Raintree Growing Guide
Mulberries
One of the oldest cultivated fruits in the world — extraordinarily productive, low-maintenance, and capable of feeding a family from a single tree. The challenge isn't growing mulberries; it's deciding what to do with the abundance.
AT A GLANCE
SUN
6–8 hours minimum; full sun produces best yields and fruit quality
USDA ZONES
4–8 for most; some varieties tolerate Zone 9–10
Soil pH
6.3–6.8; tolerates a wide range of soils provided drainage is adequate
Pollination
Self-fertile and wind-pollinated; a second tree improves yield and size
First Fruit
Grafted trees: 2–3 years; seedling trees: up to 10 years — buy grafted
Mature Size
Grafted: maintainable at 6 ft; unpruned to 25–30 ft; Gerardi dwarf: 6–8 ft
Chill Hours
Low requirement: ~100–400 hrs depending on species; highly adaptable
Growing difficulty
Easy — vigorous and self-fertile
Caution
Do not plant near water lines or septic systems — aggressive water-seekers
Why grow mulberries?
Mulberries (Morus species) are among the oldest cultivated fruits in the world — grown in Asia for silkworm culture for millennia, and valued for their fruit across cultures from China to Persia to the eastern United States. For the home gardener, they represent one of the best value propositions in the fruit tree world: low maintenance, extraordinary productivity, wide climate adaptability, and fruit that is virtually unavailable commercially because it is far too delicate to ship.
A mature mulberry tree in full production can yield more fruit than most families can process — the abundance is one of the defining characteristics of the plant. Fresh mulberries are sweet, richly flavored, and deeply colored; they make exceptional jam, wine, juice, and baked goods, and freeze well for long-term storage. The fruit does not keep long at room temperature and bruises easily, which is exactly why grocery stores don't carry it — and exactly why a home-grown mulberry is a revelation to anyone who has only encountered them as an ingredient rather than a fresh fruit.
Beyond fruit, mulberries are handsome, fast-growing shade trees with attractive lobed foliage. They are adaptable to a wide range of soils, are relatively drought-tolerant once established, and have few serious pest or disease problems. If there is a single caution it is this: do not plant mulberry trees near water lines, irrigation pipes, or septic systems. Mulberries are aggressive water-seekers and their roots will pursue and infiltrate any underground water source they can reach. Site selection with this in mind is the most important pre-planting decision you will make.
The three main species
Mulberries sold for fruit production come from three primary species, each with distinct characteristics, cold hardiness, and flavor profiles. Understanding which species you are buying matters — particularly for cold-climate growers.
White Mulberry — Morus alba
Native to China; the species originally cultivated for silkworm culture. Extremely hardy and adaptable — tolerates temperatures to −25°F (Zone 4) and grows in poor soils, drought, and urban conditions. Fruit ranges from white to lavender to black depending on variety; flavor is mild and sweet, less complex than black mulberry. Ripens early, often before SWD pressure peaks. Most widely adapted for US home growing. The species name refers to the fruit color of the original Chinese types, not all cultivars. Chill hours: approximately 300–500.
Black Mulberry — Morus nigra
Native to western Asia; widely considered to have the finest fruit of the three species — deeply flavorful, rich, sweet-tart, with a complex flavor profile. Slower-growing and less cold-hardy than white or red mulberry; damaged below 0°F and best suited to Zones 6–9. More susceptible to leaf disease in wet climates. Named for its large dark buds, not necessarily the fruit color — though fruit is typically very dark. Lower chill hours than white mulberry; approximately 200 hours or less. Worth the extra site care for the flavor.
Red Mulberry — Morus rubra
Native to the eastern and central United States — the only mulberry species native to North America. Hardy and shade-tolerant; more suited to the cool, moist understory conditions of eastern woodlands than to hot, dry exposites. Fruit is deep red to black at maturity; good flavor, often compared to blackberries. Less commonly sold as named cultivars than white mulberry; most commercial red mulberry planting is done with hybrids. Chill hour requirement variable and not well established; generally low.
💡 Species names vs. fruit color
The common names "white," "red," and "black" mulberry refer to the species, not reliably to the fruit color. Morus alba(white mulberry) produces fruit ranging from white to lavender to nearly black depending on the variety. Morus rubra(red mulberry) produces dark red to black fruit. Morus nigra(black mulberry) produces consistently dark, richly colored fruit. When selecting a variety, look at the cultivar description rather than the species name for expected fruit color.
Pacific Northwest tip
White mulberry varieties and hybrids perform best in the PNW — they tolerate the region's variable conditions and ripen reliably even in cooler summers. Black mulberry (M. nigra) can be grown in the warmest PNW locations (Willamette Valley, southern Oregon) but is susceptible to leaf disease in persistently wet conditions and may be marginal in cold-winter inland sites. Red mulberry is rarely sold as a named cultivar but performs well as a shade tree in the cooler, moister parts of the region. Illinois Everbearing (a white × red hybrid) is among the most commonly planted and highly regarded varieties for the PNW home garden.
Site selection and planting
The pipe and septic warning — site first
Before selecting a planting location, map the location of all underground water lines, irrigation pipes, drainfields, and septic system components on your property. Mulberry roots actively seek water and will infiltrate any underground water source within reach. Root intrusion into pipes or septic systems is expensive to remediate and can cause serious damage. Maintain a minimum distance of 25–50 feet from any underground water infrastructure — further if your soil is sandy or the trees are in a particularly dry location where roots will range more aggressively.
Sun
Mulberries need 6–8 hours of direct sun daily for best fruit production and flavor development. They will grow in partial shade but fruit set, flavor, and quantity all decline with reduced light. In hot-summer climates, some afternoon shade is acceptable; in the PNW's cooler, cloud-influenced summers, full sun is strongly preferred.
Soil
Mulberries are among the most soil-tolerant fruit trees available — they will grow in clay, loam, sandy, or rocky soils provided drainage is adequate. They are not reliably drought-tolerant when young, however, and are notably thirsty trees compared to most fruit species. Target a pH of 6.3–6.8. Improve the planting area by working 1–2 inches of compost or organic matter into a zone 1.5–2 times the diameter of the planting hole and up to a foot deep. A 2–4 inch mulch layer applied after planting conserves moisture, moderates root-zone temperature, and feeds soil biology as it breaks down.
Buy grafted, not seedling
This deserves emphasis: always purchase grafted mulberry trees for fruit production. Mulberry trees grown from seed take approximately 10 years to begin fruiting. Grafted trees from named cultivars begin producing in 2–3 years. Raintree sells grafted trees; if you encounter an ungrafted seedling mulberry being sold for fruit, reconsider — you may wait a decade for your first berry.
Planting
Plant in early spring in most climates — container-grown trees can go in at any point during the growing season with adequate irrigation. Dig a hole at least twice the diameter of the root ball. Backfill with amended native soil; do not add fertilizer directly to the planting hole. Set the tree at the same depth as it was in the container. Water thoroughly and apply mulch immediately, keeping it 4–6 inches back from the trunk to prevent rot and discourage voles.
Pacific Northwest tip
Mulberries are notably water-hungry during establishment — more so than most other fruit trees. In the PNW, spring rainfall typically covers the first season adequately west of the Cascades, but supplemental irrigation during dry July through September periods is important in the first and second years. East of the Cascades, plan for consistent irrigation from planting through the end of the first growing season. Once fully established (typically by year 3), mulberries in the maritime PNW need little supplemental water except in drought years.
Pollination
Mulberry trees are self-fertile and wind-pollinated — a single tree will set fruit without a pollinizer and without relying on bees or other insects. This makes them uniquely useful in situations where pollinator activity is unreliable, such as early-season fruiting in cold springs, or in urban locations with limited insect access.
However, as with most self-fertile plants, a second tree of a compatible variety planted within 50 feet will meaningfully increase fruit size and harvest volume. Cross-pollination between trees of the same species produces larger, better-filled fruit. If space allows, two trees are substantially more productive than one. Two trees also stagger ripening slightly, extending the harvest window.
Mulberry trees can be monoecious (male and female flowers on the same tree) or dioecious (separate male and female trees). Most cultivated varieties sold for fruit production are monoecious and self-fertile. Confirm the pollination type when purchasing — a purely male tree will produce no fruit, and a purely female tree in isolation will produce fruit but will set better with a male nearby.
Chill hours
Mulberries have one of the lowest chill hour requirements of any commonly grown deciduous fruit tree — a significant advantage for gardeners in mild-winter climates. Chill hours are the cumulative hours between 32°F and 45°F that a plant needs during winter dormancy to break dormancy uniformly and fruit reliably in spring.
Requirements vary by species:
- Morus alba (white mulberry): approximately 300–500 hours; adaptable to a wide range of winter climates
- Morus nigra (black mulberry): approximately 200 hours or less; suited to mild-winter climates including parts of California and the warmer PNW
- Morus rubra (red mulberry): chill hour requirement variable and not well established; generally low
In most of the continental US, mulberries receive more than adequate chill hours without concern. Growers in the warmest parts of California, the Gulf Coast, or Florida should confirm variety-specific chill requirements against their local chill hours before selecting. Your local cooperative extension service can help determine typical chill hours for your location.
One important note on chill hours and late-spring frost: mulberries tend to leaf out relatively early in spring, and new growth can be damaged by late frosts. Unlike the chill hour problem (insufficient cold), this is a frost-timing problem — the tree has completed dormancy and starts growing before the last frost date. Selecting a site with good cold air drainage and avoiding frost pockets reduces this risk.
Choosing varieties
Named mulberry cultivars differ in fruit size, color, flavor, ripening time, and tree size. The following are widely grown varieties well-suited to home gardens; Raintree's catalog includes current availability. For PNW growers, prioritize varieties with proven performance in the maritime climate — Illinois Everbearing in particular has an exceptional track record.
| Variety | Species | Fruit | Notes |
|---|---|---|---|
| Illinois Everbearing | Hybrid | Black; large | The most widely recommended home garden mulberry in the US. A white × red mulberry hybrid combining cold hardiness with excellent fruit quality. Ripens over an extended season (hence "everbearing") from early to late summer rather than all at once — a major advantage for home use. Large, flavorful black fruit; vigorous tree. Widely adapted; excellent PNW performer. Zones 4–8. Self-fertile. |
| Pakistan | M. alba | Dark red; very long | Distinctive fruit — elongated to 3–5 inches, resembling a very large blackberry. Exceptionally sweet; excellent fresh eating. Low chill requirement (~200 hrs) suits mild-winter climates. Less cold-hardy than Illinois Everbearing; best in Zones 7–10. Late-ripening, which increases SWD exposure in the PNW — plan monitoring accordingly. A conversation piece in the garden. |
| Oscar | Hybrid | Black; large | Large, very sweet fruit with good flavor. Vigorous tree; productive. Good cold hardiness. A reliable choice where a large, standard-sized tree is appropriate. Zones 5–8. |
| Kokuso Korean | M. alba | Black; medium | Korean selection known for early ripening — often the first mulberry of the season — and reliable cold hardiness. Good flavor; productive. Early ripening reduces SWD exposure. A good anchor for the early end of a staggered mulberry harvest. Zones 4–8. |
| Wellington | M. rubra | Dark red–black; large | One of the few widely available red mulberry selections. Large, flavorful fruit with a blackberry-like quality. Ripens mid-season. More shade-tolerant than white mulberry. Good cold hardiness. Zones 5–8. |
Pruning and training
Mulberries require less annual pruning than most other fruit trees. Left unpruned, grafted trees will grow to 25–30 feet over many years — large and productive, but difficult to harvest and eventually requiring a ladder for any fruit. Most home gardeners prune to maintain a manageable height of 8–15 feet. Gerardi Dwarf varieties naturally stay compact and need minimal pruning.
Prune during dormancy — late winter before bud break is the ideal window. Mulberries bleed sap heavily when cut while actively growing; dormant-season pruning minimizes this. The goal is an open canopy with good light penetration and a framework of well-spaced scaffold branches. Remove any crossing, crowded, or dead branches. Head back the central leader or tallest branches to the desired height, cutting to an outward-facing bud.
Fruit is produced on short spurs along the branches — avoid removing too much spur-bearing wood. A light annual thinning of the canopy is generally more productive than heavy pruning every few years. Young trees benefit from early training to establish a strong framework; after the framework is set, maintenance pruning is minimal.
⚠Mulberries stain — plan accordingly
Ripe mulberries stain everything they touch: hands, clothing, concrete, decking, and car paint. Situating the tree where dropped fruit falls on grass or a mulched area rather than hardscape saves considerable frustration. A sheet or tarp spread under the tree and shaken periodically is the easiest harvesting method for ripe fruit — mulberries that are truly ripe will drop with minimal effort. Wear clothes you don't mind staining during harvest season.
Pacific Northwest tip
WSU Extension notes that mulberries in the PNW benefit from pruning to an open vase or modified central leader form that maximizes light penetration — particularly important west of the Cascades where overcast conditions are common. Keeping trees at a harvestable height (10–15 feet) also allows harvesting ahead of the birds, who will arrive reliably the moment fruit begins to ripen. A maintained, accessible tree is a harvested tree; a 30-foot unpruned tree feeds the neighborhood wildlife.
Watering and feeding
Mulberries are notably thirsty trees — more water-demanding than most other fruit species, particularly during establishment and fruit development. The general guideline of 1 inch of water per week applies, but mulberries often benefit from more frequent watering in the first 1–2 years while the root system is developing. Apply water deeply and less frequently rather than lightly every day — deep watering encourages roots to follow moisture downward rather than staying shallow. In hotter, drier climates, deep watering twice per week during establishment is appropriate.
Once established — typically by year 3 — mulberries in the PNW and other regions with meaningful summer rainfall need relatively little supplemental irrigation. In drier climates (eastern WA and OR, California, the Southwest), plan for consistent summer irrigation throughout the tree's life. Mulch generously to conserve moisture at the root zone; a 3–4 inch layer of wood chips or straw maintained year-round makes a meaningful difference in water retention, especially in the critical first growing seasons.
Fertilize conservatively. A couple of inches of well-rotted compost applied over the root zone each spring provides adequate fertility for most established trees. A balanced all-purpose fertilizer can be applied in early spring if the tree shows signs of deficiency (pale foliage, minimal growth). Avoid fertilizing after early summer — late-season nitrogen encourages soft new growth susceptible to cold damage. A tree producing a foot or more of new growth per year with healthy foliage likely needs no additional fertilizer.
Harvest
Mulberries do not ripen all at once — most varieties ripen over a period of several weeks, which is both a blessing (extended harvest window) and a management consideration (requires regular attention). Fruit is ripe when it is deeply colored, slightly soft to the touch, and detaches from the stem with the lightest pressure or drops on its own. Unripe mulberries are astringent and unpleasant — the color change from red to deep purple-black on most varieties is a reliable visual indicator, but taste is the most accurate test.
The easiest harvesting method for a well-pruned tree is to spread a tarp or old bedsheet under the canopy and gently shake the branches — ripe fruit will fall freely. Collect and process the same day; mulberries do not keep at room temperature for more than a day or two. Refrigerate immediately after harvest and use within 2–3 days, or freeze for long-term storage. Mulberries freeze beautifully — spread on a sheet pan to freeze individually, then transfer to bags. Frozen mulberries keep for a year or more and are excellent in baking, smoothies, and jam.
Harvest regularly during peak season — fruit left on the tree or on the ground attracts birds, spotted wing drosophila, and yellow jackets, all of which accelerate pressure on the remaining crop. During peak ripening, plan to harvest every 1–3 days.
Growing in containers
Standard mulberry varieties are generally too large and water-demanding to thrive long-term in containers. Gerardi Dwarf is the exception — its naturally compact size (6–8 feet) and heavy bearing make it the only Raintree mulberry recommended for container culture. Use a large container — minimum 25–30 gallons — with excellent drainage. Container-grown mulberries dry out quickly and may need daily irrigation during hot weather; this is the primary challenge of container culture for this thirsty species.
Use a quality potting mix with added compost — do not use straight garden soil, which compacts poorly in containers and limits root development. Refresh the top layer of potting mix annually and fertilize more frequently than in-ground trees, as nutrients leach out with regular watering. Regular pruning to maintain size is essential; without it, a Gerardi Dwarf will outgrow its container within a few seasons.
Common problems
Popcorn Disease
Moderate — fruit loss
Caused by the fungus Ciboria carunculoides. Developing fruit carpels are replaced by hardened fungal sclerotia that swell and extend beyond healthy berries, giving the infected fruit a popcorn-like appearance. Occurs in late spring to early summer during and after bloom. White mulberry varieties and hybrids (including Illinois Everbearing) are more susceptible; red and black mulberries are generally more resistant. Does not harm the tree — only ruins affected fruit. A significant concern for commercial growers; less critical for home growers where losing some fruit is acceptable.
- Sanitation is the primary control — collect and remove all infected fruit from the tree and the ground as it appears; do not compost infected material
- Bury removed fruit deeply or bag and dispose to prevent spore dispersal
- Applying Bordeaux mixture at bloom may provide some preventive protection
- Choose black or red mulberry varieties in areas where popcorn disease is a persistent problem
Cercospora Leaf Spot
Moderate — wet climates
Two cercospora fungi (C. moricola and C. mori) cause reddish-brown to purplish-haloed spots on mulberry leaves. Spreads via water splash and is most active during rainy weather or when foliage is regularly wetted. More common in humid climates. Black mulberry (M. nigra) is particularly susceptible in persistently wet conditions.
- Water from below — drip or soaker irrigation rather than overhead; water early enough in the day that foliage dries before nightfall
- Prune out and destroy infected branches; do not compost — burn or bag for disposal
- Apply preventive fungicide sprays beginning at bud break, repeated every 10–14 days during wet periods
- Keep the area beneath the tree clear of fallen leaves and debris where spores overwinter
- If severely infected repeatedly, consider replacing with a more resistant variety
Fusarium Canker
Moderate
Elongated lesions in the bark of branches or the main trunk. The canker disrupts the flow of nutrients and water, causing dieback of the branch above the infection. Cutting through the branch at the lesion site reveals dark discoloration in the wood — a diagnostic indicator. No effective chemical controls exist.
- Prune infected branches at least 3 inches below the visible infection; confirm clean wood (no dark discoloration) at the cut
- Destroy all pruned material by burning or bagging — do not compost
- Disinfect pruning tools between cuts with a 10% bleach solution or 70% isopropyl alcohol to prevent spreading the pathogen
Spotted Wing Drosophila (SWD)
Moderate — late-ripening varieties
Drosophila suzukii attacks ripening and ripe mulberry fruit, particularly later in the season when SWD populations are highest. Early-ripening varieties (Gerardi Dwarf, Kokuso) often complete harvest before SWD pressure peaks; late-ripening varieties (Pakistan, some Illinois Everbearing fruit) are more vulnerable. Larvae inside fruit cause rapid softening and decay.
Spotted wing drosophila — the adult; females lay eggs in sound, ripening fruit with a saw-like ovipositor. Photo: Martin Cooper (CC BY 2.0), via Wikimedia Commons — resized.
- Monitor with SWD traps from midsummer through harvest; apply spinosad-based insecticides (Monterey Garden Insect Spray; Entrust for organic) per label if adults are detected and fruit is ripening
- Harvest ripe fruit promptly — every 1–3 days at peak season; do not leave ripe fruit on the tree
- Remove all dropped fruit from beneath the tree regularly
- Choose early-ripening varieties to minimize overlap with peak SWD season
Birds
High — serious fruit loss
Birds — robins, starlings, cedar waxwings, and many others — consider ripe mulberries a premium food source and will harvest aggressively. A large, productive mulberry tree can lose a significant portion of its crop to birds within days of peak ripeness. This is perhaps the most practically significant pest problem for mulberry home growers.
- Netting a large mulberry tree is impractical — the most effective strategy is harvesting ahead of the birds by picking every 1–2 days as fruit ripens
- On compact varieties like Gerardi Dwarf, netting the whole canopy before fruit colors is feasible and highly effective
- Reflective bird scare tape provides short-term deterrence; birds habituate within a season
- Accepting bird losses on a large tree and harvesting the abundance that remains is a practical approach
Deer
High — young trees
Deer browse mulberry foliage readily, particularly on young trees where the entire canopy is accessible. Established trees with canopies above browse height are far less vulnerable, but young trees in the first 2–3 years after planting can be completely stripped.
- Protect young trees with an 8-foot woven wire fence or individual tree cage until the canopy grows above browse height
- Hardware cloth or plastic mesh tree guards protect the trunk from rubbing damage year-round
- Repellents provide inconsistent protection and require frequent reapplication
Voles and Mice
Moderate — young trees
Voles and mice chew bark from the base of young trunks at ground level, particularly in winter under snow cover or dense mulch. Girdling the trunk — removing bark all the way around — kills the tree. Rabbits cause similar damage up to 8–10 inches above ground.
- Keep mulch pulled back 4–6 inches from the trunk at all times — mulch against the trunk is prime vole habitat in winter
- Keep grass short within 1–2 feet of the trunk
- Wrap the lower trunk with a hardware cloth cylinder or commercial tree guard until the bark has thickened — typically 2–3 years after planting
Brown Marmorated Stink Bug (BMSB)
Low — monitor
BMSB is established in the PNW and feeds on mulberry fruit, causing poking-type damage followed by corky, decayed areas in the flesh. Brown spots can also develop in stored fruit. Less preferred than some other fruits but can be an issue where BMSB populations are high.
- Monitor with BMSB traps; see stopbmsb.org for current management recommendations
- Harvest ripe fruit promptly; remove and dispose of damaged or dropped fruit
- If found overwintering in the home in fall, vacuum rather than crushing — crushing releases a defensive odor
Seasonal care calendar
Winter
Dec - Feb
- Dormant pruning — best done in late January through February before bud break; minimize sap bleed by pruning while fully dormant
- Remove dead, crossing, or crowded branches; head back to desired height if managing tree size
- Check trunk guards on young trees; replenish if needed before vole season peaks under snow
- Pull mulch back from trunk base; inspect for rodent activity
Early Spring
Mar - Apr
- Apply 2–3 inches of compost over the root zone before new growth begins
- Restore mulch layer to 3–4 inches; keep pulled back from trunk
- Monitor for late frost — new mulberry growth is frost-tender; row cover or overhead irrigation can protect young foliage on frost nights
- Apply preventive fungicide at bud break if cercospora leaf spot was a problem the prior season
Late Spring
May - Jun
- Bloom and early fruit set — monitor for popcorn disease; begin removing infected fruit immediately as symptoms appear
- Begin supplemental irrigation if dry weather develops — consistent moisture is important for fruit sizing
- Install bird netting on compact varieties (Gerardi Dwarf) before fruit begins to color
Summer — Harvest
Jun – Aug
- Harvest ripe fruit every 1–3 days at peak season; spread tarp under canopy and shake for easy collection
- Monitor SWD traps from midsummer; apply spinosad if adults detected and fruit is ripening
- Remove dropped fruit from beneath the tree promptly — it attracts SWD, yellow jackets, and birds
- Maintain consistent deep irrigation through harvest, especially in dry-summer climates
- Refrigerate or freeze harvested fruit promptly — mulberries do not keep at room temperature
Fall
Sep - Nev
- Complete harvest; rake and remove all fallen fruit from beneath the tree — reduces disease and pest overwintering sites
- Continue irrigation until trees are fully dormant if fall is dry
- Collect and remove fallen leaves if cercospora leaf spot was present — spores overwinter in leaf litter
Late Fall
Nov – Dec
- Apply fresh 3–4 inch mulch layer over root zone; keep back from trunk
- Install or check trunk guards on young trees before snow arrives
- Order new trees or replacement stock early — popular varieties sell out quickly each season