Let me start by making a disclaimer. The location, soil, and climate of your backyard are different than Roberts Backyard, in Grand Coulee, Washington (the Eastern side of the state). Our backyard has sandy soil. We have very seasonal weather, with highs to 100+ degrees and lows to-0. We have low humidity and rainfall is generally no more than 12 inches yearly, with some of that being in the form of snow. This helps all perennial plants survive the cold winter weather. We live in Zone 5.

I am convinced, after years of experience, that organic matter is the very best thing you can do for good iris culture. There are few things as important in garden preparation as adding organic matter to the soil. Yet, many backyard gardeners have gotten away from adding organic matter to the soil and instead have relied on synthetic fertilizers. After many years of growing irises on the same ground, you begin depleting trace minerals and humus, causing iris growth to suffer. This is when a condition called iris decline begins. This iris decline condition is easy to diagnose.

• Slow down of iris growth and increases from year to year.
• Stress from diseases, such as soft-rot and botrytis.

The cure for iris decline is some sort of soil amendment in the form of organic materials, such as manure, compost, or green manure (alfalfa pellets or cover crop with soil rotation). Here, in our backyard, we use old manure. We don't have acres of ground to rotate year after year. Our backyard is probably much like yours. We, like you, want the best soil possible for healthy iris growth.

I am convinced that old cow or horse manure is the secret ingredient which many backyard iris gardeners overlook. Now I did say that word old. Its very important that all manures be aged at least over one winter so all the salts that burn plants can be composted or leach out. The rancher that I get my manure from saves manure in 50 yard piles. These large piles of manure sit for many years.. Cows and horses walk on them to find high ground and use them for wind breaks. Mr. Rancher always has more manure than he wants (or talks about) and he is willing to give it away for free. Getting it to your backyard and spreading it around will cost you. My back hurts just thinking about it. I'm thankful I have a thirteen year old son that has his own shovel with his own name on it!

Benefits of adding manure to your soil:

• Improved soil structure for better aeration and temperatures, providing a softer soil for easier weed control.
• Support of living soil-organisms such as fungi, bacteria, molds, insects, predatory nematodes and earth worms, keeping the soil alive.
• Improving the ability of all soil to hold the proper amount of water and nutrients during stress of the growing season.
• Maintaining a steady supply of plant nutrients necessary for healthy plant growth.
• Vibrant iris flower coloring.

How much old manure should you use? Here at Roberts Backyard we use a minimum 110 lbs. for every 25 square feet. You may say to yourself, "that's a lot". "Yes, it is!" But, we want the finest soil possible to grow the finest iris and iris seedlings.

What about all the weeds? Yea, you'll have the healthiest growing weeds in the neighborhood and also the healthiest irises. But, really, weeding is always a part of gardening. The improvements to the soil and health of the iris far outweigh a few extra weeds. Besides, I don't think there are that many weed seeds in manure. Its just that weeds grow better.

We hope that this has encouraged you to use some sort of organic soil amendment in your backyard to help you achieve a healthier, colorful, iris bloom.

Merle & Linda Roberts