Summer Flowering Information
Bulbs that bloom in summer, rather than spring, are usually not as winter hardy as spring-flowering bulbs and cannot survive the winter outdoors on the Prairies. This group includes dahlias, gladioli, begonias, some lilies, and numerous small bulbs. They are often started in pots indoors, in March or April, and planted outdoors after the last spring frost. In fall they are dug up, cleaned, allowed to dry, dusted with Bulb Dust, and stored in a cardboard box or paper bag (not plastic) containing vermiculite, sawdust, or peatmoss in a cold but frost-free place until next spring. The inexpensive smaller bulbs can be treated the same way but are usually replaced every year as their size makes them hard to find once planted and the cost is minimal.
Gladiolus
For top quality blooms, select high crowned corms at least 1 ½” in diameter. They will produce a single sturdy stalk with large flowers. Wide, flat corms with hollow centres are older, and not as vigorous. In Calgary, corms started in the house about the end of April will have an earlier flowering season then those planted directly outside. They can be planted several to a large shallow pot (ice cream pails with holes punched in the bottom, or large bulb pans work well) in a mixture of 2/3 potting mix and 1/3 sand, just burying the corm. Keep slightly moist, and in a bright light once growth begins. Placing outdoors when weather permits can harden them off. Bringing in or protecting if there is danger of frost, and planted outdoors about the beginning of June. They should be planted slightly deeper outdoors than they were in pots. If preferred, corms can be planted directly into outdoor beds about the end of May.
Gladiolus like a sunny spot, sheltered from wind. They are planted about six inches apart. Fertilize with an all purpose fertilizer (15-30-15) monthly. They will bloom in late July and August, in a wide array of colors.
In fall, after a frost, dig up corms, and cut tops several inches above the top of the corm. Keep in a warm, dry area for about two weeks, until the tops are dry. Pull off the old corms, tops and roots, dust with bulb dust (to prevent any problems with insects or disease) and store in a frost-free cold, dry place in vermiculite or peat moss in a cardboard or paper container. The little “cormels” on the corms can be stored separately and planted next year – they take about three years to bloom.
Thrips are a problem with gladiolas. They are tiny insects, which leave long white streaks on leaves and distort blooms. Dusting with bulb dust before storage and again before planting is essential. Planting in a different area the next season is helpful if practical
Tuberous Begonias
Start tubers indoors at the end of March. Plant the bulbs in a shallow tray or pot in any well-drained planting medium, i.e. Golden Acre Professional Mix. Set the tubers in this mix, with the depression upward about an inch apart, do not cover tuber with soil. Set the tray in an area where it will have at least 60 F temperature to break dormancy. Keep rooting medium slightly damp. Bright light is necessary, but keep out of full sun and keep water out of tuber’s depression (the hole in the centre of the tuber).
As soon as the tubers are well rooted and shoots are ½” or more long, transplant into individual 6” pots. Use the same planting medium as stated above. Fill pots without disturbing roots. Do not cover the tuber with planting medium.
Keep the planted tubers in a warm area in bright light but shaded from the hot sun. Too much heat will produce long, weak growth. Feed weekly with a flowering fertilizer diluted at half strength, such as Plant-Prod 15-30-15 or Plant-Prod 20-20-20. They are both excellent fertilizers. Plant the tubers outside after the threat of frost has passed, where they will be sheltered from wind and hot sun. Tubers can be removed from pots and placed in open soil, about 12” apart. You can leave them in their pots and plunge them into the flowerbed. This is sometimes preferable in case of early frost – it is easier to take them indoors.
TIP: Stake tall plants or those heavy with blooms.
In the fall, after a light frost, reduce watering until the leaves die. Dig up, break stem close to tuber and allow them to dry in an airy location. Dust tubers with bulb dust to prevent insect and disease damage and store in dry peat, perlite or vermiculite. Store in a cold frost-free room
Dahlias
Similar care to a begonia. Mature plants can range from a few inches high to several feet, so choose appropriate size for that area where they are to be planted. They are usually started in the house about the end of April, to be set outside after any danger of frost is past. Dahlias are planted so that the long fingers are spread out pointing down, with the top of the root just below soil level, in a sunny spot sheltered from the wind.
The larger types will need staking. If a stake is set in at planting time it will avoid possible root damage which could occur if you tried to insert a stake into the ground later.
Fall care is the same as for tuberous begonias.
