Get planting: the best bulbs for window boxes, beneath a tree and mixed borders

As all good gardeners know late September marks the beginning of the spring-flowering bulb planting season. Pop these fleshy, modified stems in the ground this autumn and you’ll be casting a kind of horticultural spell that will magic up a world of beauty, a form of horticultural alchemy that never ceases to amaze.

But which bulb where? What varieties, for example, are suitable for a window box, or for beneath the shade of tree or shrub? Which will do well in a large pot or in a mixed border? What about mixing different varieties together in the same container or in the ground? Are there any that need a little cosseting or which will grow happily with minimal intervention?

And what about longevity… are all of them properly perennial or are some best discarded after they’ve finished flowering? See below for some useful suggestions.

For a window box: Treat these containers like gardens in miniature, using species/varieties of bulbs that reflect their compact size and scale. Examples include varieties of snowdrops, scilla, chionodoxa, crocus, hyacinths, anemone (varieties of Anemone blanda and Anemone nemorosa), grape hyacinths (Muscari) and compact varieties of daffodils (examples include Narcissus ‘Tete a Tete’, Narcissus ‘Martinette’ and Narcissus ‘Niveth’), as well as dainty reticulate irises (Iris reticulata) and small tulips such as Tulipa saxatilis.

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For a decent display plant the bulbs very generously and much more densely than you would if planting in the ground (so almost touching) and use a really good quality multipurpose compost leavened with plenty of horticultural grit or vermiculite for good drainage. For maximum impact limit your choice to no more than three-four different species/varieties, and plant them in layers, with the earliest flowering varieties to the top and the latest flowering to the bottom. Then finish off with some hardy, low-growing bedding plants such as violas, pansies or forget-me-nots, planted tightly together to cover the compost, bearing in mind that the latter’s growth will be minimal in the cold, short winter days to come.

For beneath the shade of a tree or shrub: Not many species of spring-flowering bulbs thrive in the dry, dense, year-round shade cast by evergreen species of trees and shrubs, but it’s a different story when it comes to the more gentle, seasonal shade cast by deciduous species which suits most of them far better. Even then they’ll appreciate a helping hand in the shape of some well-rotted home-made garden compost or leaf mould worked into the soil at planting time.

Suitable species include dainty snowdrops (the native Galanthus nivalis in particular will quickly form substantial clumps, while the stately Galanthus ‘S Arnott’ is always a great choice); crocus (suitable examples include Crocus tommasinianus, and the giant-flowered Crocus ‘Pickwick’; anemones (varieties of Anemone blanda and Anemone nemorosa); golden winter aconites (Eranthis hyemalis), cyclamen (Cyclamen coum); erythronium; snake’s head fritillary (Fritillaria meleagris) and bluebells (seek out bulbs of the native Hyacinthoides non-scripta), all of which are hardy perennials that when left undisturbed will self-seed and naturalise over time to slowly form gentle drifts.

For a sunny or lightly shaded, spring-flowering meadow, or uncut areas of lawn: As long as you can give their bulbs a moist but free-draining soil many kinds of daffodils (examples include Narcissus poeticus var recurvus, Narcissus pseudonarcissus and Narcissus obvallaris), as well as camassia (examples include the blue-flowered Camassia leichtlinii subsp. suksdorfii, deep blue Camassia ‘Orion’ and the white flowered Camassia leichtlinii subsp. suksdorfii ‘Alba’}; late spring-flowering alliums (Allium siculum and Allium hollandicum) and snake’s head fritillary (Fritillaria meleagris), will all do well in these kinds of growing conditions and are large enough to make an impact from afar.

So will certain varieties of tulip including the scarlet-flowered T. ‘Red Shine’, Tulipa sprengeri, and the red-and-yellow T. ‘Cornuta’ (often sold as Tulipa acuminata). Just make sure to plant their bulbs in naturalistic drifts rather than stiff clumps, avoid deadheading the faded blooms after flowering (you want them to set seed) and delay mowing, strimming or scything until the foliage has died back naturally. This way the bulbs can draw down valuable nutrients from the leaves which allows them to properly fatten underground in preparation for the following year.

For a large container: A large pot or tub gives gardeners the opportunity to splurge on some really choice varieties of spring-flowering bulbs without breaking the bank. Container growing is also the best solution if you’re short on growing space or your garden can’t provide the right kind of growing conditions in the ground (it might be too wet, for example, or the soil too poor), or if you’re dealing with destructive, persistent soil diseases such as the dreaded tulip fire.

Use the lasagne method of planting as described above where you plant in layers, making sure that the lowest layer (the first layer of bulbs into the pot but the last to flower) contains one or two tall, late-flowering varieties. Examples include parrot and double-late tulips such as the eternally fashionable T. ‘Belle Epoque’ or the exquisite apricot-pink Tulipa ‘Ridgedale, or for a really large container some crown imperial fritillaries (Fritillaria imperialis). Famed for their statuesque, slightly punk-rock beauty, the latter produces large clusters of tall-stemmed bell-shaped flowers in shades of yellow and deep orange and capped with a sculptural crown of tufted leaves.

Just make sure to handle their large, fleshy, scaled bulbs very gently and plant them slightly on their sides to help prevent them succumbing to winter rot in wet soil. A handful of horticultural grit added into the planting hole will also help to provide the sharp drainage that this species needs to flourish. For extra oomph, combine your late-flowering layer of taller bulbous species with another late flowering but lower-growing bulbous species such as grape hyacinths (Muscari) that will provide the perfect foil, and then finish off with some spring bedding.

Always bear in mind that even in the midst of winter containers can still dry out during a dry, windy spell of weather, so check them regularly and keep them sufficiently watered when required.

In a mixed border: The choice of suitable varieties of spring-flowering bulbs for the border is so huge that it’s truly mind-boggling. Most of the window box varieties mentioned above will work brilliantly along the front edge to give colour, scent and food for early emerging pollinators and can be followed by colourful, taller drifts of tulips, alliums and crown imperial fritillaries where space allows for successional waves of flowers throughout the spring months.

Just bear in mind the fact that the fleshy bulbs of all of these species can be all too easily accidentally damaged by digging or weeding a border in early spring, autumn or winter, injuring their nascent flowers or even killing the plants by unknowingly slicing their bulbs in half with the tip of a sharp spade. To help avoid this happening, as well as to extend the lifetime of bulbous plants, bury them deeply (as much as 15cm when it comes to tulips) and mark their position with a discreet label.

It’s also important to bear in mind that the foliage of spring-flowering bulbs can look unsightly as it naturally dies back after flowering. Plan for this by positioning them in such a way that the freshly-emerging foliage of nearby herbaceous perennials, grasses and ferns (examples include varieties of cranesbill/geranium, hellebore, pulmonaria, matteuccia, euphorbia) and spring bedding plants (forget-me-nots, wallflowers, honesty) will quickly conceal it. Last but not least for maximum impact avoid a jumble of colour and instead concentrate on larger quantities of fewer varieties, almost always the very best way to make any planting scheme sing.

This week in the garden

The weather extremes, early autumn mists, and record rainfall of recent weeks have been challenging and caused a spike in common plant diseases. This is especially true of plants growing in polytunnels and glasshouses, where the increased humidity and abrupt changes of temperature have been very stressful for some species. To keep plants as healthy and vigorous as possible keep these covered spaces well ventilated during the day, and regularly inspect crops for any early signs of damage, decay or disease. Quickly cut off and bag afflicted leaves, flowers and fruit where possible to avoid it spreading.

Order/buy spring-flowering bulbs in the coming weeks while stocks are still high and there’s still an abundant choice of the most desirable varieties. Recommended Irish suppliers include mrmiddleton.com and connectingtonature.ie. Almost all spring-flowering bulbs are best planted as soon as possible, the exception being tulips, planting of which should be delayed until late autumn/early winter when the ground is colder to help prevent disease. For the same reason only plant firm, plump, healthy looking bulbs that are free of obvious blemishes or pitting.

Dates for your diary

Tuesday, September 26th, (7pm), White Sands Hotel, Portmarnock, Co Dublin, D13 W7X2, an illustrated talk by the renowned American plantsman, nurseryman and author Dan Hinkley on behalf of Howth & Sutton Horticultural Society. This ticketed event (€15) must be reserved/booked in advance, see hshs.ie

Dan Hinkley will also be one of the guest speakers at Kells Bay Gardens’ Southern Symposium (Friday, September 29th – Sunday, September 30th), along with Seamus O’Brien, Bleddyn and Sue Wynne-Jones, Jack Aldridge and Ken Cox. To reserve tickets for this three-day event, see kellsgardens.ie

Continuing until October 1st, the Walled Garden, Mutton Ln, Tibradden, Dublin, D16 R972, Mount Venus Nursery’s annual autumn sale with a wide range of exceptional garden plants for sale at reduced prices, see mountvenusnursery.com