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Tulips: the flowers that get on with almost everything else in the garden

The beloved tulip is in bloom in all corners of the globe; just watch out for the dreaded tulip fire

Tulip bulbs planted in late autumn/early winter will produce a flush of unique colour the following spring. Photograph: David Ryder/Bloomberg

Fionnuala Fallon's face
Fionnuala Fallon
Sat Apr 20 2024 - 05:00

It’s tulip time, those fleeting weeks of the year when Irish gardens are filled with the graceful, brilliantly colourful flowers of what must be one of the world’s best-loved spring flowering bulbs.

The most companionable of plants, the versatile tulip gets along well with pretty much everything else in the garden. This is why its flowers look equally at home in a traditional country cottage plot or a chic town courtyard, or when used to add grace and seasonality to the most elegant of spring-flowering containers.

Technically speaking, it’s also the easiest of plants to grow. Nature does almost all the hard work for us, by packing enough energy into each fleshy bulb to fuel its cycle of growth so that all it needs is water and light. We just have to pop these plump plants-in-waiting into the ground in late autumn/early winter, and up they’ll come the following spring.

Or at least that was traditionally the case until climate change put a spoke in the wheels, by increasing the risk of the dreaded tulip fire, or Botrytis tulipferae to give it its proper name. Only evident once the plant is in active growth in spring when the leaves and flowers appear blotched, spotted, pocked and distorted as well as prone to rot, this fungal disease has taken hold in many gardens throughout Europe in recent years. Carried there by infected bulbs or sometimes by fungal spores carried on the wind from infected plants, it can remain active in the soil for up to three years to infect any new plantings. Mild wet weather greatly favours its spread (the fungus is active at temperatures between 5 degrees to 27 degrees), one of the reasons why traditional advice is to hold off planting tulips bulbs until late autumn/early winter when the weather is colder. Or at least, when it used to be.

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Tulips in Merrion Square, Dublin. Photograph: Dara MacDónaill

Our renewed lust for this most beautiful of spring flowers is another big part of the problem. Not since the tulipomania of the seventeenth century have gardeners pursued the newest and most covetable varieties with such zeal. For some, it will be the deliciously decadent late-double Belle Epoque, a tulip so popular that stock of its bulbs is generally sold out each year by September.

For others, it’s the charms of the Broken and Breeder tulips, with their delicately streaked, feathered and flared petals, or the glimmering, refined beauty of Ridgedale, or the fiery heat of Abu Hassan. Whatever your fancy, the choice is vast, a factor that’s helped to fuel worldwide demand and enabled the disease to hitch a lift into gardens all over the world.

Dublin Castle gardens. Photograph Nick Bradshaw

The solution? Part of the answer lies in prioritising those varieties that have proven themselves to be reliably perennial (that live at least three to four years, often more) and so don’t have to be replanted every year. In this way, not only can we reduce the risk of our gardens becoming inadvertently infected, but we can simultaneously garden in a way that’s both less labour-intensive and more sustainable. Given the considerable difficulties that sustained wet weather caused last autumn-early winter in terms of getting any bulb planting completed, this approach also neatly dodges one of the many gardening challenges presented by our increasingly erratic climate.

Examples of reliably perennial border varieties include the tangerine-red Ballerina (a lily-type, late-flowering variety); White Triumphator (late-flowering lily type); the scarlet-red Appeldoorn (large flowered, Darwin type); the pale-pink double Angelique (late flowering double); orange-purple Prinses Irene (Triumph type, mid to late season flowering); burgundy-red Jan Reus (Triumph-type); soft pink Van Eijk (Darwin-type). The smaller, species types (examples include T praestans; T tarda; T kaufamannia; T greigii; T turkestanica) are also longer-lived when given suitable growing conditions. For best results, plant bulbs deeply (18cm-20cm) and bear in mind that tulips are best grown in a sunny spot and in free-draining, weed-free soil that’s not overly rich in organic matter and isn’t heavily mulched or fertilised (too much of either increases soft, sappy growth vulnerable to infection).

Prioritising reliably perennial varieties aside, another part of the solution is to plant your tulip bulbs less densely and into less crowded growing conditions. This improves air circulation and lowers humidity, reducing the chances of conditions evolving that are favourable to the development of tulip fire.

A crop rotation cycle similar to that used in kitchen gardens and allotments is also recommended so that at least three years elapse between fresh plantings. Much as we already do in the kitchen garden or allotment, vigilance is also required in terms of keeping a beady eye out for very early signs of the disease, especially in terms of newly purchased bulbs. These should be large, firm and free of obvious bruises, blemishes and mould. Some experts go so far as to advise removing the bulb’s brown leathery outer skin or tunic before planting to inspect its pale flesh for any hidden signs of disease (lesions, black spots or pitting) that it might be concealing. Much like potato blight, quick, thorough and careful disposal of all infected material is advised to slow tulip fire’s spread, including removing any emerging bulbs/shoots showing obvious signs of stunted, deformed growth. All should be immediately removed, bagged and then burned. Good garden hygiene is also important to reduce as much as possible the risk of contaminated soil or plant material being moved from an afflicted part of the garden into an area where new plantings are planned. This includes scrubbing down and sterilising pots and tools before re-use.

In gardens and allotments where tulip fire is already well established and there’s no space to rotate plantings, it’s possible to continue to grow this beautiful spring flower in a limited way in containers and tubs using fresh compost or topsoil sourced externally. But you’ll need to be extra vigilant as regards the risk of healthy plants becoming infected through the spread of contaminated soil or through remnants of older, forgotten but infected plantings emerging in spring. Many gardeners prefer to instead wait out the three-year incubation period and then start afresh with healthy bulbs.

Bear in mind also that there is some limited evidence to suggest that certain kinds of tulips are more vulnerable to the disease than others. The species types in particular seem to be more resilient than the highly-bred border-type varieties.

Almost inevitably, some will see the spread of this destructive, persistent tulip disease as a sort of moral allegory that highlights how we’ve allowed our desire for beauty to override the planet’s natural order. Botanical proof of our hubris. But I’m not convinced. Instead, I see it as just yet more evidence of the cyclical nature of gardening, a dance that’s continued for thousands of years.

This week in the garden

The exceptionally wet spring has delayed many routine garden jobs, causing a bottleneck of chores all calling out to be sorted. If you just don’t have time to properly clear and prep empty beds this coming week, or if the soil is still too wet to dig, then a useful stopgap is to quickly cut back the weeds and then cover the ground with black plastic or sheets of cardboard laid flat and weighed down with some stones. This will prevent further growth and germination of weeds until the opportunity arises to do a proper job.

Slugs and snails are always very active at this time of year, but especially after the sustained wet weather. To prevent extensive damage to young seedlings and emerging perennials, which can happen overnight, it’s important to take adequate precautions (see this week’s Q&A piece).

Dates for your diary

Saturday, April 20th and Sunday, April 21st, Ballintubbert House & Gardens, Stradbally, Co Laois, the inaugural Festival of Gardens and Nature with an extensive range of expert speakers and vendors, see festivalofgardensandnature.com for booking details

Rescheduled as a result of poor ground conditions to April 21st, Fota House and Gardens, Fota, Carrigtwohill, Co Cork, Fota House Annual Plant, Craft & Garden Fair, see fotahouse.com

Thursday, April 25th, Northridge House, St Luke’s Castle Rd., Mahon Cork, T12H9070, An Artist’s Guide to Creating a Beautiful Garden, a talk by the artist and author TJ Maher of Patthana Garden on behalf of Cork Alpine & Hardy Plants Society, see facebook.com/CorkAlpineHardyPlantSociety

April 27th ( 1.30pm - 4.30pm), Cabinteely Community School, Johnstown Road, Cabinteely, Dublin 18, D18 VH73, The Alpine Garden Society’s Annual Show & Plant Sale, with a wide range of beautiful plant exhibits and plant stalls.