Hican Tree Growing Guide
The short answer: A hican is a pecan-hickory hybrid (Carya illinoinensis crossed with another Carya species) whose suitability depends on the selection and site. Check local winter survival, nut maturity, and bearing records before planting. Plan compatible pollen nearby unless the selection is known to be self-fertile; expect several years before cropping, with substantial variation in bearing age and yield. Choose it for a long-term planting and locally demonstrated nut quality.
1. Introduction
Hican is a hybrid between pecan (Carya illinoinensis) and another hickory species. Shagbark (C. ovata), shellbark (C. laciniosa) and bitternut (C. cordiformis) crosses are documented. Use known parent species when describing a selection. Carya × dunbarii is shellbark × shagbark, without pecan parentage; the pecan × bitternut cross is C. × brownii. Hybrid parentage does not guarantee a thin shell, superior flavor or increased cold-hardiness.
In practice, hican is an enthusiast’s tree rather than a reliable commercial crop. Most named selections are variable bearers — some productive, many shy or erratic — and performance at any given site can differ significantly from origin reports. Trees become large and can take many years to bear. Grafting preserves a named cultivar; seedlings can also be grown, but they are genetically variable and generally take longer to produce. Plant one knowing it is a long-term investment with an honest chance of disappointing yields. Some selections have desirable flavor and cracking quality, while others fill poorly or disappoint. Overlapping parent ranges are a reason to investigate local records, not a guarantee of better nuts. Use local cultivar records to assess winter survival and nut ripening; a broad USDA zone range is only a preliminary screen.
Table of Contents
Quick Facts Table
Aspect | Details |
|---|---|
| USDA Hardiness Zones | Verify the named selection locally; parent species and a broad zone range do not establish reliable cropping |
| Mature Height | Often a large tree; mature height varies by selection and growing conditions |
| Mature Spread | Allow a broad canopy; use mature trees of the identified selection to estimate space |
| Time to First Harvest | Several years; cultivar and site matter, and seedlings generally bear later than grafted trees |
| Chill Hours Needed | Do not infer chilling from USDA hardiness zones; verify cultivar performance and local spring growth |
| Soil pH | Aim near 6.5 as a starting target; use soil testing and local nut-tree recommendations |
| Lifespan | Plan for a long-term tree; longevity varies with the selection, site and tree health |
| Pollination | Wind-pollinated; most selections need compatible pollen, with reported self-fertile exceptions such as Burton and Burlington |
Key Takeaway: Choose a locally proven selection, verify its pollination needs, and allow ample mature space. Bearing age and crop size vary; plan for a long-term tree without assuming a fixed yield schedule.
2. Choosing the Right Variety
Choose a hican using documented local performance, including kernel filling and bloom timing. Burton has favorable reports from Kentucky and Ontario, but performance still varies by site. A cultivar name or a large nut alone does not establish dependable yield.
Hican information includes Extension summaries, cultivar-register descriptions and orchard observations. These do not establish universal cultivar zone limits or a nationwide reliability ranking. The climate column therefore calls for local evidence of both winter survival and mature, filled nuts. Confirm source-tree identity, especially where similar historical names occur. Older parentage descriptions may be provisional; distinguish a register record from a genetically verified pedigree.
Variety Comparison Table
Cultivar | Parentage | Climate Evidence | Bearing Habit | Notes |
|---|---|---|---|---|
| McAlester | Pecan × shellbark hickory (C. laciniosa) | Verify locally | Confirm local bearing and kernel-filling records; no nationwide reliability ranking established | Verify source-tree identity and performance with the propagator; treat as a trial where local records are unavailable. |
| Burton | Pecan × shagbark hickory (C. ovata) | Verify locally | Favorable bearing reports from Kentucky and Ontario; trial locally before planting multiples | Originated near Owensboro, Kentucky; reported to ripen in Ontario. Local conditions still govern crop reliability. |
| Henke | Pecan × shagbark hickory (C. ovata) | Verify locally | Compare local bearing and nut-quality records before choosing; a blanket poor-performance ranking is not supported | Listed in university and arboretum collections; tree presence alone does not establish local crop reliability. |
| Pleas | Pecan × bitternut hickory (C. cordiformis) | Verify locally | Evaluate local bearing, kernel filling and flavor; records do not establish a nationwide production rating | USDA research records Pleas as a pecan–bitternut hybrid accession from Oklahoma. Confirm the identity of propagated stock. |
| Underwood (Jay Underwood) | The cultivar register records (Carya × brownii) × C. laciniosa, involving pecan, bitternut and shellbark | Verify locally | Verify bearing and pollen records for the specific clone; suitability cannot be reduced to a universal pollinizer-only role | The cultivar register places its origin at Fort Scott, Kansas, and describes protogynous flowering and light-to-medium production. Confirm the identity of propagated stock. |
| James | Described in the 1980 Ontario nut-grower newsletter as a pecan × shellbark selection | Verify locally | Historical report calls it promising but relatively untried; seek current crop records | The 1980 report places James in north-central Missouri; it does not establish a broad adaptation range. |
| Gerardi | Pecan × shellbark hickory (C. laciniosa) | Verify locally | Historical records differ on nut filling; Ontario reports caution against expecting dependable filled kernels in the North | The cultivar register records an Illinois origin and early, protogynous flowering. Judge yield and filling from identified trees at comparable sites. |
Pollination Type
Plan hican pollination by cultivar and actual flowering overlap. Kentucky Extension identifies Burton and Burlington as self-fertile exceptions to the usual need for compatible pollen. For other selections, confirm a suitable pollen source before planting. The pecan pollination guide explains flowering timing, but a pecan type label alone does not establish compatibility with a particular hican.
3. Site Selection & Preparation
Choose full sun, deep well-drained soil, reliable moisture, and ample mature space. Test soil before planting; a pH near 6.5 is a useful starting target under Kentucky nut-tree guidance, with amendments based on the test and local advice.
Full sun, adequate moisture, and deep, well-drained soil support nut-tree growth and production. Assess rooting depth and drainage as well as surface fertility. Use soil-test recommendations to decide whether amendments are needed; high pH can affect nutrient availability, but a pH reading alone does not diagnose a particular deficiency.
Drainage and Taproot Care
Choose well-drained ground and healthy nursery stock with roots protected from drying and damage. Both bare-root and container-grown trees need careful handling. Keep the prepared roots in their natural position at planting, and provide water and weed control during establishment. Root condition, planting depth, drainage, and aftercare all matter.
Spacing Guidelines
Planting Type | Spacing Considerations |
|---|---|
| Nut-tree or silvopasture planting | Base spacing on mature canopy size, light for nut production or forage, equipment access and planned thinning; 50 feet is not a universal minimum |
| From buildings and permanent structures | Allow for the mature canopy, roots, utilities, and maintenance access; use site-specific clearance rather than a fixed setback |
| From pollinizer tree (pecan or hickory) | Keep compatible pollen sources nearby while allowing mature canopy space; distance alone does not establish successful pollination |
4. Planting Instructions
Plant dormant stock into workable soil before growth starts. Set the root collar at finished grade, keep the graft above soil, and size the hole to the prepared roots. Water thoroughly and monitor root-zone moisture during establishment.
When to Plant
- Container-grown grafted stock: Plant during dormancy where practical, into workable soil. Inspect the root system and protect the root ball during handling; local soil and weather conditions determine the planting window.
- Bare-root stock: Plant while dormant before growth begins. Keep roots moist and protected until planting; follow the nursery’s handling instructions and trim broken roots cleanly.
Planting Depth and Graft Union
Dig wide enough for lateral roots to spread naturally and deep enough for the prepared root system without bending the taproot or burying the trunk. Set the root collar at finished grade and keep the graft union above soil. Support the roots firmly enough to prevent settling, backfill with native soil, and water thoroughly.
Watering and Establishment
Water thoroughly at planting to settle soil around the roots. Mulch a broad area while keeping the trunk and root collar clear. Check root-zone moisture regularly and water when needed through establishment, adjusting for rainfall, heat, soil drainage, and tree size.
5. Pollination and Nut Set
Most hicans need a compatible pollen source, but Burton and Burlington are reported as self-fertile. Match pollen shed to receptive female flowers and allow room for the mature trees.
Hicans are wind-pollinated. Many selections need cross-pollination, but flowering behavior varies: Kentucky Extension reports Burton and Burlington as self-fertile. For a selection needing a partner, verify that the partner sheds viable pollen while its female flowers are receptive. Type I and Type II labels describe timing patterns; they do not by themselves prove overlap or compatibility.
Pollinizer Options
- Another hican cultivar: Choose a documented compatible partner whose pollen shed overlaps receptive flowers; confirm local bloom timing with the propagator or an experienced grower.
- Compatible pecan cultivar: Kentucky guidance identifies early pollen-shedding pecans such as Major as possible partners for hicans needing cross-pollination. Verify overlap with your selection; proximity alone is not enough.
- Wild hickory nearby: May contribute pollen in some years, but bloom timing cannot be relied on as a sole strategy.
6. Pruning and Training
Train a strong central leader and well-spaced scaffold branches while the tree is young. Choose lower clearance for the intended use, and make small corrective cuts early. Established trees generally need limited maintenance pruning.
Early training should develop a strong framework while retaining useful foliage. Inspect the tree during dormancy and use selective shoot training during growth when needed. Mature nut trees generally need less structural intervention once that framework is established.
Training the Young Tree
Maintain one dominant central leader and address competing leaders while they are small. Select strong, well-spaced scaffold branches around the trunk. A lowest scaffold around 5–6 feet can provide equipment clearance; adjust this to the site and raise the canopy gradually rather than stripping all lower growth at once.
Maintenance Pruning
Inspect regularly for dead, broken, rubbing, or poorly attached branches. Make needed cuts while branches are small and preserve the branch collar when removing a branch. Routine structural pruning is commonly done during dormancy, with selective training during growth. Suspected cankers need diagnosis and disease-specific pruning advice; use a qualified arborist for large or hazardous limbs.
7. Ongoing Care & Maintenance
Provide adequate moisture as nuts develop, monitor tree health, and use soil testing and local guidance to plan nutrition. Fertilizer needs and watering frequency depend on the tree and site.
Care needs depend on the selection, site, crop, and pest pressure. Monitor moisture and tree health, base nutrition on testing, and use sanitation as one part of pest management.
Watering
Stage | Guidance |
|---|---|
| Establishment | Check root-zone moisture regularly. Water thoroughly when needed; drip run time depends on emitter flow, soil, and the area being wetted. |
| Young, actively growing tree | Continue monitoring during dry weather. Adjust irrigation to rooting depth, soil moisture, weather, and tree growth. |
| Established tree | Established trees still need adequate water for nut development. Monitor moisture throughout dry periods and nut filling rather than relying on a single seasonal watering. |
| Nut fill (timing varies) | A critical period for water supply. Follow local crop development and root-zone moisture; water stress can reduce kernel filling. |
Fertilization
- Young trees: Avoid fertilizer in the planting hole. Base later applications on soil-test recommendations, growth, and local nut-tree guidance; tree age alone does not determine a suitable rate.
- Established trees: Follow local guidance for soil and leaf testing. Diagnose suspected zinc deficiency before treatment; an effective application program depends on the diagnosis, product, and growing conditions.
- Fertilizer timing: Follow local recommendations and avoid stimulating late growth that may not harden before cold weather.
Inspect wood-chip mulch and replenish as it decomposes, keeping it clear of the trunk and root collar. Avoid adding a new layer automatically when sufficient mulch remains.
8. Pest and Disease Management (Organic)
Monitor hicans for locally important nut-tree pests and diseases, including pecan weevil and shuckworm. Identify the cause of damage before treatment. Sanitation and cultivar selection help, but pest pressure and the difficulty of treating a large canopy can limit home production.
Hicans can share pests with related nut trees, but susceptibility varies. Spraying a large canopy is difficult for most home growers. Combine cultivar selection, sanitation, monitoring, and diagnosis; some infestations remain difficult to manage with home equipment or organic options.
Diseases
Disease | Identification & Management |
|---|---|
| Pecan Scab (Venturia effusa) | Dark lesions can develop on susceptible growth and shucks, with greater pressure in wet conditions. Manage: use locally documented resistance, airflow, sanitation, and disease monitoring. Organic fungicides provide limited suppression; any treatment needs a crop-specific label and locally appropriate preventive timing during susceptible growth. |
| Canker (various fungi) | Sunken or discolored bark and branch dieback can indicate a canker. Manage: obtain a diagnosis, reduce tree stress, and remove affected branches back to healthy wood where appropriate. Preserve the branch collar; a fixed six-inch margin does not suit every canker or branch. Trunk cankers and large damaged limbs need professional assessment. |
| Wood Decay (bracket fungi) | Fungal brackets on trunks or major branches indicate wood decay, whose extent may be hidden. Have a qualified arborist assess the tree, especially near people or structures. Risk depends on the location and extent of decay and the remaining sound structure; tree size alone does not determine it. |
Pests
Pest | Identification & Management |
|---|---|
| Pecan Weevil (Curculio caryae) | Adults lay eggs in developing nuts; larvae consume kernels and later enter the soil. Emergence timing varies with location and soil moisture. Manage: install Circle traps before expected emergence to intercept adults climbing the trunk, and check them regularly. Some adults fly into the canopy, so trapping is also a monitoring tool. Remove infested nuts promptly and follow local guidance for further control. |
| Hickory Shuckworm (Cydia caryana) | Larvae damage developing nuts and shucks; damaged shucks may stick to nuts. Several generations can occur in a season. Manage: remove infested shucks and nuts, monitor crop development and pest activity, and obtain local treatment guidance. If a spray is warranted, use a product labeled for the crop and pest before larvae become protected inside plant tissue. Organic eligibility depends on the specific formulation; check the product rather than assuming all spinosad formulations qualify. |
| Black Pecan Aphid (Melanocallis caryaefoliae) | Feeding causes angular yellow patches that can turn brown and lead to early leaf loss, reducing nut quality and later flowering. Manage: confirm the insect, inspect leaf undersides and protect beneficial insects. Follow local monitoring thresholds; if treatment is needed, choose a product labeled for the crop and pest, with suitable canopy coverage and verified organic eligibility. Old leaf spots alone do not show that aphids are still present. |
| Squirrels | Can remove immature and mature nuts. Manage: gather mature nuts promptly as they release. Smooth trunk baffles can help on isolated trees, but squirrels can bypass them through nearby branches or structures. Allow for trunk growth and inspect attachments; a connected canopy limits exclusion. |
Juglone note: Published walnut sensitivity lists rely largely on observations, with disagreements and many untested plants. They do not establish a strict hican exclusion list or guarantee tolerance. Assess shade, root competition, soil moisture, drainage, and other causes of plant stress as well.
9. Harvest and Storage
Harvest as mature nuts release and fall, with timing varying by selection and location. Remove shucks, dry the nuts with good airflow, and check sample kernels before storage. Cool storage and suitable packaging help preserve quality.
Harvest timing depends on the selection and location. Gather mature nuts promptly as they release and fall, limiting animal losses and prolonged contact with damp ground.
Hulling and Curing
Remove remaining shucks and spread nuts in shallow layers with good airflow, protected from animals. Check sample kernels as drying progresses; hican is handled much like hickory. Drying time depends on initial moisture and air conditions. Kernels should become crisp before storage; do not seal damp nuts in an airtight container.
Cracking
Shell thickness and cracking quality vary among selections. Choose a cracker suited to the nuts and adjust pressure to avoid crushing kernels. Separate shell fragments carefully before eating or cooking.
Storage
Method | Approach & Shelf Life |
|---|---|
| In-shell, cool and dry (40–50°F) | Store properly dried nuts in a clean, dry, well-ventilated place protected from animals. Refrigerate or freeze for longer keeping. |
| In-shell, refrigerated (34–38°F) | Keep dried nuts protected from moisture and odors. Storage life depends on initial quality, dryness, temperature, and packaging. |
| In-shell, frozen | Freeze properly dried nuts in moisture-resistant packaging. Keep them packaged while warming to limit condensation on the nuts. |
| Shelled kernels, refrigerated | Use airtight packaging and keep cold. Use small pieces sooner than whole kernels, or freeze for longer storage. |
| Shelled kernels, frozen | Freeze dried kernels in airtight, moisture-resistant packaging. Long storage can reduce flavor and texture; label containers with the harvest date. |
| In cooking | Use good-quality kernels in recipes that call for pecans or hickory nuts. Taste a sound sample first: flavor and bitterness vary among selections, and hybrid parentage does not guarantee a rich, mild kernel. |
Yield Expectations
Be honest with yourself about the timeline and variability before planting:
- Early years: Bearing age varies by selection and site. Confirm its pollination needs before planting; self-fertility and time to first crop are separate traits.
- First crops: Timing and crop size vary widely. Use records from the cultivar and comparable sites rather than assuming a particular age produces a set number of pounds.
- Mature trees: Some selections crop well while others remain shy or irregular. Track annual in-shell yield and kernel filling to judge performance at your site.
- Choosing for production: Compare documented local yields and nut quality before committing space. A locally proven pecan may be a better fit when consistent nut production is the priority.
10. Companion Planting (The “Hican Grove”)
Plan companion plants around the mature canopy, available moisture, and harvest access. Keep competing vegetation away from newly planted hicans, and give fruiting companions enough light for the crop you want.
A large hican can create substantial shade and root competition. Match companions to the light and soil moisture actually available as its canopy grows. Compass direction and the dripline alone do not define a suitable planting spot; reserve adequately sunny space for crops grown primarily for fruit or nuts.
Companion | Role in the Guild |
|---|---|
| Locally adapted grasses | Managed ground cover where light and moisture suit the chosen species; control competition close to young trees. |
| White or Crimson Clover | Possible managed orchard cover. Nitrogen becomes available as plant material decomposes, but clover can still compete with tree roots for water and nutrients. |
| Pawpaw (Asimina triloba) | Tolerates shade, but best fruit production generally needs more light. Give it adequate moisture and growing space rather than assuming a dense nut-tree canopy is an ideal fruiting site. |
| American Persimmon (Diospyros virginiana) | Grows in sun to partial shade; give a fruiting tree ample light and space. Ripening varies by cultivar and location, so do not assume every American persimmon provides a late-fall crop. |
| Comfrey | Optional biomass plant for cut mulch where space allows; do not assume it corrects hican nutrient deficiencies. It can persist and spread from root fragments. |
| Native Asters, Goldenrod | Flowers for insects; select species suited to the available light and moisture. Hican pollination itself is wind-driven during flowering, not during nut fill. |
| American Hazel (Corylus americana) | An option in sun to light shade with adequate space; partial-shade survival does not guarantee a productive crop beneath a dense canopy. |
Give sun-loving crops their own adequately lit space as the hican canopy expands. The walnut guide discusses the limits of juglone lists; use those lists as cautious observations rather than proof of compatibility or a universal safe distance.
11. Regional Growth Profiles
Regional guidance is a starting point. Confirm that the named selection survives local winters and fills nuts before damaging fall cold. Native parent ranges and winter-hardiness zones alone do not establish dependable yields.
Compare reports from similar sites and identified cultivars. Kentucky guidance and northern grower observations are useful starting points, but neither establishes uniform performance across an entire region.
Region | Outlook & Notes |
|---|---|
| Pacific Northwest | Cool maritime summers may constrain nut maturity. Seek local records of filled nuts from the named selection before planting for a dependable crop. |
| California | Seek records for the named selection at a comparable California site. A Zone 8 or 9 rating and pecan parentage do not establish reliable hican cropping; evaluate winter growth, summer conditions, water supply and nut maturity separately. |
| Desert Southwest | Treat as a local trial unless there are documented results for the selection and site; assess heat, winter conditions, soil, and irrigation. Pecan is grown commercially in southern New Mexico; hican is largely untested. |
| Intermountain West | Evaluate season length, winter cold, soil, and water separately. Local evidence of ripe, filled nuts is needed before promising a harvest. |
| Great Plains | Performance must be checked by cultivar and location; native pecan or hickory nearby does not establish that a hybrid will crop reliably. McAlester needs its own locally verified performance record; a regional label or parent species alone does not establish adaptation. |
| Ozarks & Interior Highlands | A reasonable region to seek local cultivar records, but overlapping parent ranges do not establish a nationwide best region or guarantee nut filling. |
| Upper South / Mid-South | Kentucky Extension describes useful selections, including Burton and Burlington. Apply those reports cautiously to other sites and confirm local bearing, nut maturity, and pollination. |
| Southeast & Gulf Coast | Check local disease pressure, winter growth patterns, and cultivar records. Shellbark parentage alone does not establish suitability for warm Gulf Coast sites. |
| Mid-Atlantic | Seek evidence of winter survival and mature crops from the named selection. A native hickory population or Zone 6–7 rating alone does not establish reliable hican yields. |
| Northeast & New England | Seek documented winter survival and filled, mature nuts from comparable New England sites. A protected site, Zone 6 designation or shagbark parentage alone does not establish suitability; treat an unproven selection as a trial. |
| Great Lakes & Upper Midwest | Use documented local selections and distinguish winter survival from nut maturity. At the coldest sites, treat hican as experimental unless mature-crop records support the planting. |
Frequently Asked Questions
What is a hican?
A hican is a hybrid between pecan (Carya illinoinensis) and another hickory species, including shagbark, shellbark or bitternut. Nut size, shell thickness, flavor, cold-hardiness and bearing vary by selection. Evaluate identified stock using local crop records; the hybrid name does not promise a particular combination of desirable traits.
Do hicans need a pollinizer?
Most selections need compatible pollen, but Kentucky Extension reports Burton and Burlington as self-fertile. Choose a partner using documented compatibility and actual overlap between pollen shed and receptive flowers. Keep pollen sources nearby while allowing mature canopy space.
What hardiness zones can grow hicans?
Check the named selection against local winter survival and nut-ripening records. USDA zones describe winter extremes, not summer warmth, season length, or chilling. Shagbark versus shellbark parentage alone does not determine a reliable cropping range.
How long until a hican bears nuts?
Expect several establishment years, but bearing age varies with the cultivar, tree, and site. Grafted trees generally produce earlier than seedlings. Check local records for the selection; age alone does not predict a fixed number of pounds, and some trees remain irregular bearers.
12. Resources & Further Reading
Use cultivar records and identified orchard observations to evaluate hicans. Historical reports describe particular trees and sites; they are not nationwide trials. Pecan and hickory publications provide related care guidance, whose applicability should be checked for the selection and local conditions.
Cultivars, parentage and pollination
- USDA Forest Service: Shellbark Hickory Hybrid Parentage
- USDA ARS: Carya Species and Hybrid Classification
- Kentucky Extension: Hican Cultivars and Burton Origin
- NNGA 1951 Proceedings: Burton Hican Provenance
- Society of Ontario Nut Growers: Burton Performance Observations
- Kentucky Woodlands Magazine: Hican Self-Fertility and Pollen Sources
- New Mexico State University: Pecan Flowering Overlap
- USDA: What Hardiness Zones Measure
- NDSU-Hosted 2022 Nut-Growing Presentation: Limits of Northern Hican Evidence
- University of Nebraska: Henke Hican Parentage
- Iowa Arboretum: Henke Hican Collection Record
- Illinois Extension Historical Circular: Regional Hican Selections
- USDA-led Carya research: Pleas accession and hybrid classification
- Ontario Nut Growers, 1980: Historical observations of hican selections
- Cultivar register: Jay Underwood parentage, origin and flowering
- Cultivar register: Gerardi origin and flowering
- Cultivar register: Burton characteristics
- Cultivar register: Henke characteristics
Planting and tree care
- Oklahoma State Extension: Nut-Tree Establishment and Site Preparation
- Georgia Extension: Root Placement and Planting Depth
- Oklahoma State Extension: Nut-Tree Water and Nutrition
- Oklahoma State Extension: Central-Leader Training and Branch Collars
- New Mexico State University: Young Nut-Tree Training
- Minnesota Extension: Pruning and Tree Structure
- Missouri Extension: Mature space and fruiting-tree site requirements
- Wisconsin Extension: Silvopasture spacing, equipment access and canopy management
Pests and diseases
- Georgia Extension: Limits of Organic Disease and Pest Management
- Texas A&M AgriLife: Weevil and Shuckworm Biology
- Mississippi State Extension: Organic Eligibility Depends on Formulation
- Maryland Extension: Canker Symptoms and Management
- Oklahoma State: Black pecan aphid damage and hosts
- Georgia Extension: Aphid identification, monitoring and beneficial insects
- Missouri Extension: Squirrel exclusion and connected canopies
- Missouri Conservation: Baffles on isolated trees and allowance for growth
- UC IPM: Wood decay and tree assessment
- Penn State: Decay does not alone determine tree failure risk
Harvest and companion planting
- Wisconsin Extension: Limits of Juglone Plant Lists
- Purdue Extension: Observational Walnut Sensitivity Guidance
- Oklahoma State Extension: Clover Nitrogen and Root Competition
- Utah State Extension: Comfrey Growth and Persistence
- Kentucky State University: Pawpaw Light and Fruiting
- Cornell Extension: Pawpaw Site Requirements
- Oregon State University: American Hazel Light Requirements
- NC State Extension: American Hazel Culture
- New Mexico State University: Nut Moisture, Packaging, and Storage Quality
- Georgia Extension: Drying Conditions and Storage Quality
- NC State: American persimmon light and fruiting season