Irises are surprisingly easy to grow, but advice online must be modified for the Mojave Desert and southern Nevada. If local weather is hotter, cooler, or wetter than usual, adjust your garden care accordingly (Check the local National Weather Service offices for current and forecast conditions)

Regardless of the time of year, add these to your daily inspection of your garden:

• Remove dead outer leaves.
• Spray for aphids and roly-poly bugs as you find them. Natural pesticides only.
• If leaves turn yellow, fertilize with iron.
• Pull weeds so they don’t compete with the irises for nutrients and water.

January

Spread triple phosphate (like 0-30-0 or higher) fertilizer lightly around irises and carefully scratch it in around the rhizome. Water thoroughly.

February

In the last week of the month, fertilize with a balanced 15-15-15 fertilizer, scratch in if you’re using granules, and water it in. Plant chilled rhizomes when overnight temperatures are consistently 50-60 degrees.

March

Remove dead outer leaves. Spray for aphids as soon as you see them. Look for natural beneficial predators like ladybugs or use natural pesticides or wash well with high pressure water. Start looking for buds.

For more information about home gardening, please get in touch with the Master Gardener Help Desk (702) 257-5556 or  extensionClarkMG@unr.edu (great for sending photos with your questions)

April

If it’s windy, support flower stems with bamboo stakes and guide side stalks. Newly planted rhizomes may not
bloom the first year.

May

Deadhead flowers and cut back fully-bloomed stalks low to the ground. Feed after blooming is done, with
balanced 15-15-15 or 7-7-7 fertilizer. Add compost and mulch but don’t cover the rhizome.

June

Don’t over water. Irises don’t like “wet feet.” Too much moisture can cause root rot.

July

Supplement drip irrigation with hand-watering if needed, depending on summer heat and rain.
Dig and divide through this month (every 3-5 years or when the bed gets crowded or less productive).

August

Prepare new beds and amend soil with compost and mulch in old ones. Continue to groom existing plants for
debris and pests. Adjust watering based on heat and rainfall.

September

Replant divided rhizomes when the temperature stays consistently below 100 degrees.

October

Feed with 15-15-15 or 7-7-7 fertilizer.

November

Apply a slow-release fertilizer.

December

Shared rhizomes can be chilled in the refrigerator if not already planted. Wrap loosely in newspaper.

Fertilizers:

Fertilizer makes up for a lot of the shortcomings of southern Nevada soils. Commercial fertilizers are typically labeled with three numbers, such as 15-15-15. They represent nitrogen, phosphorus, and potassium, abbreviated “NPK”.

Nitrogen (N) stimulates root growth and encourages green leaves. Most forms of nitrogen in fertilizers are water-soluble, so they wash away if you overwater. Too much nitrogen gives fast but unsturdy growth, which can lead to soft leaves that are susceptible to bacteria, insects, and extreme weather.

Phosphorus (P) enables root growth and flowers (and then fruit and seeds). Some forms are insoluble, but in a commercial mix, phosphate compounds overcome this.

Potassium (K). Its superpower is water movement, so it promotes root growth and overall plant hardiness through disease and pest resistance. Since nitrogen, phosphorus, and micronutrients are water-soluble, potassium is crucial to moving those things “all around” any plant.

Choose your fertilizer with the end result in mind.