When to Plant Iris Bulbs in Texas?

Written by

William Golder


Dorian Goodwin

when to plant iris bulbs in texas

Iris bulbs are a resilient and low-maintenance species ideal for novice gardeners. As Texas’ hardiness zones span from 6 to 9, which coincides with iris bulbs, the residents here can rely on these plants to add an array of colors to their gardens.

When to plant iris bulbs in Texas? The best time to plant iris bulbs in the Lone Star State is in early fall, around September and October. However, since Texas is such a large state, you’d have to calculate the schedule for growing iris based on your hardiness zone and frost dates.

Read on to find out “is it too late to grow iris bulbs”.

What Month to Plant Iris Bulbs in Texas

1. Based on hardiness zones


Generally speaking, the ideal time to plant iris bulbs is 6 to 8 weeks before the first frost arrives, usually from October to November in Texas. This means the ideal planting schedule is around September to October, although some regions can start as early as late August.

This timespan is necessary for root establishment, which is an essential preparation for the upcoming freezes. Otherwise, the plants may get frost heave and/or die. Planting the bulbs too far from winter is not ideal either, as they may bloom too soon, resulting in a weak plant that can die from frost exposure later on.

In addition, during these months, the temperatures don’t dip below 40°F, which is the minimum threshold for iris bulbs to thrive. It’s also cool enough to ensure that night temperatures don’t go above 50°F or higher, stunting the plants’ growth.

Even if you’re planting iris bulbs in pots, Texas iris growers’ schedule should start within September, as you can bring these plants outside and expose them to light frost for proper growth. By following this timetable, transplanting iris can commence in late July to August.

As the frost dates vary from one hardiness zone to another, you should refer to the table below for a more precise estimation of an ideal planting season.

Hardiness zone First frost date Suggested planting date
Zone 6 October 17-31 August 22 – September 19
Zone 7 October 29-November 15 September 3 – October 4
Zone 8 November 7-28 September 12 – October 17
Zone 9 November 25-December 13 September 30 – November 1
Source: aggie-hort.tamu.edu

2. Based on iris types

The growth cycle of every iris bulb is not the same. For example, Dwarf iris is more suitable for early planting. Bearded iris, on the other hand, can be planted late, as it needs to undergo a period of cool weather to properly establish its roots.

Tips for Successful Iris Bulb Planting in Texas

1. Choose the right iris type

Some iris varieties which grow well in Texas are:

  • Bearded iris
  • Siberian Iris
  • Japanese Iris
  • Dutch iris
  • Crested Iris
  • Spuria Iris

2. Water the plant 1 inch per week


Iris bulbs need 1 inch of water per week. Once the plant is established, irrigate it when the upper 3 inches of soil dries out.

3. Mulch up to 2 inches

Iris bulbs need up to 2 inches of mulch made from organic matter, which should be spread around the plant but not in direct contact with the crown.

4. Use slow-release fertilizer


Slow-release fertilizer (NPK ratio of 10-10-10) is a good option for iris bulbs. It leads to uniform plant growth and provides nutrients for up to 8 weeks or longer.

5. Prune it in a timely fashion

Early winter is a good period for pruning. It involves eliminating the foliage except 6 inches above the ground to aid root development and reblooming iris.

6. Protect against pests

The best ways to protect iris bulbs against pests are:

  • Dig a wire mesh 6 inches into the soil to prevent critters, rodents, and pests from damaging the plant.
  • Mix some sharp gravel near the perimeter area to discourage rodent movement.


When to plant iris bulbs in Texas? After reading my article, you certainly have come up with the perfect planting schedule for these colorful flowers. By following this guide, you can expect your handy work to bloom from March to May.

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