Raintree Growing Guide

Pollination & Pollinators

Self-fertile, self-sterile, triploid, parthenocarpic, dichogamous, wind-pollinated. The vocabulary alone is enough to leave new orchardists guessing. This guide gathers what every Raintree fruit guide references into one place — what each fruit needs, who actually moves the pollen, and what goes wrong when it doesn't.

The six things to know before you buy

Self-Fertile vs Not Some fruits set crops alone. Most apples, pears, sweet cherries do not.

Bloom Time Overlap Two compatible varieties don't help if they bloom weeks apart

Triploids Receive pollen but rarely give usable pollen — never your only pollenizer

Honeybees Aren't It Many fruits depend on native bees, flies, or wind — not honeybees

Pollinizer Distance Within 50–100 feet, fewer obstructions between, is the working rule

No Sprays at Bloom Insecticides during bloom kill pollinators — zero exceptions

Why pollination is the question that comes before every other question

Customers occasionally call Raintree the spring after their first harvest year, frustrated that the tree they bought is healthy, lush, and visibly thriving — but produced almost no fruit. The pruning was right. The site got plenty of sun. Water and fertilization were on schedule. And yet the tree sets almost nothing. The answer, more often than not, is pollination. The variety they bought is self-sterile, no compatible pollenizer is nearby, or the two trees that are nearby don't actually overlap in bloom. The mistake was made before the trees ever went in the ground.

Pollination is the answer to a question most new orchardists don't know to ask: "Will this plant actually fruit for me, given what else I'm planting?" Almost everything else — variety, rootstock, training system, pruning method — can be adjusted after planting if you change your mind. Pollination compatibility cannot. Two trees blooming three weeks apart will never pollinate each other no matter how well you prune them. A solo triploid apple will produce a handful of fruit a year forever.

This guide consolidates the pollination references scattered across every Raintree fruit guide. It starts with the vocabulary (which is more confusing than it should be), moves through who actually moves the pollen for each fruit type, lays out the bloom group system for apples and pears, and ends with the most common mistakes and how to avoid them.

ℹ Your fruit-specific guide is still the right detailed source

This guide covers the principles and provides a consolidated reference table. For variety-specific pollination details — exactly which apple pollinates which, which pluot pairs with which Japanese plum, which feijoa cultivars cross-pollinate — the individual fruit growing guides have the detail you need. Treat this guide as the framework; treat the per-fruit guides as the variety-level specifics.

The vocabulary — and why people mix it up

The terminology of pollination is genuinely confusing because several closely-spelled words mean different things. Before going further, here's the working vocabulary, in the order you'll most often encounter it.

Pollination

The act of moving pollen from anther to stigma

The transfer itself — whether by bee, fly, wind, or human hand. Without pollination, no fertilization, no fruit. Pollination is the process; the rest of the terms describe who does it, who needs what, and what counts as "compatible".

Pollinator

The animal (or wind) that does the moving

Bees, flies, beetles, hummingbirds, wind, and sometimes you with a paintbrush. Honeybees are famous, but native bees — mason bees especially — are dramatically more efficient pollinators of fruit trees per individual visit.

Pollenizer (or Pollinizer)

The plant providing the pollen

If your apple tree needs cross-pollination, the other variety that supplies the pollen is the pollenizer. (Note the spelling — pollen-izer, the one supplying pollen. The animal is the pollin-ator. Both spellings appear in the literature.)

Self-fertile (self-compatible)

Sets fruit from its own pollen

One plant alone produces a crop. Peaches, apricots, sour cherries, most figs, persimmons, pomegranates, and a handful of apples and pears (Granny Smith, Golden Delicious for example) fall here. Even most self-fertile fruits set better crops with a cross-pollenizer nearby.

Self-sterile (self-incompatible)

Cannot set fruit from its own pollen

Requires a pollenizer of a different variety, blooming at the same time, within pollinator-flight distance. Most apples, most European and Asian pears, sweet cherries, most Japanese plums and pluots, pawpaws, kiwis, hazelnuts, and blueberries (which set far better with cross-pollination).

Triploid

Receives pollen but gives little usable pollen

Has three sets of chromosomes instead of the standard two. Can set fruit when pollinated but produces few viable pollen grains itself. A triploid cannot serve as the pollenizer for other varieties. Plant triploids with two compatible diploid varieties — one to receive pollen, one to provide it to the third tree.

Parthenocarpic

Sets fruit without pollination at all

The plant develops fruit from unfertilized flowers; the fruit is usually seedless. Most fig varieties offered for the home garden are parthenocarpic. Babaco papaya, some persimmons, and a few other fruits are too. These need no pollenizer and no pollinator for fruit set.

Dichogamous (protogyny / protandry)

Male and female parts mature at different times

A flower-level strategy that prevents self-pollination on the same plant. Protogyny: female stage first, male after (pawpaw). Protandry: male first, female after (walnut, hazelnut). Practical effect: the pollen and the receptive stigma are rarely both ready at the same moment within a single tree, so cross-pollination from a different individual is critical.

Bloom group

A numerical bin for bloom timing

Used mostly for apples and pears (groups 1 through 5, early to late). Varieties in the same or adjacent groups bloom with enough overlap to pollinate each other. Varieties two groups apart often don't. The single most-overlooked factor in failed pollination.

⚠ "Self-fertile" doesn't always mean "single tree is best"

Many varieties listed as self-fertile produce a much heavier and more reliable crop with a cross-pollenizer nearby — apricots, sweet cherries marketed as self-fertile (Stella, Lapins), and most olives and feijoas all fall into this category. If space allows, a second compatible variety is almost always worth planting even when the first variety is technically self-fertile. UF/IFAS Extension's olive guidance (Publication ENH1254) is explicit that even self-fertile olive cultivars perform better with a pollenizer in many regions.

Who needs what — a fruit-by-fruit reference

This is the consolidated reference table from across every Raintree fruit guide. For variety-level detail (which specific Lapins pairs with which Bing, which pluot needs which Japanese plum), consult the per-fruit guide.

Fruit	Pollination type	Pollinator	Key notes
Apple	Mostly self-sterile	Bees (honey, mason, native)	Use bloom groups. Triploids exist (Gravenstein, Jonagold) — plant with two diploid partners. Crabapples are excellent pollenizers.
Pear (European)	Mostly self-sterile	Bees	Some self-fruitful exceptions. European and Asian pears generally do not cross-pollinate each other reliably.
Pear (Asian)	Mostly self-sterile	Bees	Plant two Asian pear varieties for reliable cross-pollination.
Peach / Nectarine	Mostly self-fertile	Bees	'J.H. Hale' is a notable exception requiring a pollenizer. Most others set well alone.
Apricot	Self-fertile	Bees	Most varieties self-fertile but yields improve with cross-pollination.
Plum (European)	Mostly self-fertile	Bees	Stanley, Italian Prune, Damson, Green Gage — all generally self-fertile.
Plum (Japanese)	Mostly self-sterile	Bees	Needs another Japanese plum or compatible pluot. European plums do not pollinate Japanese plums reliably.
Pluot	Self-sterile	Bees	Requires Japanese plum or another pluot of different variety. European plums will not serve.
Sweet cherry	Mostly self-sterile	Bees (heavy dependence)	Some self-fertile exceptions (Stella, Lapins, Sweetheart, Vandalay, Black Gold). Bing has incompatibility issues with Lambert and Napoleon.
Sour / pie cherry	Self-fertile	Bees	Montmorency and most pie cherries are self-fruitful. Don't rely on these to pollinate sweet cherries — bloom timing rarely overlaps.
Almond	Mostly self-sterile	Bees	'All-in-One' and 'Garden Prince' are self-fertile exceptions. Others need cross-pollenizers within ~100 feet, no solid barriers between.
Hazelnut / Filbert	Wind-pollinated	Wind (dichogamous)	Self-incompatible. Plant two compatible varieties — Raintree pollination charts list which combinations work. Pollination occurs in mid-winter.
Walnut	Wind-pollinated	Wind (dichogamous)	Protandrous — male flowers shed pollen before female flowers are receptive. Single tree often sets poorly; a second variety with offset timing improves set.
Chestnut	Wind-pollinated	Wind + some insects	Self-sterile. Plant two compatible varieties within 100 feet.
Pawpaw	Fly & beetle	Flies, beetles (not bees)	Protogynous flowers; self-incompatible. Plant two genetically distinct cultivars within 30–50 ft. Hand pollination strongly recommended.
Persimmon (American)	Mostly self-fertile	Bees	Female trees often set parthenocarpic (seedless) fruit alone. Male tree improves yield in some cultivars.
Persimmon (Asian)	Mostly self-fertile	Bees	Most popular varieties (Fuyu, Jiro, Hachiya) are self-fertile and parthenocarpic.
Quince	Self-fertile	Bees	Single tree reliably fruits.
Medlar	Self-fertile	Bees	Single tree fruits.
Fig	Parthenocarpic	None required	Raintree fig varieties are parthenocarpic — no pollinator needed, no pollenizer needed, no seeds.
Mulberry	Mostly self-fertile	Wind, some bees	Most named varieties self-fruitful. Some cultivars dioecious — confirm before buying.
Pomegranate	Self-fertile	Bees	Single plant fruits; multiple plants improve yield.
Olive	Wind + bees	Primarily wind	Most cultivars self-fertile; cross-pollination improves yield 10%+. Pollenizer within 50 ft. Manzanillo benefits significantly from Arbequina.
Blueberry	Cross improves yield	Bumblebees, mason bees	Many varieties listed as self-fertile, but all set much heavier crops with a different variety nearby. Bumblebees buzz-pollinate; honeybees less efficient.
Raspberry / Blackberry	Self-fertile	Bees	Single plant or cultivar fruits well.
Strawberry	Self-fertile	Bees	Self-fertile but pollinator visits improve fruit shape and size.
Currant / Gooseberry / Jostaberry	Mostly self-fertile	Bees	Most varieties self-fruitful.
Aronia / Elderberry / Serviceberry	Self-fertile	Bees, flies	Self-fruitful; multiple plants improve yield.
Honeyberry (Haskap)	Cross-pollination required	Bumblebees (cold-weather)	Two compatible varieties needed; blooms very early when honeybee activity is low — bumblebees are primary pollinators.
Goumi / Seaberry	Often needs partner	Bees	Goumi mostly self-fertile; Seaberry is dioecious — separate male and female plants required.
Kiwi (fuzzy & hardy)	Dioecious	Bees (need help in cool springs)	Separate male and female plants. One male pollinates up to 8 females. Hand pollination often needed in PNW cool springs.
Grape	Mostly self-fertile	Wind, some bees	Most table and wine grapes self-fertile. A few muscadines and wild grapes are dioecious.
Pineapple Guava (Feijoa)	Variety-dependent	Bees, birds	Named cultivars (Apollo, Coolidge, Gemini) partially self-fertile; cross-pollination dramatically improves yield. Seedlings often self-incompatible.
Loquat	Self-fertile	Bees	Most named varieties self-compatible.
Babaco Papaya	Parthenocarpic	None required	Sets fruit without pollination; no pollenizer needed.

ℹ The pattern, summarized

Most stone fruits (peach, plum, apricot, sour cherry) and most non-tree fruits (berries, currants, grapes) are self-fertile. Most pome fruits (apple, pear) and sweet cherries are self-sterile and need a compatible pollenizer. Nuts (hazelnut, walnut, chestnut) are wind-pollinated and need a different variety nearby. Pawpaw is fly-pollinated and almost always needs hand pollination for serious crops. Figs and babaco are parthenocarpic and need nothing.

Bloom groups — the apple and pear system

The most-skipped factor in self-sterile fruit pairings is the simplest: do the two varieties actually bloom at the same time? Two apple varieties three weeks apart in bloom share almost no overlap, no matter how compatible they are on paper. The bloom group system is a numerical shorthand for matching bloom times across varieties.

How bloom groups work

Each variety is assigned a bloom group from 1 (early) to 5 (late). A variety reliably pollinates other varieties in its own group and in the groups immediately before and after. Varieties two or more groups apart usually don't share enough bloom overlap for reliable pollination.

1 Early Works with 1, 2

2 Early-Mid Works with 1, 2, 3

3 Mid Works with 2, 3, 4

4 Mid-Late Works with 3, 4, 5

5 Late Works with 4, 5

Triploids — the asterisk in the system

Some popular apple varieties are triploids: Gravenstein, Jonagold, Mutsu (Crispin), Bramley's Seedling, Winesap, Stayman, Spigold, Roxbury Russet, Belle de Boskoop, and several others. Triploids receive pollen and set fruit normally, but produce little usable pollen of their own. A triploid cannot serve as the pollenizer for other varieties.

If you want to plant a triploid, the rule is: plant two compatible diploid varieties along with it. The triploid receives pollen from both diploids. The two diploids pollinate each other and the triploid. A solo triploid will set some fruit if there is a compatible variety in a neighbor's yard within bee-flight distance, but it cannot be relied upon to pollinate anything else.

⚠ Gravenstein bloom group — verify before planting

Gravenstein is listed in Group 1 in many North American sources, but European references commonly place it in Group 3. Because Gravenstein is also a triploid (poor pollen donor), pairing it incorrectly can leave an entire orchard without pollination. If you are planting Gravenstein, confirm its bloom group with your nursery before selecting companions, and provide two diploid partners spanning the likely range (Group 2 and Group 3 varieties) to be safe.

Crabapples — the universal pollenizer

A crabapple in or near the orchard is one of the most reliable solutions to apple pollination. Crabapples are diploid (good pollen donors), bloom over a long window that overlaps most named apple varieties, and produce abundant pollen. A single ornamental crabapple within 50–100 feet of a planting can pollinate a small orchard's worth of named apple varieties.

Cultivars specifically promoted as orchard pollenizers (Manchurian crab, Snowdrift, Whitney crab, Centurion) are widely available. Even purely ornamental crabapples in the neighborhood will usually do the job if their bloom overlaps your apples.

For pears — same idea, slightly different groupings

European pears use a similar bloom-group system but the groupings are simpler — most modern European pear varieties bloom within a fairly tight window and most popular varieties cross-pollinate freely. The main caution is that European and Asian pears generally do not cross-pollinate each other reliably, despite their close relation. Plant a second European pear to pollinate a European pear; plant a second Asian pear to pollinate an Asian pear.

The pollinators — who actually moves the pollen

The pollinator is the animal (or process) that physically carries pollen from one flower to another. Different fruits depend on different pollinators, and "we'll just rely on honeybees" — the default assumption of many new orchardists — is wrong for a surprising number of crops. Understanding which pollinator your fruit depends on changes how you manage the orchard, what you plant alongside, and when you absolutely must not spray.

European honeybees

Pollinates: most fruit trees, berries, grapes

The most famous pollinator and the workhorse of commercial fruit production. Honeybees are generalists — they work most blooms, communicate with hivemates about flower locations, and can be relocated as managed colonies for orchard-scale pollination.

Don't fly well below 55°F or in steady rain
Less efficient than mason bees on a per-bee basis for most stone and pome fruits
Heavily dependent on managed beekeeping in many regions
Honeybee populations have declined in many areas; native pollinators matter more than ever

Mason bees (Osmia)

Pollinates: apples, pears, cherries, plums, peaches, blueberries

Native solitary bees that are arguably the best pollinator for temperate fruit trees — particularly in the PNW where they evolved alongside native fruits and where the cool, wet spring weather grounds honeybees but mason bees still fly.

Fly at 50–55°F when honeybees stay in the hive
One female mason bee pollinates as many flowers as 60–100 honeybees per visit (USDA, Xerces Society)
Active only in spring during fruit-tree bloom — exactly when needed
Solitary, non-aggressive, don't sting unless handled directly
Easy to support with a simple bee house and access to mud

Bumblebees

Pollinates: blueberries, honeyberries, cranberries, kiwifruit

Large native bees that work in colder, wetter, dimmer conditions than honeybees and perform a specialized technique called buzz pollination (sonication) that's essential for blueberries and some other Ericaceae.

Fly at temperatures honeybees can't (down to 40°F)
Buzz pollination shakes pollen loose from the closed anthers of blueberry flowers — honeybees can't do this
Critical for early-bloomers like honeyberry that bloom before honeybee colonies are fully active
Support with continuous bloom from early spring through fall

Native solitary bees (other)

Pollinates: nearly all flowering fruit

Beyond mason bees and bumblebees, North America has roughly 4,000 native bee species — leafcutter bees, mining bees, sweat bees, polyester bees, and many others. Most are solitary, most don't sting, and collectively they're the most important pollinators for many fruit crops in unmanaged landscapes.

Each species has its own seasonal window, body size, and preferred flowers
Many nest in bare ground, leaf litter, or hollow stems — habitat matters as much as flowers
Xerces Society publishes excellent free guides on supporting native bees by region

Flies and beetles

Pollinates: pawpaw (essential), some early-spring fruit

The forgotten pollinators. Carrion flies and beetles are the primary pollinators of pawpaw, with its rot-scented maroon flowers. Hover flies and other flies pollinate many spring-blooming fruits in cool conditions where bees are scarce.

Pawpaw flowers are specifically adapted to fly pollinators — bees largely ignore them
Some growers hang small bait (raw meat, fish scraps) near pawpaw trees during bloom
Hover flies are also valuable aphid predators — supporting them benefits the orchard in two ways
Hand pollination is strongly recommended for pawpaw regardless of fly populations

Wind

Pollinates: hazelnut, walnut, chestnut, mulberry, olive, grape

The pollinator that doesn't need attracting. Nut trees and several fruit species have evolved to release pollen into the air and rely on wind to carry it. Wind-pollinated species typically have inconspicuous flowers (no need for petals to attract animals) and produce massive quantities of pollen.

Trees must be within wind-carry range — typically 50–100 ft, with no solid wind barriers between
Hazelnuts pollinate in mid-winter — pollen sheds from male catkins December through February depending on cultivar and region
Wind-pollinated species are usually dichogamous — male and female parts mature at different times within a single tree
A single tree often sets poorly even when "self-fertile" — a second variety with offset timing always improves results

Hummingbirds and other birds

Pollinates: feijoa (significantly), some others

Less common than insects but real. Hummingbirds work feijoa (pineapple guava) flowers actively — they pull the edible petals off to access nectar, transferring pollen between flowers in the process. Some tropical fruits depend heavily on bird pollination.

The fleshy edible feijoa petals are an evolutionary trade-off: birds eat them, birds visit, pollination happens
Encourage hummingbirds with flowering shrubs and feeders if you grow feijoa

Hand pollination (you)

Pollinates: anything natural pollinators don't

A small artist's paintbrush or cotton swab transferring pollen between flowers. Useful for pawpaw (where natural pollination is unreliable), kiwi (in cool springs when bees are scarce), feijoa in cool springs, and any time you have a single tree of a self-sterile variety and no compatible partner is blooming nearby.

Work in mid-morning after dew has dried but before midday heat
Touch the brush to a pollen-shedding anther, then to several receptive stigmas on other flowers
For some species (pawpaw especially), recognizing which flowers are in the male vs. female stage is the entire trick

Mason bees — the home orchardist's best ally

If you grow fruit trees in the temperate U.S. — and especially in the Pacific Northwest — mason bees deserve a section of their own. They are the single highest-leverage thing you can add to a home orchard to improve pollination, they cost almost nothing to support, and they work in weather honeybees can't.

What makes them different

The blue orchard mason bee (Osmia lignaria) is native to North America and evolved with native fruit trees. It is solitary (each female nests alone), non-aggressive (males have no stingers; females sting only if physically restrained), and astonishingly efficient. Research published by USDA and the Xerces Society finds that a single female mason bee pollinates as many flowers in a day as 60–100 honeybees — partly because they fly in conditions honeybees won't, partly because they make more flower visits per bee, and partly because their belly-carrying technique distributes pollen more thoroughly than honeybees' leg-pollen-pellet method.

Mason bees are active in spring only — emerging from their cocoons in March or April just as fruit trees begin to bloom, working hard for 4–6 weeks, and then completing their life cycle and sealing the next generation into nest cells by early summer. The cocoons overwinter in the nest and emerge the next spring. The timing is a near-perfect match to fruit tree bloom in most of North America.

Mason bee nest house basics

A mason bee nest provides cavities of the right size (5/16" diameter, 6–8" deep). Paper tubes or hollow reed sections work; sealed entries indicate completed nest cells with developing larvae.

Supporting mason bees — what they actually need

Nest cavities of the right size. 5/16" diameter (8mm) tubes, 6–8" deep. Paper tubes, hollow reed sections, drilled wood blocks, or commercial mason bee houses all work. Avoid plastic tubes that don't breathe — fungal problems develop in plastic.
The right location. Mount the house facing southeast at 4–6 feet above ground. Morning sun warms the bees and gets them flying early; afternoon shade prevents overheating. Sheltered from direct rain, fixed firmly so it doesn't sway in wind.
Mud. Mason bees use mud to seal each nest cell — without a mud source within about 50 feet of the nest house, females spend too much energy commuting and lay fewer eggs. A shallow dish of mud kept moist, or a permanent damp clay-soil area, is essential.
Flowers in bloom during their flight period. Early-blooming fruits (cherries, plums, peaches) and spring native flowers feed the bees while your apple and pear are still in tight bud. Mason bees emerge in March or April depending on region; they need food on day one.
Cocoon management (optional but helpful). Hobbyist mason bee keepers harvest cocoons in fall, clean them gently, and store them cool over winter. This breaks the pest-and-disease cycle (mites, parasitic wasps) that builds up in nest tubes left untended for multiple years. Crown Bees and other suppliers publish detailed instructions.

Pacific Northwest tip

The blue orchard mason bee (Osmia lignaria propinqua— the western subspecies) is native to the PNW and evolved with our cool, wet springs. They are dramatically more effective than honeybees here for the same reason honeybees struggle: the weather. WSU Extension and OSU Extension both publish mason bee guides specific to the region. If you grow apples, pears, or cherries west of the Cascades and you do not currently have mason bees on your property, this is the highest-leverage single thing you can add to your orchard — substantially higher impact than any other pollination intervention.

A bee-friendly orchard — practices that pay back

Supporting pollinators is not a moral exercise — it's a practical one. An orchard with strong native bee populations sets heavier and more reliable crops, year over year, than an orchard that relies entirely on whatever honeybees happen to be working that day. The Xerces Society, USDA NRCS, and most state extension services publish guidance that converges on the same core practices.

Pesticide timing — the single biggest lever

Insecticides applied during bloom kill the pollinators that are visiting your flowers. This is true of every insecticide — synthetic, organic, OMRI-listed, "bee-safe-with-restrictions" — at the moment of application. Even fungicides commonly applied at bloom can be harmful to bees in some combinations. The rule that holds across every extension recommendation is identical: do not spray during bloom. Period. If a problem is severe enough to require intervention during bloom, the right answer is to delay until petal fall, accept the year's losses, or contact an extension agent for a specific exception.

⚠ "Bee-safe" insecticides are not actually bee-safe at bloom

Products marketed as gentler to pollinators — including spinosad, pyrethrins from natural sources, neem oil at high concentrations, and most "organic" insecticides — can still kill bees that contact the wet spray or treated flowers. Bee safety with these products comes from timing, not from inherent harmlessness: apply early morning before bees are active, in late evening after foraging ends, and only outside of bloom periods. The OSU PNW Pest Management Handbook is explicit on this point. There are no insecticides safe to spray onto open blooms with bees actively working.

Plant a continuous bloom sequence

Native bees and other pollinators need food across the full season, not just during fruit tree bloom. Plantings that include early-blooming, mid-season, and late-blooming flowers support pollinator populations through their full life cycles — which means more pollinators in your orchard next spring.

Early spring — willow, hazelnut catkins, crocus, native plums, dandelion (leave some), red maple, pussy willow
Spring — fruit trees in bloom, serviceberry, native cherries, comfrey, borage, phacelia
Early summer — raspberry, blackberry, white clover, lavender, native asters beginning to leaf
Midsummer — sunflowers, oregano in bloom, summer phlox, mountain mint, lavender (continuing)
Late summer / fall — native asters, goldenrod, sedum 'Autumn Joy', echinacea, late lavender

The Xerces Society maintains regional plant lists (xerces.org) tailored to each U.S. region. Their PNW pollinator plant list is particularly thorough.

Habitat structure matters as much as flowers

Bare ground patches — many native bees nest in soil; preserve sunny, unmulched areas for them to dig
Hollow stems and snags — leave dead stems standing through winter rather than cutting back in fall; many native bees overwinter in them
Brush piles and edges — provide overwintering habitat for bumblebees and other native pollinators
Water source — a shallow dish with rocks for landing, kept refreshed, gives bees a drinking station

What not to do

Don't spray broad-spectrum insecticides without a clear pest reason and outside of bloom
Don't apply neonicotinoid soil drenches to fruit trees — the pesticide is translocated into pollen and persists for years
Don't manicure every corner of the property — pollinators need messy edges, fallen wood, weedy strips
Don't rely entirely on managed honeybee hives for pollination if native bees can do the job — diversity outperforms dependence

Hand pollination — when, how, and for what

Hand pollination — moving pollen between flowers with a small brush, cotton swab, or paintbrush — is the backup plan when natural pollination is unreliable. For a few fruits, it's not optional but expected. For others, it's a useful intervention in cool springs when bee activity is low.

The technique

Pick the right time — mid-morning after dew has dried but before the day's heat. Flowers are open, pollen is dry and dustable, and stigmas are receptive.
Identify donor and receiver flowers — pollen comes from anthers showing loose dusty pollen; stigmas are receptive when shiny and slightly sticky. For dichogamous species (pawpaw, walnut), distinguish male-stage from female-stage flowers (see below).
Transfer the pollen — touch a small soft brush or cotton swab to a pollen-shedding anther, then to several receptive stigmas. Move between donor flowers as needed to keep the brush dusted with pollen.
Mark or count the work — for hobbyist record-keeping, marking pollinated flowers with a tie of yarn or a small flag lets you confirm fruit set later.

When hand pollination is essential

Pawpaw — the most common case. Pawpaw's fly pollinators are unreliable, the flowers are protogynous (female stage first, male after), and most home orchardists who get serious crops do so by hand pollination. Recognize female-stage flowers (shiny, sticky stigma, no loose pollen visible) and transfer pollen from male-stage flowers (anthers brown and dusty) on a different cultivar.
Kiwifruit in cool springs — when bees aren't flying during kiwi bloom (common in maritime PNW), hand pollination from a male vine to female vines can rescue an otherwise lost season.
Feijoa / pineapple guava in cool springs — similar logic. Edible flower petals fall after pollination; if petals stay intact, pollination didn't happen and intervention may help.
Self-sterile fruit with no nearby pollenizer — if you have a single self-sterile tree (a Bing cherry, for example) and the neighbor's pollenizer is dropping off, gathering pollen from a different variety at a different site and bringing it to your tree on a brush is the last-resort option.

When hand pollination doesn't help

Wind-pollinated species (hazelnut, walnut, chestnut) — the bloom is too dispersed and pollen too plentiful for meaningful hand pollination. The fix is planting a compatible second variety, not brushwork.
Triploid varieties — hand pollination of a triploid still requires viable pollen from a diploid donor. Triploid pollen is the problem; hand pollination doesn't solve it.
Frost-damaged flowers — if a late frost has damaged blossoms, the ovaries are dead and no amount of pollen application will set fruit. Inspect flowers after a frost event before deciding whether to intervene.

What goes wrong — the common failure modes

When a customer calls Raintree about poor fruit set, the answer is almost always one of the following six causes. Going through them in order helps diagnose what happened.

No pollenizer planted. The single most common cause. A self-sterile variety was planted alone with no compatible partner within bee-flight distance. The tree will set a token crop in some years (when a neighbor's tree happens to bloom in range) and almost nothing in others. The fix: plant a compatible variety, or use a graft to add a pollenizer branch to the existing tree.
Bloom-time mismatch. Two varieties were planted, but they bloom at different times. Group 1 apple paired with Group 5 apple share almost no bloom overlap; even Group 1 with Group 3 may overlap insufficiently in cool springs. The fix: confirm bloom group compatibility before planting; add a third variety in an intermediate group if existing trees don't overlap.
Triploid as solo pollenizer. A Gravenstein or Jonagold planted alongside another variety, with the assumption the triploid would pollinate the second tree. Triploids receive but don't reliably donate. The fix: plant two compatible diploid varieties along with the triploid.
Frost during bloom. A late spring frost killed open flowers or unopened buds, destroying the year's crop regardless of pollination management. The fix: site selection (avoid frost pockets), variety selection (later-blooming varieties in frost-prone regions), and physical protection (overhead irrigation during freeze events, frost cloth on small trees) all reduce risk.
Pollinator failure — wrong weather or no pollinators. Cool, rainy, or windy weather during bloom grounds honeybees and limits even mason bee activity. A year with poor weather at bloom can produce a poor crop on otherwise correctly-planted trees. The fix: support multiple pollinator types so weather conditions matching some of them is more likely; mason bees particularly help in PNW cool springs.
Pesticide drift or in-orchard application during bloom. Insecticides applied during bloom — yours, a neighbor's, or a county spray program's — kill pollinators directly. Spring orchard insecticide applications are a common cause of mysterious fruit-set failures. The fix: time your own sprays outside of bloom, talk to neighbors about timing if necessary, and contact local extension if county-level applications are affecting your trees.

ℹ Diagnosing a poor-fruit-set year

Walk the orchard the week after petal fall and look at the small developing ovaries (the swelling at the base of where the petals were). Pollinated flowers swell visibly within a week of bloom; unpollinated ones drop off or shrivel. If a tree had visible bloom but nothing has swollen ten days later, pollination failed. If swollen ovaries are present but later drop ("June drop"), the trees pollinated but are now self-thinning the crop — this is normal and the harvest will still produce. Diagnosing the failure mode shapes what to do next year.

Quick reference — the planting-day decisions

If you're standing at the catalog page deciding what to buy, this is the short version of everything above:

If buying a self-sterile fruit (most apples, pears, sweet cherries, Japanese plums, pluots, pawpaws, kiwis, hazelnuts, walnuts) — buy two compatible varieties from the start, or confirm a compatible pollenizer is on a neighboring property within 100 feet.
If buying a triploid apple variety (Gravenstein, Jonagold, Mutsu, Winesap, Stayman, Belle de Boskoop, etc.) — buy two compatible diploids along with it. The triploid receives; the diploids pollinate each other and the triploid.
If buying a kiwi — buy one male for every 6–8 females of the same species, in the same general planting area.
If buying a seaberry — buy at least one named male variety for every several female plants (seaberry is dioecious).
If buying a pawpaw — buy two genetically distinct named cultivars, plant them within 30 feet, and plan to hand-pollinate for serious crops.
If buying a self-fertile fruit and have space for a second tree — plant a different variety anyway. Cross-pollination almost always improves yield on self-fertile fruit, even when not strictly required.
If you have no other pollinators on your site — install a mason bee house at planting. The bees will find their own way; the nest gives them somewhere to settle.
Always — plan your spray program around bloom. Insecticides during bloom defeat the entire pollination effort regardless of how well-matched your varieties are.