9 Simple Tips To Help You Grow Gladiolus Bulbs

You can easily grow this most-popular summer blooming bulb

Doug Green
Dec 20, 2019 · 4 min read

The Gladiolus is one of the four most popular summer flowering bulbs because they are so darned easy to grow and they give such huge blossoms.

They make excellent cut flowers and I’d recommend planting a few just for this purpose because once you have them, you won’t be able to resist snipping “just this one….”

Native to South Africa, the glad is also known as the sword-lily because of its sword-like leaves. But there is very little trace of those originating species in the monster hybrids we all love to grow (and have been growing since 1841).

Image by at Pixabay

Flower Types

The large flowering gladiola can be classed into four groups:

This is the most numerous of the group with literally hundreds of hybrids available for your every colour whim.

The flowers on the butterfly types look like butterflies. Hard to imagine how we’d call them butterfly types if there wasn’t some resemblance.

The flowers are smaller than the Large Flowering types and the flower colour is often very strong and bright.

These all have the yellow flowering species Gladiolus primulinus in their genetic makeup. The upper flower leaf covers the other flower leaves, pistil and stamen acting as a little protective cap. It is difficult to see right inside the flower.

Many of these smaller flowering species are quite delightful in themselves and are marginally hardier than the large flowering types. You’ll most often see Gladiolus colvillei, Gladiolus nanus, and Gladiolus tubergenii or their varieties (they come in a wide range of colours) in retail shops.

Planting Instructions

  • Plant gladiola in the full, hot sun.
  • Plant three to four inches apart.
  • Put them three inches deep.
  • They should grow to three to five feet high depending on the variety.

Bloom Times and Getting Flowers Most of The Summer

There are two techniques to get a longer bloom time.

  • Gladiolus come in early, mid-season and late flowering varieties. Plant some of each for season long bloom.
  • If you don’t get or don’t know the bloom time, simply stagger the planting every two weeks to extend the blooming season from very early spring until late May or very early June.

When To Plant

Start planting when the local farmers plant corn. Or when it is not too cold to put your wrist directly on the soil (If it is too cold for your wrist, it is too cold for your bulb. (A rough rule-of-thumb is first week of May if you don’t have farmers next door.)

Sometimes I’ll recommend more tender parts of your rear-lower-anatomy as soil temperature checking devices. 🙂 But that’s only when I’m feeling cheeky he says.

If you plant some a week early and then a few every week, you can have glads in bloom from July through September.

Which Side Goes Up When Planting

No, it doesn’t matter which side is up. The gladiola bulb will sort it out.

Yes, you’ll read other advice online but…

I used to grow several thousand a year on the farm and I’d plow a furrow with the tractor.

Then walk down the row tossing the bulbs into the bottom of the furrow without worrying about spacing or which side was up.

I’d turn the tractor around and plow the turned soil back into the furrow to cover the bulbs.

Trust me, you don’t have to cosset these bulbs.

Crooked Stems

If your flower stem tends to twist and crook, I’d recommend a slightly deeper planting and then do two things.

  • Ensure it never runs out of water and
  • Hill the early growing stem like a potato.

This keeps the bulb (actually a corm) uniformly moist and cool and reduces stem-crooking dramatically.

Silver Streaking on Flowers

The other problem is thrips. This tiny fly gets inside the flower bud and causes flower streaking. (silvery streaks on the blooms)

Blue sticky cards are great thrip traps and you can regularly spray insecticidal soap to knock back any pests on the developing buds.

Keeping Gladiolus Safely Over The Winter

  • Dig the bulbs just before the first hard frost. Allow to dry thoroughly so the soil is dry on the bulb.
  • Brush off the dried soil and store cool, dry and dark until spring.
  • Store in trays with some distance between bulbs if possible. That way, if one gets moldy it doesn’t spread to the others.
  • Check regularly for mold and discard any badly infected bulbs.

Getting More Glads From Your Own Garden

The small bulblets around the base of the corm when you dig it up in the fall (right before or after a frost) can be stored and replanted the following year.

These will take 2–3 years to flower depending on soil fertility. Treat them exactly as you would a full sized corm.

Amazon has a good range of suppliers and varieties. Simply ensure the ratings for the supplier are what you’d expect.

(Note I get a small affiliate payment when you buy my ebooks or use links on this site.)

Doug Greens Garden

A practical organic gardening resource helping you have a better garden

Doug Green

Written by

Former nurseryman, now writer and curious about what’s over the next hill and how to get there in either my Triumph Spitfire or sailboat.

Doug Greens Garden

A practical organic gardening resource helping you have a better garden

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