Gladiolus

Growing gladiolus in the garden

Glad- 'Atom"

Gladiolus are the birth flower of August.  Fifty years ago most gardeners grew glads because they were excellent cut flowers and provided color in the summer garden.   Every farmers market had people selling large bouquets of colorful glads.  I remember walking the aisles of the farmers market in Pontiac and buying large bunches of glads to take home to arrange.  Glads are still grown in mass quantities for the floral trade and used in professional arrangements but the average gardener has all but forgotten the gladiolus and that’s a shame.

Glads have the reputation of being a formal flower, and as such don’t seem to fit into the relaxed, more naturalistic gardens of today.  But there are many varieties of glads and one doesn’t have to be a wizard to weave some of them into today’s gardens with charming results.  With a huge range of colors and flower styles, glads offer everyone some of the most gorgeous flowers around for the summer garden.

Varieties of gladiolus

There are hundreds of varieties of glads.  Choose those whose color interests you or whose size or hardiness are right for you.  That said, here are some glad varieties that might interest you.  “Black Beauty” is a dark, red-black glad that pairs well with “Sophie” a pure white glad.  “Nori” is close to true blue with a white center.  “Yellowstone” is pure clear yellow.  “Princess Margaret Rose” is yellow with rose edges,  “Coral Lace” is coral pink with ruffled edges, “Green Star” is lime green, “Jester” is yellow with a red throat, “Vista” is shades of lavender and white.

Heritage varieties of glads allow you to grow something beautiful and keep a variety alive and thriving.  “Firedance” is small flowered but is a lovely peach with orange shading.  “Starface” is orange and yellow with a red star marking on the lower petals. “Lucky Star” is a rare fragrant glad that is white with shadings of red and yellow in the throat.  “Lilac and Chartreuse” is those colors delightfully combined.   “Atom” is a small flowered red glad with each petal outlined in silver.  “Boone” is a cheerful small flowered yellow flushed with red.  The older smaller flowered glads are easy to blend into perennial beds. 

Hardy forms of glads are sometimes called nanus gladiolus.  They are generally white with colored throats and are small flowered.  “Charming Beauty” is a soft pink nanus glad.  Acidanthera are a close relative of gladiolus with narrower leaves.  The flowers are similar to nanus glads, generally white or pastel pink with darker throats, although other colors exist, and they are fragrant. 
Glad- 'Starface'

Corm concerns

Glads are usually sold as corms, which are a bulb like structure covered with a papery brown husk.  The color of the glad flower sometimes appears as a faint tint on the inner, firm area of the corm color but you can’t rely on corm color to tell you the flower color. At best it can give you a hint of which glad is which if you mix up your varieties.

Corms are sold in the spring for spring and summer planting.  The size varies a bit between varieties, with the corms of miniature and small flowered glads being smaller on average than other glads.  Glad corms are graded by size and generally top size corms are 1¼ inch or larger across.  Smaller corms will produce flower spikes that are a bit smaller but can be economical.  Cormels are baby corms that are often attached to the mother corm when you dig them in the fall.  These tiny corms can sometimes be purchased very cheaply but they may not bloom the first year they are planted.

You can buy corms in packages in stores but these have often been subjected to warm storage conditions that promote early sprouting, rotting and mold.  You can purchase a wider range of glads that have generally been handled and stored in better conditions from catalogs or on line.   When choosing packaged glads look for firm, plump, non-moldy corms with no sprout or only a tiny sprout showing.  Avoid soft, shriveled, moldy corms and those which have long yellowish sprouts.

If you are the economical person who intends to save your glad bulbs each year you should know that the original corm will lose vigor and may not bloom well after the third season.  That’s fine because each year when you dig your glad corms for storage you should find new cormels on the bottom of the parent corm.  These will have the exact type of flower as the parent corm.  Save these and plant them and your glad varieties should last a long time.

Gladiolus have long narrow, sword like leaves.  The size of the plants can vary from about 12 inches high to about 3 foot with the flower spikes making them even higher.  One flower spike is usually produced from each corm.  The flowers all face one direction on the spike and begin opening from the bottom and progress upward. Glad flowers are from an inch across to sometimes 3 or more inches across.  They come in every color from white to the darkest red-black and every mixture of color.  There are some glads with frilly, ruffled petal edges and some with doubled petals.  Depending on the variety glads bloom from 65-100 days after the corm is planted with good growing conditions.

Plant your corms in a sunny spot, glads prefer sandy or sandy loam soils but will do all right in heavier soils that are well drained.   Plant corms about 3 inches deep with the scar or flat side of the corn down.  Glads should not be planted outside until all danger of frost has passed.  If you are in a short season area or want early blooms you can start them inside in pots a month before the last expected frost.   You may want to plant several batches of glads two weeks apart to prolong the blooming period. 

Most people who want glads for cutting plant them in rows about 4-6 inches apart in the garden.  If you are blending them into a perennial border plant them in groups of 3-5 bulbs and make sure they won’t be covered by expanding foliage of other plants as they grow.  In windy areas you may find the taller glads will need staking or the support of a fence.  

Mix a good slow release fertilizer into the soil as you plant the glad corms.  Glads require good consistent watering to flower well.  If it doesn’t rain they need an inch of water or more, depending on soil drainage per week. Mulching plants after they are 2-3 inches tall is a good idea.  If you don’t cut the flower spike for a bouquet cut it off after it finishes blooming.  Allow the leaves to yellow and die naturally before digging the corms or removing the foliage. 

Glads do produce seed if you leave the faded blooms.  You can save the seed and plant it in the spring.  It will take at least 2 years to get a bloom from the seed grown glad.
Glad 'Bibi'

Storing corms over winter

Most varieties of glads are not hardy above zone 7 although there are some varieties that are hardy to at least zone 6.  That means that if you want to save the glad corms you’ll need to dig them before the ground freezes and store them inside.  (But you don’t have to take this step if it’s too much trouble, glad corms are inexpensive and you can buy more the next year.)  If you are in zones 7 or higher simply mulch the ground over the corms with 5-6 inches of mulch before winter.  Most glads will survive the winter and return to bloom again this way.  Treat the glads sold as semi-hardy for those in zone 5-6 the same way.


For those in zone 6 and lower dig the bulbs after the leaves have yellowed or before a hard freeze.  Cut the tops off to about an inch above the corm.  Let the soil dry and brush it off the corms.  Remove any old shriveled looking corms and keep the plump new ones.  Store the dry clean bulbs in net bags or paper bags, not plastic.  You can also store them in containers of dry wood shavings.   The crisper of the refrigerator will do fine for storage, otherwise find a cool place to keep them between 35-45 degrees F.

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