I think one of the most beautiful flowers standing stately in the garden or arranged in a vase on the table has to be the colourful gladiolus. Gladioli come in standard and miniature sizes. Most of the standard sizes produce one long flower spike after about eight to ten leaves whereas the miniature types can produce many stems of much smaller size. The beauty of this flower is its prolonged bloom time as the buds open one after the other from the bottom to the top of the stem.
I usually try to start my glads some time around the first of April in flats in the greenhouse as this gives a somewhat earlier bloom. However the corms can be directly planted after the soil warms up around the middle of May in our area.
My neighbour, Karen Baer, who always grows the most beautiful glads I have ever seen, shared her method of soaking the corms in 1/4Cup of Lysol to a quart of water for a few hours before planting to get rid of thrips that sometimes arrive with the corms. My latest order of corms came with the instructions to “dip them in a mild bleach solution to kill thrips and bulb mites”.
Glads like well-drained soil with lots of well-rotted manure, compost, bone meal and other humus-rich materials. A pH of 6.0 to 6.5 is ideal for gladioli. They are best planted in a 4-5” (10-12cm) deep trench about 6” (15cm) apart. The rows should be about 2’ (60cm) apart. This will give enough soil to “hill” around the plants as they grow because they are prone to fall over with their top-heavy blooms. Wire supports or stakes can be used in high-wind areas. If you have a sandy or well-drained soil, adding mulch around the end of June will help to retain the much-needed moisture for good growth.
Flowering will usually occur between 60 and 100 days after planting depending on the varieties you have purchased.
The main pests to attack gladioli are aphids and thrips. Aphids can usually be washed off with a stiff spray from the garden hose. Thrips are tiny white or brown insects that suck the juice from flowers and leaves and can do a lot of damage if found in large numbers. Dipping the bulbs when you get them in the spring and after you dig and cure them in the fall can best control them.
The best time to cut the flowers is when one to five buds are open. By cutting the stem close to the top leaf, you allow the leaves to produce more food for the corm to get it through the winter and produce again next year. Glads seem to keep better as cut flowers if you dip them in a 10% sugar solution with a few drops of bleach and leave them in it at room temperature overnight.
Glads are not hearty for our area and must be dug before the corms are touched by frost. The tops should be cut to 3” (7,5cm) and the corms spread out in a well-ventilated place for three weeks. The tops and the old corm should be removed and once again the new corms dipped to kill off any eggs or pests that may be trying to over-winter too. After dipping, dry well again and store in a cool (40F –5C) dry place for the winter.