New Guinea impatiens received their name from their native island. After significant modifications to the cultivars over the years, the current varieties are easy to grow and very popular among home gardeners. The blooms can be orange, red, pink, white or purple. New Guinea impatiens prefer more shade than sun, although they can tolerate morning sunshine. Make sure you protect your tender impatiens plants from cool overnight temperatures.
Prepare the growing area after the last expected frost date in the spring. Work the soil down several inches with the spade. Add 1 to 2 inches of compost and 0.454kg. of slow-release fertiliser for each 100 square feet of growing area. Use the spade to work the compost and fertiliser in completely and rake the surface smooth.
Dig holes for the seedlings so that they will be at the same depth as they are in their temporary pots. Space the holes approximately 4 inches apart. For best results, do not transplant the seedlings into the ground during the heat of the day. Place the plants into the holes and refill with soil. Firmly tamp the soil and water generously.
Give New Guinea impatiens enough water throughout the growing season so that the soil stays evenly moist. Do not let the plants dry to the point of wilting. When the weather is cool, provide less water; when the weather is hot, provide more water. Mulch around the plants to control weeds and keep the soil moist and cool.
Fertilise the plants every third time you water. Mix the fertiliser with water according to package directions and water until the plants are moist. If the soil is dry before you fertilise, water the impatiens first and then fertilise to avoid burning the plants with fertiliser.
Trim the plants if they become tall and thin. Cut the stems back to the point where the leaves intersect with the stem (a leaf node). This will encourage the plant to grow bushier.
Cover the plants with a blanket if overnight temperatures will fall below 7.22 degrees C.
Some gardeners are cautious and prefer to wait one or two weeks after the anticipated last spring frost to make sure their impatiens will not be outside in cold overnight temperatures.