You hear it so often, it’s a cliché. “I want to grow beautiful flowers for my garden, but everything I plant dies.” Dead outdoor plants can happen for many reasons. Sometimes, we plant flowers for the garden that need more sun or shade than we can give them, or there's a drought, or pests and diseases move in and send our poor dahlias, roses and other flowering plants to the compost pile.

Instead of trying to grow needy outdoor plants, opt for some easy flowers to grow, such as sunflowers and morning glories. You can find easy-care flowering perennials for season-long color, and, when they're finished, fill in with annual flowers for year-round color. Read on for more "can't-kill flowers" for beginners to grow.

Plant them in full sun to part shade, and carefree Siberian irises (Iris sibirica) will bloom in early summer. After the flowers finish, don't remove the leaves. They'll soak up the sun to power the next season's blooms and die back naturally. In the meantime, they'll add texture to the garden. You can find Siberian iris in many colors, including purple, blue, gold, pink, white and burgundy. Give them moist soil, and they'll grow 34 inches tall by 18 to 24 inches across. They're hardy perennials in USDA Zones 3 to 9.

Portulaca (Portulaca grandiflora), or moss rose, is a tough annual that grows happily in full sun and average, well-draining soil. This succulent has thick leaves, so it can tolerate some drought. Use its colorful carpet of blooms as a groundcover or grow portulaca as a bedding plant. This variety, 'Mojave', is a mix of cheerful red, pink, tangerine orange and yellow flowers. It's easy to grow from seed, but don't transplant it into your garden until after your last spring frost.

Although catmint (Nepeta spp.) is an ornamental relative to catnip, its unscented leaves are less likely to attract felines to your garden. (Bees and butterflies love them, though.) This is an easy-to-grow, perennial herb valued for its lavender-blue flowers and gray-green foliage. Catmint doesn't mind drought, heat or average soil and thrives in full sun to part shade. It grows so easily, that it can invade other areas. You may want to grow it in pots or put edging around it. Shown here: Catmint (Nepeta x faassenii) 'Purrsian Blue'.