Blooming Brilliance: Your Guide to Growing Stunning Bearded Irises

How to grow bearded Irises

Growing bearded irises (Iris germanica) can be a very rewarding experience, as they are well known for their striking flowers and ease of care. They are very drought resistant and tolerant so make a good choice for most gardens. At this time of year they are at their very best in our garden, so it seemed a great time to share our growing tips so that you can grow stunning irises.

Here are detailed steps on how to successfully buy, plant, grow and maintain bearded irises:

Buying Iris

The best time of year to buy an Iris is May and June as you can see them in flower and be confident that you are buying whjat it says on the label. We jave learnt the hard way that when not in flower all `bearded iris look very much the same, and its very easy for them to become mislabelled. Look for well pot grown examples with multiple healthy looking rhizomes with ideally four of five leafy stems plus at least one flower spike, arising from a multy branching rhizome. Avoid sickly looking rhizomes or weak growth which could mean the Rhizome is diseased , old or has only just been potted up as these will be hyarder to establish. Most nurseries and garden centres only carry a very limited selection of Iris. There are literally hundreds of historic and heirloom varieties that are incredibly rewarding to grow and very beautiful to grow. A great source of unusual Iris plants are open gardens in old houses with established Iris beds which often have unusual varieties and specialist Iris nurseries. Our favourite Iris nursery is Seagate Iris Nursery in Long Sutton Lincolnshire near Sutton Bridge. We are hoping to visit again soon so will make a video. You can order bare rooted bearded iris plants from the 1st of August but if you are local, it is well worth visiting in May or June.

Choosing a Location

1. Sunlight: Bearded irises thrive in full sun. Ensure they receive at least 6-8 hours of direct sunlight daily. They also flower better if they have sun shining on their rhizomes. This means they prefer to be in a dedicated iris border if you have the space in your garden, rather than hidden away in a mixed herbaceous perrenial border. You can grow them in a mixed border , but we have found that they tend to produce a lot of leaf this way and not so much flower.
2. Soil: They prefer well-drained soil. Irises do not do well in waterlogged conditions as their rhizomes can rot. Although having said this last year we dug and planted a new iris border in the garden, not realising that it would be waterlogged for most of this spring (its been a particularly wet one in Norfolk and in fact in the whole of the UK this year) and they have survived and in fact thrived despite the rhizomes being submerged under water for several months in March and April. If you soil is very heavy clay it is worth adding some grit or gravel to the soil as well as some organic matter to improve the drainage, or siting them elsewhere. When planting them we tend to site them in areas where the soil is poor and then add some organic matter and top dress with gravel. 

Buying & Planting Iris's

1. Timing: The best time to plant bearded irises is spring if they are pot grown or summer to early autumn (June to September after they have flowered) to allow the rhizomes to establish before winter. Although having said that we frequently buy them when they are in flower in garden centres, so that you can see what you are buying. It's very hard for any gardener, including us, to resist a beautiful bearded iris in full flower. Once you have an iris in a particular colour they are very easy to propagate, by splitting the rhizomes once they have finished flowering. 
2. Preparation:
   • Improve the soil with compost if it is heavy clay or too sandy.
   • Ensure good drainage by adding sand or gravel if necessary.
3. Rhizome Preparation:
   • Select healthy rhizomes with firm flesh and multiple fans of leaves.
   • Trim the leaves to about 6 inches in length to reduce water loss.
   • Pot up any left over rhizomes (there are usually lots if you are dividing an established iris bed) up into pots to give away to friends. 

Planting Process

1. Digging the Hole:
   • Dig a shallow hole or trench about 4-6 inches deep and wide enough to spread out the iris rhizome roots.
2. Positioning the Rhizome:
   • Place the rhizome horizontally with the roots spread out below.
   • Ensure the top of the rhizome is just at or slightly above the soil surface. This is important as the Rhizomes need to be exposed to the sun for the plants to flower well. If you bury them too deeply you tends to get lots of leafy growth but not so much flower.
3. Covering:
   • Cover the roots and rhizome lightly with soil, leaving the top exposed to prevent rot.
4. Spacing:
   • Space the rhizomes 12-24 inches apart to give them room to grow and prevent overcrowding. They grow very fast. 

Watering

• Water the newly planted irises thoroughly.
• Keep the soil moist but not waterlogged until they are established (usually a few weeks).
• Once established, irises are drought-tolerant and only need occasional watering. 

Mulching

• Apply a light mulch to help retain moisture and suppress weeds, but keep it away from the rhizomes to prevent rot. We use gravel as a mulch as it contrasts beautifully with the blue green of the iris leaves.

Fertilising

• Apply a balanced fertiliser (10-10-10) in early spring and after blooming.
• Avoid high-nitrogen fertilisers as they promote foliage growth over flowers.

Maintenance

1. Deadheading: Remove the spent Iris flowers to encourage more blooms and prevent seed formation.
2. Dividing:
   • Divide the clumps of Irises every 3-4 years to maintain vigour.
   • Lift the rhizomes with a garden fork, separate them by cutting with a sharp knife, and replant the healthiest pieces. We find it very hard to compost healthy Rhizomes so if we have more than we need we pot them up to give away to friends or plant them in our vegetable garden as a crop so we can harvest cup floweers for the house. They make a great cutting garden plant as they are not widely available as a cut flower. Our favourite Iris to grow for cutting has a huge very dark purple almost black Iris flower and is called Black Swan. 
3. Pest and Disease Control:
   • We have found Iris's to be generally very disease resistant and not to suffer from pests. Keep an eye out for pests like slugs. Because we mulch with gravel and encourage wild birds and wildlife like frogs and toads into the garden, slugs are not a problem for us, as the gravel deters the slugs, and the wildlife eats them.
   • Practise good garden hygiene by removing dead foliage and debris to prevent diseases like bacterial soft rot.

Winter Care

• In colder climates, you may need to apply a light mulch of straw or leaves after the ground freezes to protect the rhizomes. In Norfolk the Iris's are fiully hardy although our winters are usually very mild and short.
• Remove the mulch in early spring to allow new growth.

By following these guidelines, you can enjoy the beauty of bearded irises in your garden for many years. Their striking colours and variety will add a stunning display to any landscape. They are one of our absolute favourite garden plants. We love them so much we have created several dedicated Iris borders for them as they do better when planted in this way, rather than in a mixed herbaceous border.

Watch our Iris videos to for guidance on dividing and planting and for inspiration

Watch our May garden tour at the farm to see our Iris border for some Iris inspiration