When to Plant Gladiolus

Can you give me some tips on planting gladiolus? When’s the best time, and when do they bloom? And should I order them online or buy locally? -Beverly

The best time to plant gladioli (Gladiolus sp.) is in spring. Most varieties of gladiolus are hardy to zone 7 and can be left in the ground over the winter in those zones. In areas colder than zone 7, they should be planted in spring after your last frost date, and they’ll need to be dug up in the fall and stored with your other tender bulbs.

Technically a corm, not a bulb, gladiolus are considered tender, which means they do not require a period of cold in order to bloom (unlike bulbs, like daffodils, which must be chilled in order to bloom). They can be planted in the spring around your last frost date.

Gladioli bloom about 90 days (three months) after they sprout in spring, so the bloom time really depends on when you plant them. In warm climates, where they stay in the ground year-round, gladioli bloom anytime from late spring (deep South) to midsummer (middle South). In cooler climates you can expect blooms about three months after planting. Do successive plantings two weeks apart until June for a nonstop summer show!

As for where to buy gladioli, it’s up to you, but your local garden center may have only a limited selection, particularly if they only sell packaged bulb mixes. Ordering will give you access to the hundreds of unique varieties of gladiolus, but shipping delays may put you late in the planting season.

Either way, make sure your gladiolus corms are plump, healthy, and primed to bloom. Gladiolus corms are given a number rating based on their size (#1 is large, #6 is small). Buy no smaller than #3 corms in order to have blooms this year. Or, if you don’t have graded corms to choose from, pick corms larger than 1” in diameter.

Further Information

Julie