I’m addicted to spikes, spears, and swords. I’m not talking about medieval weapons; I’m talking about edgy, architectural plant forms that invigorate gardens with excitement. Give me a planting to design, from urban verandas to country courtyards, and I just can’t resist including a mix of spiky plants like yuccas, agaves, or prickly pear cacti. These plants always deliver, adding striking, structured form with their narrow leaves, pointy spines, and toothed edges.

Although many gardeners consider spiky plants strictly Southwest or desert inhabitants, these brash beauties are bucking their tender or difficult reputations by proving to be strong seasonal performers from Philadelphia, Penn­sylvania, to Portland, Oregon. Given the right soil, drainage, and sun exposure, many spiky plants are hardier and more adaptable than gardeners may think.

Because spiky plants come in a vast array of forms, textures, and sizes, they can be used to add drama just about anywhere. The most successful designs feature small spiky plants in masses or groups and showcase large specimens as focal points, while pairing them all with companions that have complementary forms and similar cultural needs.

When designing with spiky plants, especially rosettes (plants with clustered leaves arranged like a rose blossom), recite this mantra: “Repetition, repetition, repetition.” These plants can look out of place without some spiky cohorts; by planting together several of one variety or similar-looking species, you can make the whole creation look purposeful, connected, and a bit more natural. Plants can be repeated in a mass planting or in multiple, smaller groupings throughout an area or garden. This approach is particularly effective when using small plants like flat sea hollies (Eryngium planum and cvs., USDA Hardiness Zones 5–9) and dollhouse yucca (Yucca harrimaniae, Zones 5–9).

Whether you are using spiky plants in groups or displaying them as focal points, pay attention to their neighbors. Try to avoid dueling bold forms and textures that compete for attention, like a prickly pear cactus or agave next to your favorite peony (Paeonia spp. and cvs., Zones 3–8). Instead, start simply and create drama by combining spiky plants with soft, contrasting fine textures and loose forms, like those of orna­mental grasses or artemisias (Artemisia spp. and cvs., Zones 3–9). Another trick is to establish harmony by choosing companions with similar characteristics, like bluish gray color, smooth-cut leaves, or starburst form.

Perhaps the easiest way to design with spiky plants is to use them as the overall theme for a bed or garden room. They provide an exotic look, which can be rounded out and highlighted with the unobtrusive forms of small grasses and clumping plants, such as sedums (Sedum spp. and cvs., Zones 3–9) or buck wheat (Eriogonum spp. and cvs., Zones 3–11), and shrubs, such as dwarf conifers, Apache plume (Fallugia paradoxa, Zones 5–10), or Japanese holly (Ilex crenata and cvs., Zones 5–8).

Attention to growing needs is, of course, an important part of gardening with spiky plants. Though most species prefer full sun or a bit of afternoon shade in the hottest climates, a surprising number of spiky plants will tolerate partial shade. Many species are native to drier habitats and have adapted their shapes to conserve water. They do appreciate, however, occasional water in summer. Although some spiky plants will handle damp soil, a good rule of thumb is to provide all spikes with sharp drainage (soil that does not retain much moisture and drains quickly). I amend planting beds with pumice, perlite, gravel, or sand. This helps with drainage in all but heavy soils (in the latter, these ingredients end up resembling an adobe brick).

If you do garden in heavy soil, consider growing spiky plants in containers, where you have more control over the soil conditions. Because containers are portable, they also allow you to experiment with your planting schemes. Be aware, however, that plants in containers don’t grow as large because root space is limited. More attention to water needs is also required, and if you are concerned about hardiness, remember to subtract a zone from the plant’s expected frost hardiness. Plants in containers are, of course, more susceptible to cold temperatures.

Finicky tender plants can be stored in a protected location to sustain them through the winter. Bring potted plants indoors from the cold and place them in a greenhouse, basement, or sunroom, or even on the living-room floor. Plants enjoying indoor warmth benefit from bright light and are best kept on the dry side to minimize any new growth. Once the threat of frosty temperatures has ceased in spring, plants can be moved back outdoors. Make the transition gradual, placing your babies in the shade for a while, slowly exposing them to a full-sun position.

In areas where plants are borderline hardy and left in the ground, you may need to provide temporary protection from time to time. For heavy winter precipitation, a common danger, consider a water-shedding cover such as a simple, clear umbrella or a Plexiglas roof—a method often used in rock gardens—for smaller specimens. When temperatures briefly hover on the cold side, use old blankets, towels, sheets, or even burlap as temporary covers.

For the best results with your spiky plants, learn as much as possible about your choices, especially their tolerances for cold, drought, light, and soil types. Don’t be afraid to push the envelope. Fearless gardeners are learning that these plants can grow in and add excitement to the garden in the least expected places.