Growing Gorgeous Irises in Pots: A Guide to Container Planting

Walter Moores grows and hybridizes irises at his Moores’ Enid Lake Iris Gardens near Enid, Mississippi. Some of the iris plants he has introduced are LEMON CHESS ’96, which won two Exhibition Certificates (1994 and 1995) and an Honorable Mention in 1998. The dramatically colored ASCII ART is a recently registered hybridization of Walter Moores which was introduced in 1997.

Another iris some may be familiar with is his TB intro CONFEDERATE ROYALTY. This article previously appeared in the TB Iris Society’s “Tall Talk Newsletter”. Some benefit may be derived from potting iris even in our more northerly Canadian climate.

I wrote an article for the AIS Bulletin about ten years ago that talked about how to start bearded irises in pots. Also, in the last year, I discussed the process with the Iris-L chat group on the Internet. In the spring of 1998, Bob Stroham of Louisville, KY, wrote an article about clay pot culture as a follow-up.

Irises have always been potted to get them off to a good start with growth, but the methods used have changed over the years. What follows is my experience with potting irises for over twenty years.

Why do planting iris bulbs in the pot?

Bob is right when he says, “It’s over 90 degrees, the ground is too dry and hard to dig, and we’re leaving for a vacation tomorrow anyway.” That being said, if you live in the hot and muggy South or Southwest and bought a $45 introduction, you should really think twice about putting that plant out in the hot sun. The alternative is to pot incoming rhizomes and to place the pots in a shady location.

The irises’ root systems that grew while they were in pots will allow them to stay where they were planted. Potting does reduce losses during these two susceptible seasons. If you want your first-year plants to bloom, pot them up and get them established early. This will make sure they do. There are many good reasons to pot irises, but the main ones seem to be to help them grow and bloom.

If you live in a hot area, September is the best month to plant or transplant irises because the cooler weather makes being outside more bearable. However, it can be hard to find a store that still sells rhizomes that are blooming size. Additionally, I have found that when I order early and ask for late delivery, I receive lower quality rhizomes.

I’ve also had cancellations or replacements when I placed an order in early spring and asked for delivery in late August or September. Usually, September is the driest month in the South. Newly planted rhizomes can make the water bill go up because they need so much water. So, to ensure you get quality plants of desired varieties, order early and pot the rhizomes. The boost the rhizomes get while in pots will almost guarantee first year bloom in your garden.

How do I grow potted irises

When a box Iris rhizomes arrives, open it immediately and check the rhizomes for mold or rot. If you find any, trim it off. Also, cut or shave off all roots. Then prepare a mixture of one part liquid bleach to nine or ten parts water. Soak the rhizomes for at least thirty minutes. Allow the plants to air dry before planting.

The clorox bath is needed to kill any rot that might have started during shipping and to keep it from starting while the irises are in their pots. Plants don’t have to be in the ground right away, but if you want them to get a head start, plant the rhizomes within a day or two of getting them.

Irises had been sold at auctions or sales for years, and I had always seen a few in black plastic pots. When I first began potting irises, I used gallon pots because I thought the plants needed at least that much soil to live. I did not trim the roots, nor did I provide a bleach bath.

I used garden soil most of the time. When the pots dried out, it got as hard as a brick. It was hard to move the heavy pots to the spot where they would bloom and to dig a hole big enough for a gallon pot’s worth of plants. I have found that four-inch plastic pots work perfectly for the potting process after trying them out. I have not found a rhizome too large to fit in one. If the toe of a rhizome has an extra piece of growth called a “snout,” cut it off. Think of it as a second rhizome and plant it in the same pot as the mother rhizome.

The potting mixture should neither be friable or compact. One-third of the mix should be Magic Earth (a potting soil with fertilizer), one-third should be garden soil, and one-third should be sand. No other fertilizer is necessary.

Here are several recommendations on how to plant Irises in pots:

• Fill four-inch pots with plant mix all the way to the top, then soak them in water.
• The soil may settle and more may be needed.
• Place the rhizome half-way into the soil without roots and press it down with your fingers.
• Make sure the soil is at the top of the pot so water doesn’t sit in it.
• Putting a rhizome in such a small pot would be nearly impossible if the roots were still whole.
• It won’t take long for new roots to grow and wrap around the soil in the pot.
• Tag or label the plant as usual.

Watering the plants may become necessary depending on the weather. It is best to water the pots from the bottom up. Fill a galvanized tub with three inches of water, then put the pots inside. Allow the water to be absorbed through the drainage holes. Remove the pots when the soil is damp.

It is important to move the pots occasionally so roots don’t find anchor through the drainage holes. A few weed seeds may sprout, but these are easily removed.

Plants may be left in the pots until October to be planted where they are to bloom. While you wait, you should get the iris beds or rows ready to welcome the new plants. When it’s time to unpot, a tap with a trowel will loosen the soil and root ball. That same trowel should have been used to dig a hole about four inches deep. For an extra boost, alfalfa pellets or a balanced fertilizer might be added to the planting hole. Firm the soil around the plant and water.

In summary, many people would consider potting irises to be double trouble. When you compare how fast the irises in pots can grow and bloom to the irises that are planted in the ground, the answer is no. Losses are almost nonexistent.

Planting Iris In Pots | Container Gardening

FAQ

Can iris survive winter in pots?

What are the best irises for pots?

Do iris do well in containers?

What to do with irises in pots after flowering?

Can irises grow in a pot?

Though not traditionally considered to be a container plant, irises can grow well in a pot, provided it is large enough. Bigger pots are ideal, as many irises quickly establish robust root systems. Growing iris in a container will require special attention to the needs of the plant, specifically sunlight and watering.

When should I plant irises in pots?

The best time of year to plant iris in pots depends on the type of roots your plant has. Bulbous types bloom from late February until June in most growing zones. These irises require a period of chilling before blooming and need to be planted anytime from late September to November.

How do you plant irises in pots?

Here are several recommendations on how to plant Irises in pots: Place soil mixture in four inch pots up to the rim and soak with water. The soil may settle and more may be needed. Set the rootless rhizome half exposed in the soil and firm it with your fingers. Make sure the soil level is at the top of the pot so no water can stand in the pot.

Can I plant tall iris in a container?

Container iris plants also require a well-draining potting mix, as the plants can easily become waterlogged. This will help to reduce the likelihood of other common issues, such as root rot. Planting tall iris in a container is possible, however, making sure to properly secure or stake the plant.