Beginner’s Corner: Container Gardening – Part 1, Containers

 by Doug Chyz

Did you come back from your local iris sale with more irises than you have room for in your garden or are you a container gardener already? Are you looking for a temporary home for your irises until you get beds prepared, or would you like to have a few larger containers filled with irises as specimen plantings anchoring walkways or patios? No matter the reason, growing irises in containers is easy. The following are some tips, tricks, and traps for growing irises in containers.

First, you need to consider what the size of your containers will be. You may have locations that allow for very large containers, or you may be restricted by space or even funding. Large decorative containers can be expensive and then you need to add soil to them which is another expense. Speaking from experience, I know that irises can be grown in containers from one gallon in size to very large ones so do not be afraid of using smaller ones especially if you are using them for temporary homes.

A large container makes a great statement

Although I have successfully used one-gallon nursery pots, my preferred size for temporary homes are three-gallon nursery pots. They provide space for the irises to increase and will allow irises to bloom over a two-to-three-year period if you want to keep them in the containers that long. Realize that nursery pots have drain holes and they will need routine watering – read daily during the summer. If you provide a basin under the pots that will hold some water the irises will thank you, but they will still need daily watering during the summer.

You can enjoy irises in containers

I currently live in South Carolina near the coast and do not have to worry much about winter weather. Before moving here, I lived in Virginia with snow, ice, and freezing weather during the winter. My potted irises remained outside all year round. They did fine, but if you live in an even colder climate area you may consider locating the pots in an area where you can mulch around them. You do not have to worry about them being covered with snow; but if you are having a long dry spell during the winter, you should water them. Also, if you had basins under the pots, you should probably remove them for the winter.

Don’t overlook the opportunity to use a large container if you have a place for one or more. I have used them with one variety of iris with several rhizomes to get a nice potted clump effect, and I have used them for several different varieties to include smaller dwarf irises along the outer edges and taller iris or irises in the center. And consider various types: Siberian, Louisiana, or Japanese would make great choices and for those of you who can grow Pacific Coast Natives, larger pots would make great showcases for them.

In Part 2, I will talk about soil for containers, so come back again.

Irises in Containers

by Tom Waters

Irises are not usually thought of as container plants, but they can grow quite well that way, and there are a number of advantages to doing so.

Two Iris pumila cultivars,
'Wild Whispers' (Coleman, 2012) and
'Royal Wonder' (Coleman, 2013),
growing happily in a large container

The irises I choose to grow in containers are mostly dwarf bearded irises and the smaller arils and arilbreds. Tall bearded irises look out of place in even the largest containers, and a light container soil mix may not give them the support they need when top-heavy with bloom. The smaller irises, however, are naturals for container culture. They bring the plants closer to eye level for viewing, and allow them to be moved from place to place for best effect. If attractive containers, like oak barrels or terracotta pots are used, the effect can be quite lovely and dramatic.

There are additional advantages to container culture. I tend to put rare or choice plants into containers when I first acquire them, as it makes them much easier to weed and care for. A small iris that might get lost in an overgrown summer garden and succumb to neglect, is kept safe in a container where it can get the attention it needs.

Two forms of the exotic oncocyclus species Iris paradoxa
in a large container with a gritty soil mix

Arils are another good candidate for container culture in climates where summers are too wet to grow them successfully in the ground. The container can be stored in a warm dry place through the irises' summer dormancy period. It is also possible to provide a coarse, well-draining soil mix that would be difficult to maintain in the open garden.

As a hybridizer working with dwarfs and other small irises, I also appreciate that containers make the blooms more accessible. It's much nicer to pull a chair up to a container than to crawl around on the ground to harvest pollen or make a cross.

Most of my containers are inexpensive plastic models, in the largest size possible (two to three feet in height and diameter). Even the smallest irises enjoy a wide and deep root run. I fill them with various soil mixes, depending on what I have at hand, but I usually use a mix of my garden soil (a somewhat sandy silt) and commercial potting soil, sometimes with addition of compost, coarse sand, or even small gravel. The irises do not seem too picky about the exact composition of the potting mix. I like to use a top dressing of gravel as a mulch. It also looks nice, especially if a few rocks are positioned on top to make a miniature landscape.

Even in a container with enriched soil, irises will not go forever without dividing them and refreshing the soil mix every few years. Keep an eye out for overcrowding or declining vigor. Also, it is important to keep to a regular watering schedule; how frequently you water will depend on your climate, but the only time I have lost an otherwise healthy plant in a container was when I accidentally let it get bone-dry in the summer. Containers are less forgiving in this way than garden soil.

If you've never grown irises in containers, give it a try this year! You may find it offers both esthetic and practical rewards.

Iris reichenbachii blooming profusely in a container

Treasures found while attending Convention in New Zealand

By Maggie Asplet

I have been attending our Conventions here in New Zealand since 2008 and have always taken the opportunity to make sure I either meet new people, or see new things.  Basically, just to have an awesome experience.

2019 did not disappoint.  Although not entirely relating to irises, it is about people with a passion and some of the real treasures you meet in life.

Arriving in Timaru on Friday 15 November with plenty of time prior to the opening of our Convention in the evening, Kerry (member from our Gisborne group and first time attendee) and I set off walking to find a supermarket and also find where our venue was for the evening festivities.   Easy part was venue found, only a 5 minutes walk.  

That sorted, we continued in what we thought was the correct direction to find a supermarket.  Starting to doubt ourselves we stopped a nice young man who had just picked up his son from school.  After a short discussion as to where the supermarket was, he asked why we were visiting.

The very proud vege gardener 

And his young son, the budding new gardener

Well, that was the wrong thing to do (for him) as he got an ear full about our addiction and having contracted the iris virus.  From this, we learnt that this nice young man and his son also had a virus - that of growing vegetables.  He said "do you want to come and see my place? It is just around the corner."  We took the opportunity to do this and then spent the next hour in his garden and looking at what you can go on the small 1,000 - 1,200 sq meter section.

All this work is in the hope that he will hold onto his title of being the best vege grower in the South Canterbury area.

As you can see, most of the back yard is covered with garden

As you can see, every space is used - lettuce growing so can be picked just as you want it

It is fair to say that this family has a virus, it maybe different from ours, but you never know because our paths crossed, maybe they will just more interest in our passion.  Oh, and we never did find the supermarket, we decided we didn't have time for that and went back to our lovely motel.

Our second treasure is actually a member of the NZ Iris Society, Michael Midgley.  He made the mistake of sitting at the back of the bus, and any of you who know me, know that is exactly where I like to sit.  So, Kerry and I got to spend two days in conversation with Michael as we traveled around the tour gardens. An absolute wealth of knowledge.

One of Michael's passions is alpine plants and growing them.  At the conclusion of the convention our trusted convention conveyor, Marilyn Rathgen  took a few of us on a 1 1/2 hour drive to his house, across some of the most beautiful country to finally end up at Lake Tekepo, the home of Michael.

Beautiful view of Lake Tekapo

And the view from Michael's house

The convention guest speakers, Gary White and Andi Rivarola were part of this rather special group to experience something just so beautiful.  The knowledge shared, the passion very noticeable and created the desire to go home and try and create a miniature alpine garden.  Still in the process of thought only ... got the tub in place but nothing done to it yet.

The group braving the weather - from left - Kerry Smith (Gisborne) Michael Midgley, Wendy Davies (Gisborne), Andy Rivarola (Frozen), Marilyn Rathgen (our tour guide) and Gary White (busy taking photos) me on the other side of this photo

Alpine Garden and how the rocks are arranged - these rocks are from the area

The plants do have name tags, just buried in the garden

Last view of the alpine garden

That evening was spent sitting around the dinner table sharing a meal, glass of wine, and plenty of talk.  Just brilliant.

I was lucky enough to bring home a couple of little alpine plants that Micheal carefully dug up - some Iris maritima and Iris sintenisii, both of which I am very pleased to say are growing and will be transplanted to my alpine garden.

Michael has registered two irises in the past - Iris 'Merel' a Siberian registered in 2000 and SPEC-X sibtosa, Iris 'tailormade tekapo'.  This was registered in 2014 after having won the Begg Shield (A NZ award) in 2013.

Iris 'Tailormade tekapo'

I would like to encourage anyone that is reading this, if you have not attended an iris convention, then you are missing out.  You just never know what you might come across.  Perhaps you will meet one of our iris treasurers.

Iris ensata, Iris laevigata and Pseudata in Containers

By Chad Harris

Iris ensata and laevigata have been cultivated with container culture for centuries. In Japan several different flower forms and indoor display regulations were specifically formatted for container growing of Iris ensata. You may also find that growing these water lovers and the new hybrid “Pseudata” in containers easier, as you will have better control of the rich moist soils that they demand.

Soils: A good soilless container potting medium should be used. Here at Mt. Pleasant Iris Farm we use ‘Miracle-Grow’ with 6 month feeding. We use it not only for the patio container, but also for the germination of the seed of our breeding lines.

Container: A one gallon container is the minimum, for a single or double fan plant. This will keep the plant for one growing season, requiring yearly transplanting.

One gallon containers need to be transplanted yearly for the health of your plant and container.

I highly recommend that a larger container be used; three to five gallon will be optimum for two to three year growing seasons. Note that the size of containers for starting seed is a one half gallon.

Seedlings in half gallon containers.

The seedlings are grown for one to two years in this size before being transplanted out to the field.

Light: Full sun with a minimum of six hours to bloom properly. Areas with more intense sun and or heat will find that morning sun and afternoon shade will benefit both the plant and the bloom. While the plant wants to be in the sun the root zone needs to be kept cool. With a large collection this can be achieved placing the containers close to each other while shading the outside containers with planks boxing them in. The smaller collection the shading can be achieved by double potting.

Shading the poly container by double potting.

Placing the smaller container into a larger heavier decorative ceramic container, this is the method that we use on our patio. One could also use a very large decorative container that could hold several smaller poly or plastic containers. A clump look with many different varieties can be achieved without mixing them up, losing their names.

Iris ensata in containers.

Water: These plants are water lovers and should not dry out, keep evenly moist. During the summer this may demand a daily watering. A deep tray filled with water will allow the plant to stay completely hydrated for longer periods of time. For larger collections a child’s wading pool could be used, or a box made of planks lined with a pool liner. Drill holes into the sides one to two inches from the bottom for overflow drainage. The rhizome of the plant should be above the waterline, this is critical for Iris ensata especially during the winter months. Iris laevigata can grow with its crown under water with two inches covering; however it is best to start the new plant above the waterline to help prevent rot. You can gradually submerge the plant after new growth appears. Pseudata (being half Iris ensata) I would play it safe and would grow as Iris ensata, with the rhizome above the waterline.

Iris ensata in containers.

Fertilizer: Use a slow release for acid loving plants mixed into the potting mix. Or use a water-soluble and add directly to the water. Do not use Bone Meal in any application as this will change the PH and can kill these acidic loving plants.

Iris  laevigata in patio containers.

Transplanting: Repot right after bloom, discarding the old soil, roots, and rhizome. The new rhizomes are in a full growth mode at this time through the summer and fall until the winter sets in.

First frost: time to cut the foliage back.

Winter Care: After a light freeze, cut all of the foliage off at container level. Mild winter areas (USDA Zone 8-9) containers can remain out in the pools and or above ground. Colder climates the containers should be lifted from the flooding pools or trays and buried in a prepared bed with a good mulch cover. In the spring return the containers to the flooding pool, lightly fertilize after new growth starts to appear.

For the many that have tried to grow these water lovers in their garden and have failed, give container growing a try. It is definitely easier to maintain their demanding cultural needs of a rich moist soil. You may also be able to push the envelope of where they have not been grown before surprising your iris club at your next show. Give one a try.