilies , crocosmia, dahlias, and gladiolus.

How do I overwinter my geraniums?

Pelargoniums, commonly call geraniums, are related to our hardy cranesbill geraniums but are not hardy in Calgary. These plants can be brought inside and overwintered. They can be grown as a houseplant, have cuttings taken for starting new plants that are grown over the winter inside, or stored dry and dormant.


If you’re bringing your pelargonium in to be a houseplant, before the first frost trim the plant back about one third. Let the wound heal. Dig up the plant and clean the soil off the roots. Soak covered in water with a drop of dish or horticultural soap for about an hour or two to remove potential pests. Rinse off the plant, then pot in a clean container with fresh potting medium. Keep the plant isolated from other plants for two weeks. Ideally, the plant would be covered with a plastic bag with a few tiny holes (for air circulation). Check it regularly for pests. The plastic bag will contain the pests if they appear and should prevent their spread to other houseplants. If no pests are found, it can be moved to its winter growing location. Shoot tips may need to be pinched periodically during the winter to promote branching.


Take cuttings from plants growing outside. Cut a 10 cm length of stem from the tip. Remove flower buds. Let it dry overnight. The next day, brush a bit of soft tissue rooting hormone (#1) on the side of the stem. (Rooting hormone is not required, but it does help encourage root growth.) Plant the cutting in a pot with a soilless potting mix and water. Do not overwater or the cutting will rot. Pelargoniums prefer a drier environment.

Dormant Storage

Lift your pelargoniums before the first frost. Gently shake off excess soil. Stack them like cord wood in a cardboard box or hang them to dry. The plant should be stored in a cool dry dark place. They can survive this way due to their thick moist succulent-like stems. Periodically inspect the plants. Remove leaves that dry and fall off. You may need to soak the roots in water (1 to 2 hours each month of storage) if the stems lose any plumpness. The stems should remain thick and firm. If the stems shrivel, discard the plant. In late March, pot up the plant and water thoroughly. Place the potted plant in a sunny window to trigger growth. It may take a few weeks before you see new growth. Trim off any dead stems.

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