Fragrance is one of most powerful triggers that can bring back gardens

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When we finally get a few minutes to relax and enjoy the colour and beauty of our summer plantings, particularly those on our patios, often one important ingredient — fragrance — is missing. It’s one of the most powerful triggers that can bring back memories of other times in other gardens.

Fragrance adds so much value to all our plantings, but it can be difficult to find in just one plant, especially when you want a longer blooming period. It’s more a process of incorporating scents from a number of different plants. Most plants produce perfume only while in bloom, and once that phase is over, another plant is needed to continue the sequence of fragrance. On the West Coast, this can be a year-round endeavour.

Temperature affects the intensity of floral perfumes. In very cool or very hot situations, the fragrance will not be as intense. Temperatures between 15 and 25 C seem to be the optimum range for producing significant fragrance.

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As we quickly approach summer, now is a good time to select plants from various families to provide fragrance over the next four months. Annuals are the No. 1 choice, and the beautiful blue and purple heliotropes lead the way with a fragrance similar to baby powder. Not all varieties, however, produce that wonderful perfume. It’s most prominent in the old original, not-specifically-named variety that tends to grow much taller and more vigorously. Its sprawling nature makes it ideal for large containers and even hanging baskets. There is also a white flowering variety that is seldom seen in today’s garden stores. Heliotrope comes in many habit forms, but most of the newer varieties, like H. Marine and Proven Winners Scentsation, are quite compact.

Many annuals, like stocks, alyssum and nemesia, have a nice scent but don’t perform well in the heat. Heat-loving petunias, like the deep blues, have a slight perfume, and Proven Winners Supertunia Priscilla, a double lavender, has a soft, sweet fragrance.

Sweet peas, of course, provide some of the best-known, and most-loved fragrance. Because they’re a legume, they prefer morning sun and protection from afternoon heat. Remember to keep cutting stems, otherwise they will go to seed.

Nicotiana is a great summer annual, and the Perfume Mix variety, with its wide range of colours, has a soft, subtle scent. Nicotiana sylvestris, a tall white variety, can be hard to find, but it has the best perfume of all nicotianas.

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Although alyssum doesn’t like intense summer heat, Proven Winners lobularia Snow Princess is far more tolerant of the sun and has that sweet scent associated with alyssums. It’s a pollinator favourite.

Most summer perfume comes from a few key flowering shrubs. The top performers are the many new varieties of compact buddleias — many of which are now sterile to prevent any invasiveness. Proven Winners Lo & Behold series is very compact (two to three feet) and comes in a range of blues, whites and pinks. Proven Winners Miss series is also a more compact variety (four to five feet) and sports the vibrant reds and violets we all know. My favourites are the Proven Winners Pugster group that are very compact (24-inches tall and wide) and have huge, plump blooms. They all have a long blooming period, high perfume value and are magnets for pollinators and butterflies. The real show-off buddleias are the new lavender Grand Cascade and Pink Cascade. Growing about six-feet tall and wide and producing enormous panicles of blooms (12 to 14 inches long and four inches across at the top), they’re something else.

Daphnes are noted for their strong perfume, but only D. Eternal Fragrance will bloom through the summer. A compact evergreen that flowers non-stop right into autumn, it’s hardy to Zone 5. At the moment, this variety can be a little hard to find due to a supply-and-demand issue, but later this summer, it should be readily available in most garden stores.

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Mexican orange blossom (Choisya ternata), a Zone 7 plant, usually flowers out by early summer, but its enticing perfume in late spring makes it a worthwhile keeper.

Summersweet (Clethra alnifolia), rated Zone 4, is one of the most underused plants in our summer landscape. Most varieties are compact (three to four feet) with glossy, green foliage and masses of spiky, perfumed and white flowers. Clethra Ruby Spice has fragrant reddish-pink flowers.

Sweetspire (Itea virginica) is another seldom-used, perfumed, summer flowering shrub that also has gorgeous fall colours. Proven Winners I. Scentlandia is one of the most highly scented varieties, as is Little Henry. Both do well in containers and are summer ‘must-haves’.

Vining honeysuckles are famous for their long, repeat-flowering habit, but they need lots of sun and good air circulation to keep their foliage clean of mildew. I find the soft yellow variety, Lonicera periclymenum Halliana, to be one of the most reliable performers.

Several jasmine varieties bloom in summer, but most are rated Zones 7 and 8 or higher. Jasminum officinale (Zone 7), a fragrant white, is one of the hardiest and has a long-blooming habit. Many folks use these tender plants on patios simply for their summer flowers and their perfume. Jasminum polyanthum and J. stephanense are some of the most popular.

Of course, nothing beats the perfume of fragrant roses. It’s important, however, to understand that not all roses are scented. So, you must be selective. Roses do best when planted in the ground, rather than in a container. I’m a big fan of Kordes’s highly perfumed varieties, and I really appreciate their great disease tolerance. I particularly love their pink Beverly and their red Grande Amore.

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There are lots of fragrant plants in the perennial world, but very few are long summer performers. Certain varieties of lavender are the exception. While the angustifolias, or so-called English lavenders, with their amazing perfume, are in bloom now, it’s the stoechas varieties that bloom all summer. The new introduction, L. Primavera, is the longest-blooming and strongest lavender to date.

You may not find all these plants in garden stores just yet as many are being planted now for later summer sales. However, do watch for them because the beauty and perfume they will add to your summer garden is often the finishing touch you will love.