New Guinea Impatiens, named for their native habitat of Papua New Guinea, have been a mainstay in spring and summer programs since their introduction the US in 1972. Years of breeding and hybridization have made this plant a versatile choice in landscape, baskets and combination planters for many growers.
General Growing Tips For Your Rooted Cutting Liner
For best results with New Guinea Impatiens, we recommend using a constant feed program of 100-150 ppm N. Maintain a pH between 5.8 - 6.2. New Guineas are very susceptible to salts injury so ensure proper run-off and plan for a clear water drench weekly.
Pinching
Pinchingis not recommended as New Guineas are free-branching plants. Pinching will delay flower production by 2-3 weeks, so it can be used as an effective timing tool to delay flowering.
Spacing
Spacing too close will result in excessive stretching. Space pots adequately to allow for light penetration and airflow between foliage of adjacent pots. We recommend seven inches for 4” pots and eighteen inches for 10” pots.
Height Control
Stretching is best controlled with high levels of light, proper watering, and low fertilization. If PGRs are desired for varieties that stretch, NC State has tested a foliar spray of Bonzi at 5-30 ppm with good results.
Pests
Spider mites and thrips are the primary pests attracted to New Guinea Impatiens.
Disease
Harmony Red Cardinal are not prone to many diseases, but watch for botrytis while the days are short. This grey rot is usually associated with wet or humid conditions. You can prevent botrytis by allowing the plant to dry out between waterings, allowing for good airflow in your greenhouse, and spacing to allow the sun to penetrate to the soil level. The most common chemicals used to treat botrytis are Medallion and Banrot. Use them as a drench according to each label’s instructions.
Planting Harmony Red Cardinal Liners
We recommend planting 4 starter plants per 10 inch basket. Use a well-drained soil in your baskets and plant your starter plants deep, allowing the ellepot to be completely covered by the soil. If you are planting 4” pots, 1 plant per pot should be sufficient if you have enough time. Plant it directly in the middle of your pot.
Pinchingis not recommended.
Rooted Cuttings
Cuttings vary in size between different plant families. These rooted starter plants will arrive ready to be transplanted in to your final container. If they are to be used in a landscape application, you will need to establish them in a 4 inch pot or an 1801 before planting outside.
New Guinea Impatiens Harmony Red Cardinal Quick Reference Guide
4 Inch crop time
4-6 Weeks
10 Inch crop time
8-10 Weeks
Bloom Period
Fall, Spring, Summer
Color
Red
Habit
Mounding
Height
18-48 Inches
Light
Partial Shade
Minimum Temp
55
Water Needs
Moderate
Patented Plant
Yes
Current
Availability
Current Availability
03-09-2026 (Week 11)
0
03-16-2026 (Week 12)
0
03-23-2026 (Week 13)
2,800
03-30-2026 (Week 14)
5,600
04-06-2026 (Week 15)
7,200
04-13-2026 (Week 16)
9,000
04-20-2026 (Week 17)
8,500
04-27-2026 (Week 18)
9,000
05-04-2026 (Week 19)
9,000
05-11-2026 (Week 20)
8,100
05-18-2026 (Week 21)
8,100
05-25-2026 (Week 22)
8,100
06-01-2026 (Week 23)
6,700
06-08-2026 (Week 24)
6,700
06-15-2026 (Week 25)
6,700
06-22-2026 (Week 26)
6,700
06-29-2026 (Week 27)
6,700
07-06-2026 (Week 28)
6,700
07-13-2026 (Week 29)
6,700
07-20-2026 (Week 30)
6,700
07-27-2026 (Week 31)
6,700
08-03-2026 (Week 32)
13,500
08-10-2026 (Week 33)
13,500
08-17-2026 (Week 34)
13,500
08-24-2026 (Week 35)
13,500
08-31-2026 (Week 36)
13,500
09-07-2026 (Week 37)
6,700
09-14-2026 (Week 38)
6,700
09-21-2026 (Week 39)
0
09-28-2026 (Week 40)
0
10-05-2026 (Week 41)
0
10-12-2026 (Week 42)
0
10-19-2026 (Week 43)
0
10-26-2026 (Week 44)
0
11-02-2026 (Week 45)
3,800
11-09-2026 (Week 46)
5,100
11-16-2026 (Week 47)
6,300
11-23-2026 (Week 48)
0
11-30-2026 (Week 49)
0
New Guinea Impatiens, named for their native habitat of Papua New Guinea, have been a mainstay in spring and summer programs since their introduction the US in 1972. Years of breeding and hybridization have made this plant a versatile choice in landscape, baskets and combination planters for many growers.
General Growing Tips For Your Rooted Cutting Liner
For best results with New Guinea Impatiens, we recommend using a constant feed program of 100-150 ppm N. Maintain a pH between 5.8 - 6.2. New Guineas are very susceptible to salts injury so ensure proper run-off and plan for a clear water drench weekly.
Pinching
Pinchingis not recommended as New Guineas are free-branching plants. Pinching will delay flower production by 2-3 weeks, so it can be used as an effective timing tool to delay flowering.
Spacing
Spacing too close will result in excessive stretching. Space pots adequately to allow for light penetration and airflow between foliage of adjacent pots. We recommend seven inches for 4” pots and eighteen inches for 10” pots.
Height Control
Stretching is best controlled with high levels of light, proper watering, and low fertilization. If PGRs are desired for varieties that stretch, NC State has tested a foliar spray of Bonzi at 5-30 ppm with good results.
Pests
Spider mites and thrips are the primary pests attracted to New Guinea Impatiens.
Disease
Harmony Red Cardinal are not prone to many diseases, but watch for botrytis while the days are short. This grey rot is usually associated with wet or humid conditions. You can prevent botrytis by allowing the plant to dry out between waterings, allowing for good airflow in your greenhouse, and spacing to allow the sun to penetrate to the soil level. The most common chemicals used to treat botrytis are Medallion and Banrot. Use them as a drench according to each label’s instructions.
Planting Harmony Red Cardinal Liners
We recommend planting 4 starter plants per 10 inch basket. Use a well-drained soil in your baskets and plant your starter plants deep, allowing the ellepot to be completely covered by the soil. If you are planting 4” pots, 1 plant per pot should be sufficient if you have enough time. Plant it directly in the middle of your pot.
Pinchingis not recommended.
Rooted Cuttings
Cuttings vary in size between different plant families. These rooted starter plants will arrive ready to be transplanted in to your final container. If they are to be used in a landscape application, you will need to establish them in a 4 inch pot or an 1801 before planting outside.
New Guinea Impatiens Harmony Red Cardinal Quick Reference Guide
4 Inch crop time
4-6 Weeks
10 Inch crop time
8-10 Weeks
Bloom Period
Fall, Spring, Summer
Color
Red
Habit
Mounding
Height
18-48 Inches
Light
Partial Shade
Minimum Temp
55
Water Needs
Moderate
Patented Plant
Yes
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