What IS this thing?

Our first house had lots of garden space, but nothing growing there—the result of the previous owners’ German shepherd using the enormous raised bed as a dog run. Every corner of the yard was pawed to bare earth, too. So when the dog left and we arrived, things started popping up everywhere, and I had no idea what to yank and what to leave alone. Spring can be a crucial time for both. Leave something dreadful in place for even one season, and you may have hell to pay when you try to get rid of it later. And you don’t want to yank something that might turn out to be lovely. Well, we’re here to help. Here’s a guide to identifying some of the things you might see in your garden—the good, the bad and the ugly.

Autumn Joy Sedum. A tough plant that will grow just about anywhere—sun, shade, good soil, lousy soil. Plants stay compact and produce pink flowerheads that gradually darken to red, then rust. Blooms last well into autumn, when lots of other plants are packing it in for the year. They require virtually no care; just snap off the dead flower stems late in the season, or in spring.

Bleeding heart. A lovely spring bloomer with red or white heart-shaped flowers. Grows best in shade and may reseed itself, which is a wonderful thing. Foliage will die back after flowering; then just cut it back to the ground and wait for it to bloom again next spring. I've had good luck letting these go to seed and randomly scattering the dried flowerheads around in shady spots.

Buckthorn. Run for your life. A garden scourge, this invasive plant is banned in many areas. If left to its own devices, it forms enormous tree-like shrubs with long, ugly thorns. Easy to yank up when small; if you're cursed with one that has a woody stem, your only hope is to cut back the foliage religiously. Good luck.

Columbine. A shade garden star with blooms in a rainbow of colors. Some experts recommend deadheading to prevent self-seeding, as the offspring may be aggressive, but I've never found that to be a problem in my garden.

Cranberry cotoneaster. This is perfectly useful shrub that can be pruned into hedges or trimmed back to a low-growing groundcover. If it pops up in a garden, though, give serious thought to whether you have space for it. It will spread rampantly without pruning; I had some that were 5 feet tall. Kept in bounds, though, it's nice enough. Pink flowers in spring, red fruits later in the season.

Creeping Jenny. Low-growing ground cover that spreads readily, yet is easily snipped back to keep it in bounds. I have this planted in shade gardens and around my patio, where it is busily covering the hideous volcanic rock the previous owners dumped everywhere. It produces bright yellow flowers in early summer and is utterly care-free. Transplants easily, too.

Daylily. There about a bazillion types of daylilies available in every color imaginable. Blooms last only a day, but they flower so heavily it doesn't really matter. Deadhead them to keep the plants looking tidy. My favorite: the peachy-gold Stella D'Oro.

Dianthus. This is a low-growing plant, nice for rock gardens. Also known as pinks, but the flowers may be white or red. I have them growing in both sun and shade; those growing in sun are a little more vigorous, but the red is lovely in a shade garden. Easy-care; plant it and forget it.

Greek oregano. This plant functions as a perennial in my Zone 5 garden. It's a fine addition to your herb garden, and mine grows equally well in sun and shade. But beware—it will spread like crazy. Keep pinching it back and don't let flowers form; that will help prevent unwanted volunteers.

Hosta. Lucky you. This is one of the easiest shade plants imaginable—lovely and tough. Leaves may be variegated or puckered, and there's a size to fit every space. Smaller varieties are no bigger than a salad plate; others are massive, with spreads of up to 5 feet. Flowers on tall stalks are borne in late summer; some are fragrant. Divide in spring or fall; easy as pie.

Hyacinths. Bulbs that produce showy flower spires in spring. The fragrance is luxuriant and lush; cut one flower for a bud vase and the scent will perfume an entire room. Plant in fall, preferably near a door or window where you can appreciate the perfume.

Lungwort. This plant is new to my garden, and I love it already. The flowers emerge pink, then change to blue or white; luckily, I managed to capture it with all three colors showing. Best in moist shade. Blooms in spring, and it's cold-hardy.

Raspberry. Great if you have room to let them spread, because they will. In the yard, not so much. You can yank them out when they're this size; if you let them get much bigger, look out.

Solomon's seal. Quite the charmer, this native plant thrives in shade and produces fragrant white flowers in spring; they look like dainty droplets beneath the leaves. This one's new to my garden, so I don't know whether it's true Solomon's seal or false Solomon's seal. The former produces blue berries; the latter, red. I'll update once the berries show up.

Spider plant (cleome). These annuals are spectacular in bloom, with pink and white flowers and seed pods that dangle and look—well, spider-like. It's been two years since I bought any spider plants, because they just keep re-seeding themselves—a boon for tightwad gardeners. They're tall, showy plants and need a fair amount of room; good for the back of the border. Bonus: Their mildly funky scent repels mosquitoes.

Squill. Pretty, isn't it? This spring-blooming beauty is nice in rock gardens. It's a bulb, so plant in fall. Allow the foliage to die back completely before you remove it; as with daffodils, the bulbs need the foliage to store nutrients for the next year's blooms.

Sweet woodruff. A tremendously useful ground cover that spreads rapidly. Thrives in shade, although I have some growing in sunny spots as well. Lushly fragrant white fllowers in spring, but the foliage keeps its nice green color throughout the growing season. Plant it near a window so you can appreciate the perfume.

Thistle. Boo, hiss. There are a zillion types of thistle, and I don't know which type this is, but it doesn't really matter: They're all horrible. Even a small one like this has spikes that will poke right through your garden gloves. And once they get bigger, so do the spikes. Dig it out and get rid of the entire taproot. Use a shovel and dump it into your muck bucket without touching it, or you'll be sorry.

Violets. Aww. Nice, aren't they? Sure, if you don't mind them spreading into your lawn, where they are devlishly difficult to eradicate without chemicals. I have a few I'm leaving under some ugly shrubs in a rarely visited area of the yard, but in general these are best dug up by their persistent little rhizomes and tossed.

Wild strawberry. Maybe there is a place for these things, but in my garden it just chokes out more desirable groundcovers. The berries are so small and insigificant the woodland creatures that frequent my yard don't even touch them. The worst part? They creep into the grass, where they are much more difficult to pull up. A pox.

Yarrow. Not the prettiest plant on the block, but it will stand up to rotten conditions and drought. Flower color varies; this one is yellow.