Impatiens vs Begonia: Which Shade Annual Blooms Longest and Needs the Least Work?
One is pet-safe and thrives in deep shade. The other survived an epidemic that cut US wholesale sales by $85M. Here’s which shade annual wins in your garden.
For most of the twentieth century, impatiens owned the shade garden. They were the default fill plant — dense color, reliable bloom, easy to find at any garden center in May. Then, between 2011 and 2012, a fungal-like pathogen called Plasmopara obducens swept through impatiens plantings across 33 US states and within a year had reached Hawaii. The national wholesale value of impatiens dropped from approximately $150 million in 2005 to $65 million by 2015. Begonias — already a staple for sun-and-part-shade plantings — moved in to fill the gap.
Today, both plants compete for space in shade borders and containers. They look similar at the garden center: low-growing, floriferous, available in pinks and reds and whites. But they have genuinely different requirements, different vulnerabilities, and very different suitability for specific situations. This guide breaks down every meaningful difference so you can pick the right plant for your exact conditions — not just follow a general recommendation.
Quick Comparison: Impatiens vs Begonia
| Feature | Impatiens walleriana | New Guinea / SunPatiens | Wax Begonia | Dragon Wing Begonia |
|---|---|---|---|---|
| Light | Filtered/partial shade only | Part sun to full sun | Full sun to deep shade | Part shade to shade |
| Water needs | High — never let dry out | Moderate | Moderate; short drought OK | Moderate |
| Height | 10–18 inches | 18–36 inches | 6–12 inches | 24–36 inches |
| Downy mildew risk | High | Resistant | None | None |
| Deer resistant | No | No | Yes | Yes |
| Pet safety | Non-toxic (ASPCA) | Non-toxic (ASPCA) | Toxic — oxalates | Toxic — oxalates |
| Deadheading | Self-cleaning | Self-cleaning | Not needed | Not needed |
| USDA zones (annual) | 2–11 | 2–11 | 2–11 (perennial 9–11) | 2–11 |
How They Differ in the Garden
Light: The Key Dividing Line
This is where the two plants diverge most sharply.
Walleriana impatiens need filtered or partial shade. UMN Extension recommends keeping them out of locations that receive afternoon sun — in direct afternoon light above Zone 6, leaves scorch and flower production collapses. This is not finicky behavior. Impatiens walleriana evolved in the shaded understory of East Africa, and its photosynthetic system is calibrated for low ambient light. Put it in a spot that gets brighter over the season as surrounding plants die back, and you will notice the decline within a week.
Wax begonias tolerate a far wider light range. NC State Extension notes they adapt to conditions from full sun (6+ hours) to deep shade. The key variable is leaf color: bronze-leafed cultivars perform best in sunnier spots because the anthocyanin pigmentation acts as a photoprotective screen, reducing photoinhibition in high-light conditions — the same mechanism that allows other succulent-like plants to survive exposed beds. Green-leafed wax begonias do better with morning sun and afternoon shade, but they handle variable light far more gracefully than walleriana.
New Guinea impatiens and SunPatiens occupy a practical middle ground. They prefer morning sun with afternoon shade or bright filtered light, handle more sun than walleriana, and produce larger individual flowers. In intense full afternoon sun in Zones 6–7 summers, flowers can bleach, but the plants do not collapse the way walleriana does.
The short version: if your shade bed catches any afternoon sun, walleriana will struggle — begonias will not.
Water Needs
Walleriana is a high-water plant. UMN Extension advises watering when the top 1–2 inches of soil dries out; in containers during summer, that means daily checking. The soft, hollow stems wilt visibly within hours of moisture stress. Clemson HGIC emphasizes mulching as nearly mandatory to maintain consistent soil moisture. Forget to water impatiens in a hanging basket over a July weekend and you come home to a brown wreck.
Wax begonias are meaningfully more drought-tolerant. Their thick, succulent-like stems store water, and established plants withstand short dry periods without wilting. NC State Extension confirms they prefer moderately moist, well-drained soil but tolerate mild drought. This is a real advantage in raised beds that drain fast or terracotta containers that dry quickly in high heat. You will not lose a wax begonia to a long weekend away.
Dragon Wing begonias have similar moderate water needs but are larger plants with larger root systems — they dry out slower than walleriana in comparable containers, which makes them more forgiving in hot spells.
Size, Habit, and Design Fit
Standard wax begonias reach 6–12 inches tall (Clemson HGIC) — compact, tidy, and well-suited to borders, window boxes, and front-of-bed edging. Walleriana grows 10–18 inches in most conditions, spreading loosely and, in compact modern series like Super Elfin, staying near the lower end of that range.
Dragon Wing begonias are a different proposition: 24–36 inches tall with arching stems and large pendant flower clusters. For a half-barrel planter on a shaded patio, one Dragon Wing begonia fills the space that three walleriana would struggle to match. If architectural presence in a container is the goal, Dragon Wing is the stronger choice. For low edging and mass planting, wax begonias and standard walleriana both work — the begonia requires less upkeep.
Both plants are available in pink, red, salmon, white, and bicolor options. Impatiens walleriana offers slightly more variety in soft pastels and mixes; wax begonias come in a narrower palette but hold color without fading in warmer conditions. For a shade border combining multiple plants, either can anchor the foreground.
The Downy Mildew Problem Every Impatiens Grower Should Know
If you planted walleriana impatiens before 2012 and gradually stopped getting good results, downy mildew is almost certainly the cause — and it has likely persisted in your soil.
Plasmopara obducens is an oomycete (not a true fungus) that attacks Impatiens walleriana and garden balsam (I. balsamina) specifically. According to peer-reviewed research published in PMC, the epidemic spread to 33 US states by 2012 and to Hawaii by 2013, causing impatiens wholesale values to fall from approximately $150 million in 2005 to $65 million in 2015. Iowa State Extension confirms that no other annual hosts this pathogen — the disease is exclusive to impatiens species.
The mechanism is fast and visible: spores land on leaves, germinate in humid air, and colonize intercellular spaces. Symptoms begin as yellow stippling or downward leaf curl; within days, white fluffy sporulation appears on the undersides of leaves — visible without magnification. Defoliation follows within a week. There is no cure. Resting spores (oospores) persist in soil for up to 12 months, meaning planting walleriana in the same bed the following season restarts the cycle.
They look similar but grow very differently — begonia rex vs begonia maculata explains.
Three practical alternatives now offer near-direct substitutes while eliminating the IDM risk:
- SunPatiens (interspecific I. walleriana × I. hawkeri hybrid): 18–36 inches, shade to full sun, full IDM resistance, self-cleaning blooms from planting to frost
- Bounce impatiens (I. hybrida): mounding habit, 12–16 inches, IDM-resistant, closest visual match to traditional walleriana
- New Guinea impatiens (Impatiens hawkeri): larger individual flowers, higher light tolerance, full IDM resistance confirmed by Iowa State Extension
Begonias are never affected by this pathogen. If you have a history of IDM in a bed, switching to wax or Dragon Wing begonias eliminates the risk entirely while delivering comparable seasonal color.
Five Scenarios That Determine the Winner
The right choice depends on your specific conditions. Here is how the two plants compare in the situations most US gardeners actually face.
Scenario 1: Deep Shade Under a Deck or North-Facing Foundation
Winner: Walleriana impatiens (or Bounce if you have IDM history)
In genuine shade — under a deck, along a north-facing wall, beneath a dense canopy — walleriana outperforms begonias. Its photosynthetic efficiency in very low light is higher, producing denser color carpet at lower light levels than wax begonias, which reduce flower production and stretch toward any available light. If you can confirm no IDM history in the soil, walleriana still delivers the most consistent color in true shade. Use Bounce or SunPatiens if the soil has been infected previously.
Scenario 2: Deer Country
Winner: Wax or Dragon Wing begonias
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→ View My Garden CalendarImpatiens are a deer’s preferred meal. Wax begonias are deer and rabbit resistant — both Clemson HGIC and NC State Extension confirm this. The mild bitterness that browsers avoid in begonias makes them a practical choice for suburban beds that back up to wooded areas where seasonal deer pressure is high. No spray regimen is required. For a garden designed around long-season color with minimal intervention, this is a significant advantage.
Scenario 3: Household with Dogs or Cats
Winner: Impatiens (walleriana or New Guinea)
The ASPCA lists impatiens as non-toxic to dogs and cats. Begonias are toxic: they contain soluble calcium oxalates throughout the plant, with the highest concentration in the underground portions. Ingestion causes vomiting and salivation in dogs and cats; in horses, kidney failure is documented (ASPCA). If pets have access to your garden or patio containers, impatiens are the unambiguous safer choice. This is not a close call.
Scenario 4: Large Patio Container or Half-Barrel Planter
Winner: Dragon Wing begonia or SunPatiens Vigorous
Standard wax begonias (6–12 inches) and compact walleriana (10–18 inches) both look underwhelming in 20-inch or larger containers — the scale is wrong. Dragon Wing begonias reach 24–36 inches with pendant flower clusters on arching stems, filling large containers with real presence and remaining attractive from late May until frost. SunPatiens Vigorous series offers comparable size with the added advantage of sun tolerance if the container sits in a partly-sunny spot. For container gardening in shade or part shade, Dragon Wing is the most reliable large-scale choice.
Scenario 5: Budget Mass Planting (50+ Plants)
Winner: Wax begonias
Wax begonias are widely available, priced comparably to walleriana flat trays, and require less post-planting intervention. They need no deadheading, tolerate variable watering, resist deer, and hold up in heat better than walleriana in late summer. For large-scale seasonal color in a partly-shaded border where the goal is to plant once and maintain minimally, wax begonias deliver a better maintenance-to-result ratio than walleriana. The only caveat: they are toxic to pets.
Deer, Pets, and One Safety Note
Both toxicity and deer resistance deserve a direct summary since they affect purchasing decisions significantly.
Deer resistance: Begonias (wax and Dragon Wing types) are deer and rabbit resistant. Impatiens walleriana and New Guinea impatiens are not deer resistant — they will be eaten. If deer pressure is an issue in your area, begonias are the practical choice regardless of other factors.
Pet safety: Impatiens walleriana and New Guinea impatiens are non-toxic to dogs and cats (ASPCA confirmed). All begonias are toxic to dogs, cats, and horses due to soluble calcium oxalate content — the tubers and roots carry the highest concentration, but the entire plant is considered toxic. Symptoms in dogs and cats: vomiting, salivation, loss of appetite. If you have free-roaming pets, impatiens are the safer planting choice for shade beds and containers.
Overwintering: Both are grown as annuals in Zones 2–8. In Zones 9–11, wax begonias can survive as short-lived tender perennials if not hit by frost. Tuberous begonias (a separate category not covered here) can be dug and stored for winter. Standard walleriana and wax begonias offer no cold hardiness in northern gardens — plan to replant each spring.
Soil pH: Impatiens prefer pH 6.0–6.5 (UMN Extension); begonias prefer 5.5–6.5 (UMN Extension). In practice, the overlap is large and this distinction rarely matters unless your soil is strongly alkaline.
The Final Verdict
There is no universally better plant. The winner depends on your conditions:
| If you have… | Choose… |
|---|---|
| Deep shade, no IDM history in soil | Impatiens walleriana |
| IDM history or uncertain soil | SunPatiens or Bounce impatiens |
| Deer pressure | Wax begonias |
| Dogs or cats with garden access | Impatiens or New Guinea impatiens |
| Variable light (shade to part sun) | Bronze wax begonias or SunPatiens |
| Large containers on a shaded patio | Dragon Wing begonias |
| Budget mass planting, low maintenance | Wax begonias |
| Both sun and shade in same bed | SunPatiens (bridges both zones) |
One practical combination: plant wax begonias at the sunlit edges of a shaded border and Bounce or SunPatiens in the deepest shade zones. Both have similar water and soil requirements, so they can share a planting bed without conflicting care routines. For more on begonia variety selection, see the full guide to begonia types ranked by use.
Frequently Asked Questions
Can impatiens and begonias be planted together?
Yes. Both prefer well-drained, organically rich soil and similar watering schedules. The most effective combination puts walleriana in the deepest shade zones and wax or SunPatiens begonias at the sunnier edges — each plant gets the light level it performs best in. Avoid planting walleriana where it will receive afternoon sun as the season progresses.
Do begonias bloom as long as impatiens?
Both bloom continuously from planting until the first frost without deadheading. Wax begonias typically hold up better in the heat of late summer — impatiens walleriana can temporarily drop flower production during extended heat above 85°F, recovering when temperatures moderate. Begonias show less of this seasonal performance dip.
Are New Guinea impatiens the same as regular impatiens?
No. New Guinea impatiens (Impatiens hawkeri) is a different species from common garden impatiens (I. walleriana). New Guinea types have larger leaves, larger individual flowers, higher sun tolerance, and — critically — full resistance to the downy mildew disease that devastates walleriana. They are typically priced higher than standard impatiens but perform reliably in both shade and part-sun situations where walleriana would fail.
Why do my impatiens keep dying mid-summer?
Three causes account for most mid-season failures. First: downy mildew — check for white cottony coating on the undersides of leaves and yellowing at the canopy top. Second: afternoon sun — even three hours of direct afternoon sun scorches walleriana reliably in most US climates above Zone 6. Third: root rot from overwatering in poorly-drained soil, which presents as wilting despite wet soil. Match the diagnosis to the symptom before replanting.
Sources
- UMN Extension — Impatiens
- Clemson HGIC — Impatiens
- PMC — Comparative Analysis of Impatiens Leaf Transcriptomes (IDM resistance research)
- UMN Extension — Begonia
- NC State Extension — Begonia Wax Types
- Clemson HGIC — Begonia
- Iowa State Extension — Which Plants Are Susceptible to Impatiens Downy Mildew?
- ASPCA — Impatience Plant (Toxicity)
- ASPCA — Begonia (Toxicity)
