How to Grow and Care for New Guinea Impatiens

New Guinea impatiens (Impatiens hawkeri) provide a spectacle of blooms in any sunny garden location. Like their shade-loving cousins, the common impatiens, New Guinea impatiens form small clumps of foliage with colorful proliferating flowers. When planted just after the last threat of a frost, these fast growers will start to bloom early in the season, and some varieties will last well into fall. New Guinea impatiens offer a low-maintenance and high-performance option for gardeners wanting a showy seasonal display, free of fuss.

This variety of impatiens boasts pointy leaves, of dark green, burgundy, and variegated, which stay attractive throughout the season. Flower colors include shades of orange, pink, red, white, and purple, with blooms similar to, but larger than, those of common impatiens. The flowers of New Guinea impatiens consist of five heart-shaped petals. This plant makes a perfect addition to a pollinator garden, as the blooms attract butterflies and other beneficial insects.

New Guinea Impatiens Care

Most gardeners grow New Guinea impatiens as annuals, purchasing them as starts, and then transferring them to the garden. Expect your New Guinea impatiens starts to already be blooming, or to bloom early in the season. These flowers will continue to show their colors when given enough sun and water, and with very little maintenance. Keeping your garden free of weeds will assure proliferation and eliminate the competition for water.

Outside in containers, New Guinea impatiens provide an eye-level view of window brightening color all season long. They work great for edging a walkway or used in the front of a garden as a border. When incorporated this way, plant impatiens in a large block for a dramatic impact. Impatiens can also be grown as perennials in certain zones, and in pots as houseplants, yet don't expect them to flower year-round indoors.

Light

The amount of sun exposure your New Guinea impatiens need depends on the temperature and moisture of your climate. New Guinea impatiens do best with morning sun and afternoon shade in a garden with eastern exposure. If the sun is bright and the temperatures extreme, impatiens will require more water and may not bloom as profusely.

Soil

New Guinea impatiens like a slightly acidic soil pH, in the range of 6.0 to 6.5, but are not terribly particular. These flowers need well-draining soil that holds moisture long enough for their roots to soak it up. New Guinea impatiens are heavy feeders, so add a good amount of organic matter to the soil during planting time. Once in the ground, give your flowers a good drink of water to help them establish themselves.

Water

New Guinea impatiens thrive with regular waterings. Do not let them remain dry for an extended period of time or they will stop blooming and potentially die. New Guinea impatiens are not drought tolerant, yet prolonged periods of wet soil may cause their crowns to rot. Avoid watering them from the top, and use a drip hose instead, if possible.

Temperature and Humidity

Do not plant New Guinea impatiens outside until all danger of frost has passed and night temperatures are above 45 F. These flowers prefer day temperatures of 70 to 85 F and night temperatures of 55 to 65 F. They thrive in the high-humidity zones of 10, 11, and 12.

Fertilizer

Since New Guinea impatiens bloom all season long, they benefit from supplemental fertilizer. Give your flowers a dose of your favorite water-soluble food, specific for blooming flowers, every three to four weeks. You can also mix in some compost upon planting, or early and late in the season, when grown as perennials.

Types of New Guinea Impatiens

It's hard to recommend annual varieties since they are constantly being hybridized. You never know if this year's introduction will be available again next year, or if there will be an even better, improved version. However, the following New Guinea impatiens varietals are coveted by growers:

• Impatiens 'Paradise Rose Flair' is a top-performing variety, growing iridescent red-pink flowers all season long. This plant grows 16 inches both tall and wide.
• The sun-tolerant Impatiens 'Sun Harmony Baby Pink' yields 2-inch-wide soft pink flowers which bloom all summer. The plant's mature size is 20 inches tall and wide.
• For coral-colored blooms, choose Impatiens 'Sunstanding Salmon.' This cultivar can grow in shady to full sun areas and looks great grown in containers, as it maxes out at 36 inches tall and wide.
• Impatiens 'Sunstanding Glowing Scarlet' produces bright orange flowers with heart-shaped petals all summer long, and grows 36 inches tall and wide at full maturity.

Pruning

New Guinea impatiens require some mid-summer pruning in order to maximize the blooms. To do so, first, deadhead the flowers by pinching the stem back to its first set of leaves. You can do this regularly throughout the season. Next, look for areas where the stems have grown leggy and are producing more foliage than blooms. Cut back your impatiens no more than 6 inches (and starting from the center stems), should they become spindly.

If your flowers look full and free of holes, there is no need to prune your impatiens at all.

Propagating New Guinea Impatiens

New Guinea impatiens starts are readily available at most nurseries, lending you so much variety. Still, they are easily grown from cuttings should you want to save money or if you love the specific cultivar you planted.

Here's how to propagate New Guinea impatiens from cuttings:

1. Gather garden shears, alcohol wipes, a glass, a pot, and potting soil.
2. Disinfect your shears by swabbing the blades with an alcohol wipe.
3. Select a hearty stem and cut 4 to 6 inches below the bloom.
4. Remove the leaves from the bottom of the cutting, leaving only the top two leaves.
5. Place the bottom of the cutting in a glass of water and locate it in a sunny window until it begins to root.
6. Fill a pot with potting mix, water it, and allow it to drain.
7. Poke a hole in the soil and place your cutting into the hole, covering up all the roots and about 1 inch of the stem.
8. Place the pot in a sunny indoor location, and then harden it off by relocating it outside for several days before transplanting it into your garden.

How to Grow New Guinea Impatiens from Seed

Since New Guinea impatiens are hybrids, most varieties cannot be grown from seed, as they are either sterile or will not grow true to seed. However, there are a few cultivars that have stabilized enough so that seeds are available. These include the Divine Series, which comes in shades of white, pink, lavender, orange, and red, and the Tango, offering dramatic fluorescent orange flowers.

To grow impatiens from seed, make sure you're in it for the long haul, as seeds will need to be started indoors about three months before your average last frost date. Fill a tray, or a 6-pack of cells, with a seed starting mix and water the soil. Plant two seeds in each cell or broadcast seeds over the tray, covering them with a dusting of soil. Mist the top, and then cover your containers with plastic and locate them in a bright spot. Remove the plastic when two sets of leaves have formed and allow the seedlings to grow for three months before transplanting them into the ground.

Potting and Repotting New Guinea Impatiens

New Guinea impatiens make great potted flowers that can liven up your home's outdoor decor. To pot them, first select a container with good drainage. Next, create a false bottom in the pot by adding a thin layer of pebbles before filling the pot with soil. Take your impatiens starts out of their package and gently separate the roots at the bottom, if they seem root-bound. Relocate the starts to the container, making sure to place them to your liking, and to completely cover the roots. Water the pot and allow it to drain before placing it in a sunny location outside.

Since New Guinea impatiens grow relatively small and are mostly kept as annuals, repotting them is almost never needed.

Overwintering

Gardeners wanting to extend the life of their plants, as well as those wanting to relocate them outdoors come spring, can bring impatiens indoors during the winter. First, inspect the plant to make sure that it is free of pests and disease. Next, cut the plant back by a third, water it slightly, and relocate it to a sunny area in your home. (You may need to supplement with a plant light, if you don't have enough natural light indoors.) Come spring, cut your plant back by half, repot it in fresh soil, water it, and harden it off by bringing it outside during the day for a few days after the last frost. Once temperatures warm, relocate the pot to a sunny spot outdoors.

Common Pests & Plant Diseases

Like common impatiens, New Guinea impatiens can become infested with aphids and spider mites, which damage the plant by sucking its juices. Treat an infestation by first reducing the population with a spray from the garden hose. Then, spray the plant with insecticidal soap.

Necrotic spot and tomato spotted wilt can move into an inpatiens bed infested with thrips. There is no cure for these viruses, so prevention is crucial. Eliminating thrips will thwart the chances of disease moving in.

Downy mildew, botrytis blight, and verticillium wilt are fungal conditions that can affect impatiens with soggy soil. You can prevent this by maintaining a consistent watering schedule and increasing the space between plants when planting. Once these diseases move in, downy mildew can only be controlled by removing the diseased plant, while botrytis blight and verticillium wilt may respond to a fungicide.

How to Get New Guinea Impatiens to Bloom

New Guinea impatiens bloom best in an area that receives sun in the morning and shade in the afternoon. If your garden area receives more than eight hours of sunlight a day, you may need to provide a temporary shade structure in order to maximize blooms.

Maintaining proper moisture conditions will also affect flowering. Make sure your impatiens are not waterlogged, or they will drop their flowers and develop a red tinge to their leaves. If this happens, cut back on watering, but don't let the soil completely dry out.

Common Problems With New Guinea Impatiens

Like other flowers, New Guinea impatiens can actually get sunburned and develop a condition called marginal necrosis. Brown necrosis patches on leaves are not very serious, yet they create an unsightly display. The best way to avoid this is to make sure your planting area receives ample shade.