Is your garden fragrant enough? Gardeners often focus on color and design in their beds, borders, and yards and forget to factor in fragrance. Yet scent is keenly important to humans, as it is capable of triggering powerful reactions in the human brain. Information about scent not only travels to the brain for identification, but also travels to the limbic system, the brain's emotion and memory bank. That's why the smell of a flower—say, the lily of the valley that your grandmother used to grow—can evoke a sudden rush of memories.

Scent is relatively easy to weave into a garden, and there are as many options as there are plants. In this month's edition of Smart Gardener: a dozen plants in all shapes and sizes to get your scent palette primed.

Snowdrops (Galanthus)

Blooms in March

Famous as harbingers of spring, but did you know that they're deeply fragrant, too? Because few pollinators are active as early as snowdrops bloom, the flowers power up with a heady, honey fragrance that is irresistible to the first emergent insects. As your garden starts to bloom this spring, mark the places where mini drifts of snowdrops could squeeze in—then order the bulbs and install them this fall. 

Hyacinths 

Blooms in April/May

Although they bloom for just a short time in spring, they're worth that narrow window for their outstanding, head-turning scents. Even a small patch of Dutch hyacinths like Hyacinthus orientalis 'Delft Blue' can scent an entire yard—not to mention beg photos with its spire of true-blue blossoms. Look for them this spring in the front beds of the English Walled Garden; plant bulbs in fall.

Daffodils

Blooms April/May

Plagued by deer? Daffodils are the bulbs for you. Jonquil is a type of daffodil that offers up fragrance and also repels deer. Narcissus 'Baby Moon' is one of the most fragrant of all daffodils; petite and cheery, with soft yellow color, it's tucked into the terraced beds of the Farwell Landscape Garden's Rock Garden. Mark your calendar for this year's Fall Bulb Festival—it's a great opportunity to pick up fragrant daffodils and other bulbs. Plant them in clusters of five or seven in fall.

Old Garden Roses 

Blooms late spring/early summer.

While the Krasberg Rose Garden draws hundreds of visitors daily in May and June, it's at the back of the garden, beyond the fountain and behind the arbor, that you'll find the strong and classic scents of tea (Rosa 'Souvenir de la Malmaison'), damask rose (R. 'La Ville de Bruxelles'), and spice (R. 'Charles de Mills'). These are the "old garden roses," also called antiques or heirlooms. Because many of them bloom just once per year, antique roses are often bypassed for modern hybrids that bloom all season long (frequently at the expense of fragrance). But if you seek out a nursery or website that specializes in old garden roses and tuck a couple into your landscape, you'll be rewarded with both intoxicating scent and inquisitive neighbors.

Hostas

Blooms late spring through summer

Even the most taken-for-granted plants can pack a powerful scent. Take hostas. You may already have them in your yard, but have you noticed whether their flowers are fragrant or not? We admit to a weak spot for those that are, especially in summer. Look for 'Honeybells' and 'Sweet Susan' in the Sensory Garden (one of the best locations for fragrance on the grounds), a fine patch of fragrant 'Royal Standard' just beyond the Arch Bridge on Evening Island, and the variegated foliage of 'Fragrant Bouquet' and bright green, crinkly 'Guacamole' lining the walk outside of McGinley Pavilion.

Lavender

Blooms through summer

The lavender evaluation at the Plant Evaluation Garden wraps up in spring 2016, as Plant Evaluation Manager Richard Hawke finalizes data gathered on fragrance, hardiness, ornamental qualities, and disease resistance. Now those lavenders are being snapped up by horticulturists for their display gardens. Search the varieties found throughout the grounds on the Garden's Plant Finder to decide which fragrance and foliage most appeals to your yard. You can't plant too much lavender—all gardeners thrill to its cut-and-dried, fragrant flower stalks.

Witch hazel

Blooms in June

Also wrapping up at the Plant Evaluation Garden: a trial for witch hazels. An underused shrub in Chicagoland gardens, witch hazel can bridge the fragrance gaps of late winter and late autumn. Hamamelis vernalis, or spring-blooming witch hazel, is renowned for intensely fragrant flowers that are some of the earliest to bloom in the garden. And our North American native witch hazel, Hamamelis virginiana, is spectacular in autumn, when it flowers at the same time as its leaves turn golden yellow. Its fragrance is somewhere between sweet and intoxicating on a fine fall day. An earlier edition of Smart Gardener talked in depth about the ongoing witch hazel evaluation.

Lilac

Blooms in June

Some say that women are fonder of the scent of lilacsthan men. Nonetheless, there's room for a lilac in every garden, as dwarf forms tackle the issue of size and hybrids expand the color palette of purples, red-violets, pinks, whites, and blues. The Garden's Plant Information Service sorts out the differences (including fragrances) between common, Preston, Meyer, and Manchurian lilacs in the Plant Profiles section of the website.

Magnolia

Blooms May through June

Long used as a specimen plant in midwestern yards and gardens, magnolias can range in size from small shrub to giant tree. With cuplike blooms, glossy leaves, and citrus-y fragrance, a magnolia can be a true garden star. Located just inside the Sensory Garden, a sweet bay magnolia called Moonglow (Magnolia virginiana var. australis 'Jim Wilson') is a staff favorite for its lemon scent and bright orange-red fruits.

Chocolate cosmos (Cosmos atrosanguineus )

Blooms summer to fall

If your passion for gardening is trumped only by your passion for chocolate, search out a few plants of Chocolate cosmos. Its maroon/brown/near-black flowers have a velvety feel and can't-get-enough-of-it chocolate scent—you'll find it incorporated into containers around the grounds and in the Sensory Garden's raised beds. While perennial in its native Mexico, this cosmos can't handle Chicago winters in-ground; advanced gardeners can experiment with overwintering containers indoors.

Curry plant (Helichrysum italicum)

Blooms through summer

Take a tip from horticulturist Dale Whiting when it comes to fragrance (he presides over the Sensory Garden, where scented plants are a specialty): present one large, strongly scented plant in a big container for maximum impact in a small space. At the Circle Garden, which Dale also designs, Curry plant is strategically positioned in pots at the four corners of the garden, where its spicy scent draws questions and inspires conversations all summer long. Other options: a large rosemary topiary, a lush pot of basil, or cluster of scented thymes.

Geraniums (Pelargonium)

Blooms summer to early fall

Not all fragrance comes from flowers. The foliage of scented geraniums gives a creative gardener a fun scent palette to work with: lemon, rose, peppermint, pine, cinnamon, clove, chocolate mint, strawberry, and many more. Many of the leaves have interesting shapes and variegated colors, too. Plant scented geraniums near doors and sidewalks so you can rub the leaves and inhale deeply as you go by.