In northern United States and areas with similarly cold winters, the traditional time for planting impatiens is Memorial Day, when the danger of frost has passed, so the garden can bloom with these fast growers by late spring and summer.
How to Plant Impatiens
Plant impatiens in any moist, well-drained soil in a shady or semi-shady location. It’s best to plant them in late spring after the soil has warmed to at least 60 degrees Fahrenheit. If planted in soil that is too cold, these plants will languish for the entire growing season. Space the plants 10 to 12 inches apart. After planting, pinching back the stems will encourage bushier growth. Impatiens will grow wonderfully in almost any pot with good drainage—any pot material will do. As a general rule, you can fit 1 plant for every 3-4 inches of pot diameter. Impatiens, especially the New Guinea type, work well as a filler, too, in a container of mixed plants that prefer shade. Use a standard commercial potting mix. You can expect to fertilize and water more frequently for container-grown plants.
Light
With sufficient water, standard impatiens can be grown in a partly sunny location in northerly regions, but their greatest virtue is that they thrive in the shade. In fact, they’re among the relatively few readily available, inexpensive flowering plants that will put on a great summer-long floral display even when grown in full shade.
Soil
Grow standard impatiens flowers in well-drained soil enriched with organic material. They prefer a slightly acidic soil with a pH range of 6.0–6.5. The soil must drain well to avoid becoming boggy from the frequent watering that impatiens require.
Water
Once in the ground, standard impatiens will need at least 2 inches of water a week. When temperatures average consistently above 80 degrees Fahrenheit, water the plants at least 4 inches weekly. In window boxes and hanging pots, impatiens may need watering daily, especially if the daily temperature rises above 85 degrees Fahrenheit.
Temperature and Humidity
Impatiens are quite sensitive to heat. If there has been a long, dry spell, your plants will likely look wilted. Thankfully, they bounce back quickly once they are given water. Impatiens are fine growing in humid weather.
Fertilizer
Impatiens will flower best if regularly fertilized. A water-soluble fertilizer can be used every two weeks throughout the spring and summer. Another option is a slow-release fertilizer used at the beginning of the spring and again halfway through the summer. For the amount to use, follow product label instructions.
Types of Impatiens
There are more than a thousand varieties of impatiens. Standard impatiens may still be hard to find, since mildew-resistant varieties are still being developed and introduced. Your best selection may come with New Guinea impatiens. Some recommended varieties of standard and New Guinea impatiens include:
Impatiens walleriana ‘Imara XDR’: This line is a new disease-resistant line of standard impatiens from the Syngenta company, which became available in 2019. There are seven colors as well as color mixes in this series, which promises to restore standard impatiens to their former popularity.Impatiens walleriana ‘Beacon’: This is another series of standard impatiens that is “highly resistant” to mildew, introduced in 2020. Beacon is derived from the Super Elfin line, with many colors available.Impatiens hawkeri ‘Celebration’ series: This is one of the best of the New Guinea impatiens. Available in a wide range of vibrant colors, these plants grow to 16 inches tall. These plants were likely hybridized with other species of impatiens.Impatiens x ‘Bounce’ series: Developed by Ball Horticultural Company, this hybrid series of impatiens is a cross between New Guinea and standard impatiens. According to the company, they are resistant to downy mildew and thrive in sun and shade. It “bounces back” nicely after wilting in hot weather.Impatiens x ‘SunPatiens’ series: This variety has unusually large flowers (up to 3 inches across) in a unique shade of salmon pink. At up to 3 feet tall, the Sunpatiens line is across between New Guinea impatiens and standard impatiens species.
Pruning
If your impatiens plants start looking leggy late in the summer, use sterile, sharp garden scissors to trim off the top third of their vegetation. This will promote the emergence of new blooms and improve the overall appearance of the plants.
Propagating Impatiens
Impatiens will readily self-seed themselves, even in colder climates, though it may take most of the following year’s growing season before the seeds produce flowering plants. For this reason, it is easier to propagate impatiens from cuttings taken in the fall. Here’s how to propagate impatiens with cuttings:
How to Grow Impatiens From Seed
Impatiens flowers take their name from the Latin, impatiens, meaning “impatient.” They are so-called because their ripe seed pods will sometimes burst open from even a light touch (as if they were impatient to open). Some gardeners also collect seeds from these “exploding” pods that the plants produce in late summer and fall, then start them indoors in a seed-starting mix in later winter, six to 10 weeks before the last frost. When impatiens are planted from seeds, it can take several months for them to mature into flowering plants. Here’s how to plant impatiens from seeds.
Potting and Repotting Impatiens
It’s generally not necessary to repot impatiens, as they are usually discarded at the end of the growing season. Although these plants are perennial in warm conditions, they can be susceptible to mites and other insect pests when moved indoors. The best strategy is to cut back the stems to 3 inches or so, then give them a sunny location and slightly less water through the winter. Withhold fertilizer through the winter months. Although these plants do not go dormant, they are most likely to survive if allowed to slow down their growth for the winter months.
Overwintering
Impatiens are tropical plants that will turn to mush at the first light frost. Pull up and discard these plants to prevent pathogens from overwintering. Potted plants can be similarly discarded; or, bring them indoors if you plan to keep them over the colder months.
Common Pests & Plant Diseases
The popular impatiens fell out of favor in 2004, when a particular form of downy mildew appeared and quickly decimated breeding stock in commercial nurseries across North America. This disease is caused by a pathogen called Plasmopara obducens, and for more than a decade, it virtually stopped all commercial sale of standard impatiens. Standard impatiens did not begin a comeback until 2019, with the development of a few mildew-resistant hybrids. Aside from the downy mildew that devastated the standard impatiens, these plants can be affected by viruses, fungal blights, and rots. These problems are more likely in humid, wet conditions, or where plants are crowded closely together. Impatiens experience insect problems, including aphids, mealybugs, thrips, whiteflies, slugs, snails, and spider mites. Severely affected plants can be removed; minor infestations can be treated with horticultural oils or pesticides.
How to Get Impatiens to Bloom
Impatiens are among the most prolific bloomers of all flowering plants. You can generally expect profuse blossoms from late spring right up until killing frost. If your impatiens are blooming less robustly than you like, try pruning back the leggy stems, which usually stimulates new bud growth. Reduced blooming can also be the result when plants get too much sun, not enough water, or too much fertilizer.
Common Problems With Impatiens
Though these easy-to-grow blooms can generally be left alone, they will present a couple of common challenges.
Legginess
One possible cause of impatiens becoming leggy is over-fertilization.
Scorched Leaves
Too much sun may scorch the leaves on most varieties of impatiens, though the New Guinea varieties can usually tolerate full sun if given extra moisture.
