They only bloom once....you can't get them to bloom again unless you plant new bulbs.
In some areas you can leave them in the ground all winter...others you will need to dig them in the fall and store in dry sawdust or sand over the winter. I don't know if it's necessary to dig them in Houston.
Linda C

Not too sure about how to grow glads in Texas...If we want to extend the blooming season here we can stagger the planting by planting a few bulbs then waiting a couple(or more) weeks and planting some more and so on. This way they don't all reach maturity and bloom at the same time so that you have an extended display of blooms.
For some reason the different colors of my glads bloom at different times so I don't really have to stagger my planting.

I leave them in the ground in Southeast Louisiana with a couple of inches of mulch. Plant them about an two inch deep hole and cover with about an inch of soil. I am about ten miles south of zone 8 and mine have returned every year. I get into the low twenties every year. They bloom only once and return every year. They need good drainage so that they don't rot and full sun. You could try planting different types and they might not bloom all at once. Related to the glads are crocosmia and montbretia that can stay in the ground, which I have. Also I have the peacock (acidanthera) variety and the hardy glad (old fashioned pink variety - just finished blooming for me while the others don't bloom until June)

In Houston, they can stay in the ground all year.

If you grow species Gladiolus from seed you can greatly extend the bloom period:
X/Y=Bicolor
SPECIES COLOR BLOOM
G. abreviatus Red/Black Wi-Sp
G. alatus Orange/Yellow Sp
G. angustus White-Yellow/Purple-Red Sp
G. aureys Yellow Wi-Sp
G. brevifolius Pink/Yellow Sp
G. caeruleus Pale Blue/Purple Sp
G. cardinalis Crimson/White Su
G. carinatus variable(Red Yellow Pink Blue) Sp
G. carmeneus Deep Pink Su-Au
G. caryophyllaceus Pink-Mauve Sp
G. cunonius Red/Green Sp
G. dalenii Orange/Yellow Sp-Au
G. debilis White/Pink-Red Sp
G. eklonii Variable Su
G. floribundus Pink-Mauve Sp
G. Geardii Pink Su
G. gracilis Blue or Pink Au-Sp
G. griseus Mauve-Gray/Yellow Au-Wi
G. gueinzii Pink-Purple/Red Su
G. hirsutus Pink/Brown Sp
G. holandii Pale Pink/Dark pink Su-Au
G. hyalinus Brown/Cream Wi-Sp
G. imbracatus Purple Su
G. involutus White-Pink/Yellow Sp
G. liliaceus Red(day)Blue(night) Sp
G. longicollis White/Yellow Su
G. maculatus Brown-Purple/Red Au-Wi
G. melliusculus Pink-Red/Orange/Yellow/Purple Sp
G. monticola Pink Su-Au
G. mortonius Pink/Red Su-Au
G. oppositiflorus Pink Su-Au
G. orchidiflorus Green/Brown/Purple Sp
G. papilio Mauve/Purple Sp-Su
G. permeabilis Pink/Yellow Sp
G. quadrangularis Bright Red Sp
G. recurvus Green/Yellow/Pink Wi-Sp
G. rogersii Blue/Mauve/Purple Sp
G. saccatus Bright Red Wi-Sp
G. saundersii Red-Orange/White Su-Au
G. sericeovillosus Pink-Wine Red/Yellow-Green Au
G. splendens Bright Scarlet Sp
G. teretifolius Red-Orange/Yellow Au-Sp
G. trichonemifolius Yellow/Pink-Red Sp
G. tristis Yellow/Brown/Green Sp-Su
G. undulatus Pink/Green Sp-Su
G. varius Pink/Purple Su-Au
G. watermeieri Gray/Purple Wi-Sp

Hyphenated seasons indicate extended blooming season.

Most or all of the above are usually available from Silverhill Seeds in Kenilworth, South Africa

Here is a link that might be useful: Silverhill Seeds

Old House Gardens is another good source. They specialize in antique or rare bulbs. They have a website which gives detailed information about each kind of bulb, planting, etc. including glads.

livetofish, you can extend the flowering time by buying different varieties of gladiolus. Blooming time differs up to 20 days between the varieties.
I also know that there is a new type of gladiolus called Glamini that supposedly blooms almost two weeks earlier than other varieties.

Here is the list of suppliers of gladiolus corms Suppliers.

By selecting from the above species, you can have Gladiolus in bloom 365 days per year outdoors! You will not even approach that with garden hybrids!

MarcR, how ling does it take to grow glads from seed?

Irina

Irina,

Most will flower (eraticly) the second year. A few summer blooming species will flower the first year if you start them indoors in Early Fall under lights. Nearly all will flower the third year.

wow! thanks for all the great info. I will try to post my Liatris pics. They are spectacular.

sorry I meant my glads.

my next question was going to be about the Liatris.

what about care and feeding after bloom if we overwinter them in the ground? my (first ever) glads have flowered and are getting ratty-looking. should i resist the temptation to cut them back?

blooms 365 days a year? Wow! So if I plant glads now, in August, I'd get blooms in 90 days (ish)? I'm also down in Houston area 8b/9a ...