Filling up a big spot in a garden bed can be pretty easy. But what if you want volume (height or width or both) without bulk–as in heavy, leafy, darkness-inducing shrubs? Look to the frothy fronds of fennel and asparagus offering the softest forms there are in the plant world. They offer a lot of volume while still keeping things light and airy. And you can add some of these edible plants to an ornamental garden in interesting (read: unexpected, possibly awe-inspiring) ways.

Fennel love

Bronze fennel’s dark laciness hides the bare legs of a climbing rose at Longwood Gardens. July, 2023.

Fennel has deeply divided, ferny leaves that are divinely fragrant. Taller, more vigorous and living longer than its distant cousin dill, fennel does it all plus is a heroic supporter of wildlife, including certain types of swallowtail butterfly. Foeniculum vulgare ‘Purpureum’ (Bronze Fennel) makes a particularly gorgeous backdrop, contrast or accent to other plants because of its darker, purply/brown colouring.

TRY USING BRONZE FENNEL:

• as an accent in a bed full of Echinacea. When the coneflowers are in full, bright bloom, a bronze fennel will add a bit of softening with its darker featheriness plus hits of mustardy yellow from its own flowers.
• in a desert-themed garden. Fennel is drought tolerant, once established, so it’s a great addition to any xeriscaping project. The dark, feathery leaves are a nice contrast to the smooth shapes and light colours of gravel mulch and its form gives off a kind of tumbleweed vibe.
• when you want to help wildlife. Fennel flowers are a magnet to bees, butterflies and beneficial insects and, in the fall, birds love the seeds.
• in a cutting garden. Asparagus isn’t the only plant to offer lovely sprays to fill out a bouquet. Fennel’s dill-like flowers and ferny fronds make excellent fillers in an arrangement.
• in a grouping of gold and light green ornamental grasses for a simply extraordinary celebration of colour and texture.

Asparagus inspirations

A long, curving and very narrow hedge of asparagus at Chanticleer Gardens. July, 2023.

Asparagus (Asparagus officinalis) is, admittedly, a little trickier to grow. For instance, you have to consider its sex. Yup, asparagus can be male or female and each has its own unique charactertistics (see Asparagus Tips, below). You also have to be cautious about buying only disease-free, one-year-old crowns (faster than starting from seed) and planting them in trenches, etc. Your best bet is to look up a good asparagus growing source such as University of Saskatchewan’s tip sheets. But asparagus will reward your patience and a little extra work with long-lived beauty that has an exceptional elegance.

TRY USING ASPARAGUS:

• in a row along the top of a berm or the crest of a large mounded bed. The long roots of the plant will benefit from the extra depth of the soil and the wispy fronds will add the glamorous equivalent of ostrich plumes on a hat.
• instead of shrubs for a hedge when you want some sort of demarcation but you want it to be sheer and ethereal (like how it was done at Chanticleer, shown above).
• when you want a dramatic backdrop to a bed but you don’t have a lot of room. Asparagus grows tall but a single row only needs about 18 inches of room from front to back.
• where you want a little fall interest. After a hard frost, the dead fronds will turn golden brown and curl up a bit but continue to add a nice frothiness in contrast to the linear outlines of woody shrubs without their leaves.

Asparagus stalks add height and interest in the corner bed of a front garden in Gananoque, Ontario. July, 2023.

Frothy but finicky frond stars

If you love both plants, keep this in mind: Fennel and asparagus do not play well together. Fennel will compete for space with asparagus. Quite frankly, I figure you’d only want one or the other in an ornamental garden in any case. One tall spout of froth can go a long way.

In addition, fennel seeds contain allelopathic chemicals which suppress the growth of vegetables (including asparagus) so don’t plant fennel near your veggie patch. You won’t have any trouble if you plant fennel in your flower garden. however. Interestingly, I’ve read that dill, being a close relative of fennel, is one edible plant that isn’t affected by this suppression. If you want to go all in with over-the-top feathery plants, dill could look great alongside fennel.

Go froth and prosper

FENNEL FACTORS

• Grown as an annual in Canada
• Needs moist, organically rich, well-drained soil
• Full sun
• Freely self seeds (which can be an issue)
• Some varieties grow to 5 feet tall.
• Tiny yellow flowers in compound umbels in mid- to late summer
• Doesn’t transplant well so sow seeds directly into the ground after last frost and ground is no longer cold
• Drought tolerant once established

ASPARAGUS TIPS

• Grown as a herbaceous perennial in Canada
• Hardy in zones 2 to 8
• Needs sandy, sandy loam or loam soil that is well draining
• Full sun
• Grows over 5 feet tall
• Develops a root system and takes several years before a large patch is established
• Asparagus plants can be either male or female. If you’re purchasing plants simply as ornamentals, keep these factors in mind:
  • Male plants grow thicker and taller
  • Female plants produce little red berries which can eventually produce tiny plants that can make your asparagus patch quite weedy rather quickly.

Happy frothing!