Tall, bearded irises like a well-drained soil in full sun all day. The ground should be clean and deeply dug with well-rotted manure incorporated into the lower spit. Spent mushroom compost or good garden compost are best, not peat (pH 7 to 7.5 is best). Most of the iris family are deep-rooted and should be planted about 15" to 18" apart (38 to 45cm) with the rhizome lying at the surface and the roots spread out and sloping down into the soil, ensuring that there is no air pocket underneath the rhizome. The leaves should be trimmed to six to eight inches (15 to 20 cm) and the roots well firmed into the soil. This prevents wind rock while the roots are developing. They should be watered in and not allowed to dry out for the first few weeks, allowing the roots to get started. After that they will only need watering in prolonged dry spells and once or twice after flowering. Leave them exposed to winter frosts and don't cut the green leaves down. You may be reducing the production of next year's flowers. Simply keep them clean and tidy by removing old and brown leaves and tip the leaves that may collect leaf spot, etc. Cut flower stalks down to 4"/10cm after flowering. Do not cover the rhizomes or they will rot in our climate. They should be planted within two weeks of arrival, preferably as soon as possible.
If you have purchased pots, simply fork over the ground and dig a hole in your prepared bed. Knock the plant out of the pot and place it in the hole with the rhizome level with the soil surface. Water it in. If you have bought a plant in flower it should be staked until you wish to cut off the flower stalk - at about 4ins/10cm. Some varieties do not rush into growth after flowering and may remain dormant for some time, even a year or so. The leaves may die back and it can do a fair imitation of having given up the ghost. However, as long as the rhizome is firm and hard it will wake up eventually and start into growth again in the spring, but it is unlikely to flower again for another year. We find that it is not possible to say why this happens. We plant in blocks of 10 or 15 and sometimes find some that go dormant, while the rest are fine. If we leave them they usually catch up, eventually.
If a plant flowers in the first year with a tall stem and many flowers it is worth staking it as the roots may not yet be strong enough to hold it up. It may fall over, or be blown over, and the roots damaged which may make it shy of flowering for a year.
You may find that some plants are smaller than expected. This can occur for two reasons. Firstly, the season may be late and so the plants have not grown so fast or, secondly, the variety may have small rhizomes anyway. In either case, do not worry. The plants will soon catch up and those with smaller rhizomes will still flower as well as the bigger ones. New roots will rapidly appear. Remember to water them in and, if there is a dry spell, again after a week or so.
In the unlikely event that one of our plants fails within two weeks of receipt we will gladly replace it. After that time the problem will be in your garden. We can give no guarantee that a plant will flower in any particular season. We usually find that failing plants are due to:
- Planting the rhizome below ground level
- Planting in shade
- Planting in wet ground
- Cutting off the leaves or covering in winter
- Keeping under glass in the winter - they should be in the open
- Planting with the roots screwed up in an air pocket under the rhizome
Generally, our climate provides too much rain, rather than too little, hence the need for a well-drained soil to reduce the chance of rotting. If you get small pools of water on the surface of the soil then do something to improve surface drainage. Irises come from a harsh environment and do not need top dressing. By adding coarse grit or sand to the soil the drainage is improved and the ground can be regularly tilled to keep down weeds, the main enemy of irises. The weeds use the nutrients, keep the essential sun from the rhizomes and induce disease by reducing air circulation. The same applies to other border plants growing too close to the irises. Give irises plenty of elbow room.
Crowded and ready to lift and divide
After a few years they will become crowded and may flower less prolifically. They should be lifted any time after flowering and before the first frosts of autumn. The rhizome should be broken or cut into sections of new growth ready for replanting, discarding the old parent rhizome, unless you are keen to increase stocks. If you replant the parent rhizome somewhere out of the way it will produce several new plants in a year or two.
Clump lifted and divided
When replanting, these rhizomes will need some help to avoid being blown over so clip the leaves down to about 6ins/15cm as mentioned above.
Trimmed ready for replanting
The roots are spread out in a two or three inch scoop in the earth and then covered over. The rhizome can be lifted and shaken lightly to ensure that the soil gets down between the roots. The surrounding soil should then be firmed in. Ideally you should try to find offshoots that have their own offshoots coming - and plenty of root:
Lots of shoots and plenty of root
You can grow your irises on pots very easily. Although they like it dry, their roots need water - so make sure the pot or tub is big enough, has drainage holes and crocks in the bottom. Fill it with peat-free compost that has plenty of grit mixed in. As with any pot grown plant, water it when it needs it and don't let it dry out - or you'll have some dormant plants to wait for.
Our pot rack with many plants flowering in their pots.
Don't believe old wives' tales that rabbits don't eat irises. We have had to leave some choice varieties out of the catalogue this year, thanks to our furry friends. Also, due to the good root system moles burrow under the irises to get the worms that live among the roots.
Breeding for fun (strictly amateur)
If you want to dabble in breeding for yourself, take a look at this picture:
The anther has the pollen which needs to be transferred to the stigma. Choose a still, warm day and pick off an anther with a pair of tweezers and take it to the flower of the seed parent that you want to cross it with and brush it onto the stigma of that plant. You should see the grains of pollen sticking to the stigma.
A less subtle method is to choose your parent plants and, one by one, pick an anther from the pollen parent and lay it on the stigma of the other flower. Do this three times so that you end up with three anthers on three stigmas all in the same flower. With a bit of luck the pollen will mature and do its job.
Cover the flower with a paper bag, label it and, within 6 to 8 weeks, the ovary should be swelling. When it turns silvery, pick it off and dry it. When you split it open there will be many brown seeds within. Sow them on gritty, peat-free compost and cover with about a quarter of an inch of compost. Water them in and place them outside in a sunny position. Seedling leaves should appear in the spring/early summer. Care for them until September when they may be big enough to transplant into the open ground - or a larger pot.
If you're lucky they flower in the next year or two and you then throw them all away because they're rather poor colours/plants. You may, instead, trying crossing them with each other, or back-crossing them with one of the parents. You may be lucky and breed a good one. Contact us and we'll sell it for you.