When to Plant Lilies in Colorado

Lilies (Lilium spp.) are among the most impressive summer-blooming bulbs, delivering bold, upward- or outward-facing trumpet blooms on tall stems from June through August. Asiatic hybrids are the most cold-hardy, earliest to bloom, and easiest to grow; Oriental hybrids bloom later with intensely fragrant, larger flowers. Orienpet (OT) hybrids combine the hardiness of Asiatics with the fragrance and size of Orientals. True lilies (not to be confused with daylilies, which are Hemerocallis) form scaly bulbs that persist and multiply underground, returning reliably each year with increasingly large clumps.

Colorado spans USDA hardiness zones 4b, 5a, 5b, 6a, 6b, 7a (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

Find Your County

Click your county for exact Lilies planting dates based on your local frost dates.

Hover over a county to see details. Click to view planting guide.

Lilies Planting Calendar for Colorado

▸ Zone 4b ~155 day growing season · Full guide →

Last frost: May 1 · First frost: October 3 · 155 day season

Activity	When	Date Range
Transplant Outdoors	May 15	May 15 – May 29
Bloom	August 7	Aug 7 – Oct 9

▸ Zone 5a ~166 day growing season · Full guide →

Last frost: April 25 · First frost: October 8 · 166 day season

Activity	When	Date Range
Transplant Outdoors	May 9	May 9 – May 23
Bloom	July 18	Jul 18 – Oct 10

▸ Zone 5b ~178 day growing season · Full guide →

Last frost: April 18 · First frost: October 13 · 178 day season

Activity	When	Date Range
Transplant Outdoors	May 2	May 2 – May 16
Bloom	July 11	Jul 11 – Oct 10

▸ Zone 6a ~193 day growing season · Full guide →

Last frost: April 10 · First frost: October 20 · 193 day season

Activity	When	Date Range
Transplant Outdoors	April 17	Apr 17 – May 1
Bloom	June 26	Jun 26 – Oct 2

▸ Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

Activity	When	Date Range
Transplant Outdoors	April 10	Apr 10 – Apr 24
Bloom	June 19	Jun 19 – Sep 25

▸ Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity	When	Date Range
Transplant Outdoors	April 1	Apr 1 – Apr 15
Bloom	June 10	Jun 10 – Sep 30

Growing Tips for Colorado

Plant bulbs in fall (preferred, September–October) or spring, setting them 3 times their diameter deep (typically 4–6 inches) with the pointed end up. Lilies need excellent drainage — they will rot in wet or heavy clay soils. Site with full sun on stems and blooms but cool, shaded soil at the base (ground cover or shallow-rooted annuals at their feet is ideal). Remove spent blooms but leave stems and foliage until they yellow naturally, as the bulb needs the foliage to photosynthesize and rebuild energy stores. Red lily beetle is a serious pest in the Northeast and Pacific Northwest; inspect plants regularly and hand-pick adults and larvae. Never plant Oriental or Asiatic lilies near cats — all Lilium species are highly toxic to cats. Year 2+ bulbs produce the most stems and largest blooms.

Lilies in Other States

Frequently Asked Questions

When should I plant Lilies in Colorado?

Planting dates for Lilies in Colorado depend on your USDA zone. Colorado spans zones 4b, 5a, 5b, 6a, 6b, 7a. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Colorado for planting?

Colorado contains USDA hardiness zones 4b, 5a, 5b, 6a, 6b, 7a. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.

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