What's the difference between regular impatiens and New Guinea impatiens?

New Guinea impatiens is a different, more disease-resistant group, notably resistant to the downy mildew that has become a serious problem for classic Impatiens walleriana in many parts of Canada. New Guinea types also tolerate more sun and have larger flowers and leaves, though they typically cost more per plant.

Do impatiens need deadheading?

No — impatiens are self-cleaning and drop their spent blooms on their own, which is part of why they're such a low-maintenance choice for continuous colour in shade beds.

Plant care guide

Impatiens Growing Guide

Impatiens walleriana

Downy mildew has made classic bedding impatiens a genuine gamble in much of Canada in recent years — New Guinea impatiens is the disease-resistant alternative worth knowing about.

Light

Part shade to full shade; some morning sun tolerated

Soil

Rich, well-drained, moisture-retentive

Water

Consistent moisture; doesn't tolerate drying out

Hardiness

Annual across all of Canada; direct sow or plant after last frost

Mature size

20–60 cm depending on variety

Bloom time

Continuous from planting until frost

Impatiens walleriana has long been the standard shade-garden annual for continuous colour where almost nothing else blooms, but downy mildew — a disease that can collapse an entire bed within days — has made it a riskier choice in much of Canada over the past decade. Knowing the disease risk, and the disease-resistant New Guinea alternative, matters more with this plant than with almost any other bedding annual.

Planting

Plant outdoors only after all risk of frost has passed — impatiens are tender and killed instantly by frost
Choose a part-shade to full-shade site; too much direct sun causes wilting and scorched leaves even with adequate water
Space plants according to variety spacing on the tag — good airflow between plants reduces disease risk significantly
Work compost into the bed before planting for the rich, moisture-retentive soil impatiens prefer

Watering

Keep soil consistently moist — impatiens wilt dramatically the moment they dry out, though they usually recover once watered
Water at the base rather than overhead when possible, since wet foliage increases disease risk
Mulch around plants to help retain consistent soil moisture through hot spells
No deadheading needed — impatiens are self-cleaning and drop spent blooms on their own

Downy mildew — what changed

Impatiens downy mildew is a soil- and air-borne disease that can defoliate and collapse an entire planting of Impatiens walleriana within days, especially in cool, humid, wet conditions
There is no reliable home-garden fungicide fix once it takes hold — affected plants should be removed and disposed of (not composted) to reduce spread
New Guinea impatiens (a different species/hybrid group, sold separately) is highly resistant to this specific disease and is the safer choice in areas where downy mildew has been a problem
Good airflow (proper spacing) and watering at the base rather than overhead both reduce — but don't eliminate — the risk with classic impatiens

Want this whole guide as a printable PDF?

Everything on this page — quick facts, every section, and the FAQs — as a clean, print-ready PDF you can keep with your garden notes.

Frequently asked questions

This is the classic sign of impatiens downy mildew, a disease that can defoliate and collapse Impatiens walleriana plantings within days, especially in cool, wet, humid weather. There's no reliable home fix once it's established — remove affected plants and consider New Guinea impatiens, which resist this disease, for future plantings.