Peak Interest: June and July
A mesmerizing rainbow of colour, over 960 types of iris bloom at Laking Garden.
The iris collection was RBG’s first herbaceous collection of importance with the plants being planted in 1947 with the main emphasis focusing on tall bearded iris. The name Iris derives from Greek meaning rainbow, referring to the wide variety of flower colors found among the many species and cultivars. Our collection includes award-winning bearded iris and hundreds of others including miniature bearded, dwarf bearded, intermediate bearded, border bearded, tall bearded, Siberian, spuria and wild species iris.
With a number of varieties with differing bloom times, there are iris to see for multiple weeks in early June.
Current status: Finished blooming for the season.
The iris collection was RBG’s first herbaceous collection of importance with the plants being planted in 1947 with the main emphasis focusing on tall bearded iris.
Historic Bearded Iris Bloom Dates
Note: bloom dates can vary drastically from year to year. Check back for our “bloom watch” updates.
|Year||Date of Peak Bloom|
|2022||Week of June 2|
|2021||Week of June 12|
|2020||Week of June 11|
|2019||Week of June 14|
|2018||Week of June 5|
|2017||Week of June 14|
Where to Find Iris at RBG
Royal Botanical Gardens is made up of four distinct formal gardens contained within 1,100 hectares of nature reserve, across the municipalities of Hamilton and Burlington Ontario. See all our garden areas and start planning your visit at rbg.ca/gardensandtrails
1221 Spring Gardens Road, Burlington
The largest collection of iris can be found in RBG’s Laking Garden, alongside the peony collection.
Parking: $3/hr to a maximum of $15. Free with an RBG Member parking pass.
What’s in Bloom?
Blooms are ever-changing in RBG’s five cultivated garden areas and nature sanctuaries. Check back to learn what’s blooming now or see the blooms calendar for a rough estimation of what to expect in a particular season.
About RBG’s Iris Collection
As of bloom time 2021 the collection contains 968 types of iris of which over 600 are of the tall bearded class. The collection also features a mix of both bearded and beardless iris.
Curator in the Collection
Jen and Alex in the Iris collection at RBG’s Laking Garden talking about why people love iris, the best time to see these blooms, and highlighting some of the strange names you’ll see on your next visit! Watch the video to learn more!
Tall bearded iris (TB) form the major part of RBG’s Iris Collection. These plants attain 70cm (27 inches) or more in height and make a stately addition to any garden. They are much loved by iris fanciers and horticulturists as the colour and pattern range is breath taking. The TB collection is designed to interpret and display breeding trends from the 1920s to the present day.
The collection features both heritage and modern cultivars. Acquisition priority is given to those irises that fulfill the following criteria;
- Attainment of specific awards given by the American Iris Society (AIS). This ensures RBG’s collection displays iris with superior flower form, colour, number of flower buds and stems and general growth qualities. Look for the following awards on tall bearded iris labels;
- Honorable Mention (HM) – several are awarded each year to those irises registered with the AIS. An iris becomes eligible for this award in its second year after introduction.
- Award of Merit (AM) – a limited number of iris are eligible for this award two years after receiving an HM.
- J. Wister Medal (JW) – one medal awarded each year to the best tall bearded iris.
- Dykes Medal (DM) – the very highest medal awarded. Only one iris per year receives this medal and is open to any iris from any classification.
- Irises of Ontario introduction.
- Irises of Canadian introduction or with reference to Canada.
- Irises which may not have won AIS awards but are notable due to unusual colour or flower form.
- New introductions in order to display the best of what’s new in the world of tall bearded iris.
Standard dwarf bearded iris (SDB) attain a height of 20-38 cm (8-15 inches). Producing a wide range of unusual flower colours during May and sometimes June, these irises will tolerate shade better than other iris classifications. They grow well and make impact in mixed borders or even rock garden settings.
Intermediate bearded iris (IB) are tall reaching 41-70 cm (16-28 inches) in height. Bloom time occurs between mid -May to mid-June and growth is typically vigorous. These plants may be planted in clumps for a broad splash of colour or as specimen plantings where the individual blooms may be viewed in detail.
Siberian iris (SIB) grow to a height of 60 – 120 cm (23-47 inches) and bloom in shades of blue, purple, red-violet or yellow, with newer cultivars in brown and orange shades. Siberian irises are hardy plants requiring moisture in spring and although they can withstand dry periods in summer and later months, irrigated clumps will develop faster into specimen plants. Being very graceful plants they are a superb addition to perennial borders.
Spuria iris (SPU) are tall, elegant plants that are 60-152 cm (23-59 inches) in height with exotic colour mixes. They are useful plants, flowering up to two weeks after tall bearded iris, and significantly extend iris flowering season.
Species iris – It is thought that the genus Iris contains up to 300 species of which nearly all are distributed in temperate Northern hemisphere zones, particularly Eurasia to Asia and in semi-desert or cold rocky mountainous areas. Species iris may also be found growing along grassy slopes, meadowlands and riverbanks. RBG has a very modest selection of species iris on display.
Iris interpretive bed
To observe the diversity between types of bearded iris the interpretive bed displays 2-3 cultivars of the following bearded iris classes;
- Miniature dwarf bearded iris (MDB)
- Standard dwarf bearded iris (SDB)
- Intermediate bearded iris (IB)
- Miniature tall bearded iris (MTB)
- Border bearded iris (BB)
- Tall bearded iris (TB)
In addition this bed contains some beardless irises to compare and contrast with the above.
The History of RBG’s Iris Collection
Laking Garden (originally known as the Spring Garden) was designed by RBG Curator Matt Broman in 1945. The garden which was to include an iris collection was laid out in 1946 due to a generous donation of tall bearded iris cultivars by Mr. William J. Moffat, a local Hamiltonian school teacher, and Director of the American Iris Society (AIS).
The introduction of the collection was given further impetus by the founding of the Canadian Iris Society (CIS) in September 1946. As a result, RBG received unparalleled access to iris cultivars from all across North America.
By 1948 260 iris cultivars were displayed in the collection comprising donations from the Moffat collection, newer cultivars from breeders in Tennessee and standard older and historical irises from Mr. J.C. Taylor’s collection at the Department of Horticulture, Ontario Agricultural College (now the University of Guelph), Guelph.
The design was laid out to display breeding trends and accomplishments within the tall bearded iris class. The collection remained in the original Broman design until 2005 when it was replanted in a fleur-de-lis style lay out. The design was again rejuvenated in 2013 restoring a more formal design, reminiscent of the original. This was done to support better care and management of the collection and to better tell the story of tall bearded iris breeding trends through the decades.
Iris have long flowering stems with intricately shaped flowers and are described as such;
- The upper three petals are referred to as standards.
- The lower three petals are referred to as falls.
- The three upright structures in the middle of the flower are referred to as style arms.
- The top part of a fall surrounding the beard is referred to as the haft.
- The hair like structure at the top of a fall is referred to as the beard. Some irises do not have such a feature and are termed beardless.
Iris flowers play a prominent part in art and symbolism. Vincent van Gogh painted several pictures of irises and iris features prominently in Philip Hermogenes Calderon’s painting Broken Vows. Louis VII adopted the fleur-de-lis as a symbol in the 12th Century. A red fleur-de-lis is the coat of arms of Florence. Contemporary use of iris imagery can be seen in the Quebec flag.
Caring for Iris
Bearded iris thrive in well-drained soil and are best planted in July, August or September when rhizomes are dormant. This also allows at least six weeks before first frost. Choose a location that receives at least 6 six hours of full sun a day and plant so that the tops of rhizomes are exposed and roots spread out facing downward in the soil. Firm the soil and water in to help settle the soil. Plant rhizomes 30-60cm (12-24 inches) apart. Irrigate to aid establishment but thereafter rely on natural rain only as tall bearded iris don’t require regular watering. Spent blooms should be removed after flowering and remove any diseased brown leaves. Divide and transplant tall bearded iris every 4-5 years before rhizomes become overcrowded. August and September is ideal as rhizomes are dormant. Remove older rhizome growth and replant the newer growth which will produce superior blooms.
The beardless iris in RBG’s collection enjoy a sunny location in order to promote superior blooming. For these classes of iris choose a location that has at least half a day of full sun. Siberian iris enjoy even soil moisture content whilst spuria iris require dry growing conditions during summer dormancy in July and August. The best time to plant is in fall as cooler temperatures encourage root growth and this allows the rhizomes to establish before winter. Increased rain fall at this time of year also helps the plants to settle in. Plant these types of iris about one inch deep in a loamy soil ameliorated with humus or compost. Keep the beardless rhizomes well watered until new growth appears.
Support Horticulture at RBG
The care and growth of our horticultural collections are possible thanks to the generous support of RBG Members and donors. With a donation to Growing up Green, you can ensure an active, vibrant and healthy future for the children of today and tomorrow through our horticultural and conservation projects.
Royal Botanical Gardens (RBG) is the largest botanical garden in Canada, a National Historic Site, and registered charitable organization with a mandate to bring together people, plants and nature.
More to See, Naturally
Other Major Collections
As a botanical garden, Royal Botanical Gardens acquires, collects, researches, exhibits, conserves and interprets a living horticultural collection.
Plants of interest are ever-changing in RBG’s five cultivated garden areas and nature sanctuaries. Check back to learn what’s blooming now or see the blooms calendar for a rough estimation of what to expect each season.
Discover what’s happening in the gardens! Some programs, events, and experiences listed below are included in general admission / membership, while others require separate registration.