Dahlia Doctor Research Library: Lifting and Curing Dahlia Tubers

A Curated Knowledge Card Collection

Copyright © 2026 by Steve K. Lloyd
All Rights Reserved

Every autumn, dahlia growers face the same practical question: when is the right time to dig? The answer is not simply “after the first frost.” Storage-organ readiness is a physiological state, not a calendar date. A tuber lifted too early, or handled carelessly after lifting, enters storage without the protective skin, sealed wounds, and stable biochemistry it needs to survive the winter.

This collection assembles the research evidence behind those processes: what determines when a storage organ is ready, how barrier tissue forms after injury, and how drying and temperature management in the hours and days after lifting shape what survives to spring.

The collection draws on both dahlia-direct evidence and adjacent research from potato, sweet potato, and Zantedeschia. Potato and sweet potato periderm biology and curing physiology are the most thoroughly studied analogs available for fleshy storage organs. The principles governing suberization, wound periderm formation, and carbohydrate stability during curing are grounded in extensive experimental literature. Zantedeschia, or Calla lily, provides cautiously applicable geophyte evidence on drying conditions, storage temperature, desiccation, and storage losses. Where the evidence base is non-dahlia, the practical implications are treated as informative analogy rather than direct prescription.

Each post in this series presents a curated set of Dahlia Doctor Knowledge Cards organized around a specific research topic. A Knowledge Card summarizes one scientific or technical source using a consistent structure: study system, experimental context, experimental design, key results, mechanistic insight, practical guidance, and why the source matters to dahlia growers and researchers.

These summaries represent original interpretive work. They are intended as a research guide, not a substitute for reading the original papers. Each citation title links to a Google Scholar search for that source, opening in a new tab, to help you locate the original publication independently.

Each Knowledge Card appears once in this collection, placed in the topic cluster where it contributes most directly. Some sources are relevant to more than one cluster. Placement reflects primary emphasis rather than exclusive relevance.

KC-0014, Ivanova and Zaprjanova (2020), appears here in the context of field maturity and phenological readiness. Its comparison of in-ground versus lifted-and-replanted tubers provides dahlia-direct evidence on overwintering timing. This source is also relevant to the companion collection on dahlia tuber storage, dormancy, and overwinter survival, where its data on emergence timing and flowering duration have additional application.

KC-0418, Van Leeuwen and Trompert (2005), appears here for its tuber maturity, drying regime, and potting-up moisture findings. The Erwinia chrysanthemi findings and poppers disease narrative from this same source are treated more fully in the companion collection on dahlia tuber rot, poppers, and clean stock.

This collection includes non-dahlia sources from potato, sweet potato, and Zantedeschia research. These are used as the best available analogs for storage-organ barrier formation, curing physiology, drying conditions, and early storage viability. They are identified by study system in each Knowledge Card.

Publication Type
Experimental Research Article

Full Citation
Ivanova, V., & Zaprjanova, N. (2020). Study on phenological behaviours of Dahlia variabilis Hort. in overwintering of tuberous roots in the soil. Scientific Papers. Series B, Horticulture, 64(1), 588–591.

Study System
Dahlia variabilis Hort.; cultivars ‘Vitus’, ‘White Ball’, and ‘Dark Red’; tuberous roots overwintered in soil compared with tuberous roots lifted, stored, and replanted.

Experimental Context
Field study in an ornamental planting context under conditions where standard local practice involved spring planting of tuberous roots, autumn lifting, and winter storage in a dark ventilated place above 0°C.

Experimental Design
Tuberous roots of similar length and diameter were selected, each with part of the old stem. Plants were established in the second half of April. Control plants were lifted in the second half of October, cleaned, stored through winter, and replanted the following April. Experimental plants had stems cut to 10 cm in October and tuberous roots left in the soil for the next growing season. Vegetative and ornamental phenological traits were measured during the second vegetation period.

Key Results
Overwintered plants began sprouting earlier than lifted-and-replanted plants. Emergence occurred 15 to 27 days earlier by cultivar, and mass emergence occurred 21 to 43 days earlier. Overwintered plants reached maximum growth earlier, generally at the beginning of June, while lifted-and-replanted plants reached maximum growth later. Beginning of flowering occurred earlier in overwintered plants by 5.2 to 13.1 days after emergence, and mass flowering occurred earlier by 8.17 to 14.4 days. Individual flowers lasted 1.7 to 5.4 days longer on overwintered plants. Whole-plant flowering duration was longer in overwintered plants by 37.9% to 45%.

Mechanistic Insight
The study states that budding duration was not affected by cultivation mode, probably because dahlia belongs to the short-day plant group. The study identifies cultivar and overwintering treatment as factors associated with differences in emergence, growth rate, and flowering duration.

Practical Guidance
Under the tested conditions, leaving tuberous roots in the soil over winter produced earlier emergence, faster early growth, earlier flowering, and longer flowering duration than lifting, storing, and replanting. The study notes that future work should monitor soil temperature.

Why This Source Matters
This is direct dahlia field evidence on the phenological consequences of in-ground versus lifted overwintering. For growers weighing the costs and benefits of autumn lifting, these data provide a measured baseline: what is gained in earliness and flowering duration when tubers are left in soil, and what is traded away when they are lifted, stored, and returned to the ground in spring.

Publication Type
Technical Report

Full Citation
Van Leeuwen, P. J., & Trompert, J. P. T. (2005). Onderzoek naar oorzaak van ploffers in Dahlia: De invloed van knolrijpheid, minerale samenstelling, en teelt-, bewaar- en oplegomstandigheden op het optreden van ploffers [Investigation of the causes of “poppers” in dahlia: Effects of tuber maturity, mineral composition, and cultivation, storage, and potting conditions] (Report No. 330793). Praktijkonderzoek Plant & Omgeving.

Study System
Dahlia cuttings and tubers from production lots with high losses from ploffers during cutting production; cultivars included ‘Rosella’, ‘Sandra’, ‘Myama Fubuki’, and ‘Stolze von Berlin’.

Experimental Context
Multi-year investigation of wet-rot tuber collapse during cutting production after tubers were laid in greenhouse substrate and greenhouse temperature was raised to approximately 20 to 22°C.

Experimental Design
Three groups of trials tested tuber maturity and drying regime, tuber mineral composition, and cultivation, storage, and potting-up conditions. Tuber maturity trials varied planting date, harvest date, postharvest drying, and, in one trial, water conditions during cutting production. Mineral composition trials varied potassium, phosphate, trace-element foliar treatments, and production location. Cultivation, storage, and potting-up trials exchanged tubers among production, storage, and greenhouse-forcing locations. Additional observations followed a high-ploffer lot handled as potentially infected with Erwinia chrysanthemi.

Key Results
Tuber maturity trials produced large differences in tuber weight but generally few ploffers. One trial showed treatment differences that were not consistent or explained. Mineral composition trials produced large differences in tuber mineral content, but ploffer percentages did not show reproducible treatment effects. One trial showed only a tendency for trace-element sprays to reduce ploffers. Wetter and more humid potting-up conditions promoted ploffers. Cultivation and storage conditions sometimes affected ploffer percentages, but effects differed among years. In lots with high ploffer percentages, field losses and wilting symptoms were often observed. In one lot with almost 40% ploffers, treating the lot as potentially affected by Erwinia chrysanthemi coincided with reduction of ploffers to 6.5% in one year. Erwinia chrysanthemi was detected in part of the ploffers and in part of the tubers from plants showing wilting symptoms.

Mechanistic Insight
The report concludes that tuber maturity, mineral composition, cultivation conditions, and storage conditions sometimes influenced ploffer percentages but did not appear to be the cause. Wetter and more humid potting-up conditions increased ploffers. The final conclusion states that ploffers are very probably caused by Erwinia chrysanthemi, while noting that further testing was needed to determine whether this bacterium is the causal agent.

Practical Guidance
In one high-ploffer lot, treating the lot as potentially affected by Erwinia chrysanthemi coincided with reduction of ploffers to 6.5%. The observed handling included taking later cuttings, removing wilting plants during field production, and avoiding wetter or more humid potting-up conditions during cutting production.

Why This Source Matters
This report provides direct dahlia evidence on how tuber maturity, drying regime, and postharvest moisture conditions interact with storage and cutting-production outcomes. For growers and producers, the consistent finding that wetter potting-up conditions increased collapse rates reinforces the practical principle that controlled drying and moisture management after lifting are not optional refinements. They are protection against loss. The disease findings are treated more fully in the companion collection on dahlia tuber rot, poppers, and clean stock.

Publication Type
Review Article

Full Citation
Kumar, P., & Ginzberg, I. (2022). Potato periderm development and tuber skin quality. Plants, 11(16), 2099.

Study System
Potato tubers (Solanum tuberosum L.) periderm; native and wound periderm development, maturation, and skin quality disorders.

Experimental Context
Narrative synthesis of anatomical, transcriptomic, biochemical, hormonal, and postharvest studies on periderm development and skin quality.

Experimental Design
Literature review synthesizing research on periderm initiation, development, maturation, and the conditions that affect skin quality and wound periderm formation.

Key Results
Periderm development proceeds through initiation, immature growth, and maturation with skin set. Wound periderm follows a defined temporal sequence. Skin quality disorders arise from disruptions in phellogen regulation, suberin biosynthesis, hormonal signaling, or epigenetic control.

Mechanistic Insight
Coordinated phellogen regulation, suberin biosynthesis, hormonal signaling, and epigenetic control determine barrier function and skin quality. The review provides a comprehensive mechanistic framework for how tuber skin forms, matures, and responds to injury.

Practical Guidance
Optimizing curing and storage environments promotes rapid wound healing and durable skin set. Conditions that disrupt suberin biosynthesis or phellogen activity impair the protective function of the periderm and increase susceptibility to water loss and decay.

Why This Source Matters
This review establishes the biological framework that underlies all practical curing guidance. Understanding that skin set is not a passive drying process, and that it involves coordinated hormonal signaling, gene expression, and the orderly deposition of suberin, clarifies why curing conditions matter and why shortcuts have costs. For dahlia growers, this is the mechanistic foundation behind the recommendation to cure tubers under controlled warmth and humidity before moving them to cold storage.

Publication Type
Research Bulletin

Full Citation
Werner, H. O. (1938). Wound healing in potatoes (Triumph variety) as influenced by type of injury, nature of initial exposure, and storage conditions. Research Bulletin 102. Nebraska Agricultural Experiment Station.

Study System
Potato tubers (Solanum tuberosum L.), Triumph variety; mechanical injury at harvest followed by field exposure and storage under varying environmental conditions.

Experimental Context
Controlled injury types and timed exposure to sun and air, followed by storage in warm humid, humid cellar, dry cellar, or cold conditions.

Experimental Design
Histological sampling over time after injury and storage under defined environmental regimes; anatomical progression of wound healing documented.

Key Results
Wound healing proceeds through false cicatrice formation, suberization, phellogen initiation, and phellem development. Warm humid storage accelerates healing, while cold storage delays or prevents periderm formation.

Mechanistic Insight
Wound periderm formation depends on oxygen availability, temperature, humidity, and tissue context, progressing through ordered anatomical phases. Cold temperatures suppress the cellular activity required for each successive stage.

Practical Guidance
Prompt curing in warm, humid conditions reduces storage loss and disease risk. Immediate cold storage after injury increases losses because the protective periderm does not form before decay and desiccation can act on exposed tissue.

Why This Source Matters
This is one of the foundational studies documenting the sequential anatomy of wound healing in a starchy storage organ. For dahlia growers, the core message is unambiguous: a freshly dug tuber with a damaged surface does not have the protection it needs until wound periderm has formed. Cold storage applied immediately after lifting short-circuits that process. A warm, humid curing period is not a luxury; it is the condition under which the barrier tissue actually forms.

Publication Type
Doctoral Dissertation

Full Citation
Sinka, J. L. (2025). Metabolic and ultrastructural analysis of suberization in a wound-healing potato tuber (Doctoral dissertation, The University of Western Ontario).

Study System
Potato tubers (Solanum tuberosum L.); wound-induced periderm formation during postharvest injury.

Experimental Context
Laboratory investigation of the metabolic and structural sequence of suberization following mechanical wounding.

Experimental Design
Stable isotope labeling, metabolomics, RNAi knockdowns, transmission electron microscopy, and permeability assays applied to wound-healing tuber tissue sampled across a defined post-injury time course.

Key Results
Early carbon flux after wounding favors phenolic metabolism. Later aliphatic suberin deposition follows the establishment of the phenolic scaffold. Early disruption of the phenolic phase produces periderm that is structurally present but functionally compromised.

Mechanistic Insight
Effective suberin assembly requires two temporally distinct phases: an early phenolic scaffold that anchors the later aliphatic lamellae. Disrupting the sequence, whether by temperature, oxygen availability, or metabolic interference, produces barrier tissue that looks formed but does not perform its protective function.

Practical Guidance
Effective curing must support the correct temporal sequence of suberin biosynthesis. Conditions that interfere with early phenolic metabolism will compromise the final barrier even if the tuber later proceeds through later curing phases.

Why This Source Matters
This dissertation provides the most mechanistically detailed available account of what happens during suberization in a wounded storage organ. The finding that a structurally present barrier can be functionally compromised if the early phenolic phase is disrupted has direct implications for how curing conditions are managed. For dahlia growers, it reframes the curing question: the goal is not just to form some protective tissue, but to ensure that the tissue formed is actually functional.

Publication Type
Technical Report / Book Chapter

Full Citation
Van Oirschot, Q. E. A., Rees, D., Aked, J., Kihurani, A., Lucas, C., Maina, D., & Bohac, J. (2003). Curing and the physiology of wound healing. In Sweet potato postharvest assessment: Experiences from East Africa. Natural Resources Institute, Chatham, UK.

Study System
Sweet potato (Ipomoea batatas) storage roots; postharvest curing to promote wound healing and reduce decay.

Experimental Context
Synthesis of curing experiments varying temperature and humidity in postharvest handling contexts.

Experimental Design
Review and synthesis of experimental work on curing conditions and wound healing outcomes, including temperature and humidity variation trials.

Key Results
Curing accelerates periderm formation, reduces water loss, and lowers decay risk. The combination of warm temperature and high humidity is the operative condition for effective curing.

Mechanistic Insight
Wound-induced suberization and lignification form a protective barrier in response to mechanical injury. Temperature and humidity during the postharvest curing window determine the speed and completeness of that barrier formation.

Practical Guidance
Applying warm, humid curing conditions immediately after harvest reduces postharvest losses. Delay in establishing curing conditions allows water loss and decay to act on unprotected wound surfaces.

Why This Source Matters
Sweet potato offers adjacent evidence for interpreting dahlia curing. Mechanical injury in fleshy storage organs triggers suberization and lignification, and those processes are temperature- and humidity-dependent. This source synthesizes practical curing evidence for a storage root that is physiologically relevant to the questions dahlia growers face after lifting, while still requiring careful crop-specific interpretation.

Publication Type
Experimental Research Article

Full Citation
Heinze, P. H., & Appleman, C. O. (1943). A biochemical study of curing processes in sweet potatoes. Plant Physiology, 18(4), 548–564.

Study System
Maryland Golden Sweet Potato storage roots; curing under different combinations of temperature and relative humidity, then stored under favorable storage conditions.

Experimental Context
Storage roots cured under experimental temperature and humidity conditions and then held in long-term storage.

Experimental Design
Experimental lots were harvested and placed under defined curing conditions, cured for 10 to 11 days, then stored for four months at 50 to 53°F and 50 to 60% relative humidity. Moisture, pectic substances, and nitrogenous constituents were sampled at six representative roots per lot. Proximal and distal halves were compared for nitrogen distribution.

Key Results
Soluble pectin increased during curing in all lots except the lot cured at 86°F and low humidity; protopectin showed a corresponding decrease. During storage, protopectin increased again while soluble pectin decreased. Non-protein nitrogen increased and protein nitrogen decreased under all curing conditions, indicating protein hydrolysis. The rate of hydrolysis was somewhat higher at higher curing temperatures. Curing at 86°F with high relative humidity gave the best storage results for this variety. Higher curing temperatures were unsuitable because of internal breakdown during curing.

Mechanistic Insight
Curing involved pectic transformations and protein hydrolysis in storage root tissue. The study concluded that curing appears to involve multiple interrelated internal processes and that no single outstanding biochemical change explains the curing response.

Practical Guidance
For this cultivar, curing at 86°F with high relative humidity produced the best storage outcome. Higher temperatures caused internal breakdown during curing. High relative humidity was the decisive factor for effective curing at the optimal temperature.

Why This Source Matters
This is one of the earliest systematic biochemical investigations of what changes inside a fleshy storage root during curing. The pectic transformations and nitrogen redistribution documented here are not specific to sweet potato alone. They reflect broader physiological processes in starchy storage roots that can help frame dahlia curing cautiously. For growers, the finding that humidity was the decisive factor at the optimal curing temperature reinforces a principle that appears consistently across the curing literature.

Publication Type
Conference Proceedings Article

Full Citation
Van Leeuwen, P. J., & Trompert, J. P. T. (2005). Influence of drying conditions and storage temperature on desiccation and loss of tubers during storage and subsequent growth of Zantedeschia tubers. Acta Horticulturae, 673, 249–253.

Study System
Zantedeschia tubers (‘Mango’, ‘Treasure’, Z. albomaculata); postharvest drying and temperature-controlled storage until spring planting.

Experimental Context
Three-year factorial study examining the effects of postharvest drying and storage temperature on tuber losses, weight loss, and subsequent field performance.

Experimental Design
Tubers were dried for one week at 17°C with air speeds of 0, 0.2, or 2.0 m s⁻¹, followed by storage at 9, 13, 17, or 20°C. Storage losses, weight loss, and subsequent yield were measured across three years.

Key Results
No-air drying increased rot and calcification. Storage at 9°C caused the highest weight loss, lowest emergence, and lowest yield. Storage at 17 to 20°C minimized calcification and losses.

Mechanistic Insight
Drying promotes protective skin formation, which reduces infection and limits transpiration. Low storage temperatures increased desiccation and calcification in Zantedeschia, contrary to what might be assumed from general cold-storage principles.

Practical Guidance
Early drying with air circulation and storage above 13°C reduces tuber loss and improves subsequent yield in Zantedeschia. The absence of air movement during drying was associated with increased rot and structural losses.

Why This Source Matters
This study offers useful analog evidence for dahlia growers thinking about drying conditions and early storage temperatures. Zantedeschia is a monocot geophyte and not directly equivalent to dahlia, but the findings are informative points of comparison: no-air drying increased rot and calcification, and unexpectedly low storage temperatures increased rather than decreased losses. The practical implication for dahlia is cautiously analogous. Adequate air movement during initial drying and storage temperatures above the threshold for desiccation stress deserve attention.

Publication Type
Experimental Research Article

Full Citation
Picha, D. H. (1987). Carbohydrate changes in sweet potatoes during curing and storage. Journal of the American Society for Horticultural Science, 112(1), 89–92.

Study System
Sweet potato storage roots from four orange-flesh cultivars and two white-flesh cultivars.

Experimental Context
Evaluation of carbohydrate composition changes during curing and long-term storage under commercial sweet potato handling conditions.

Experimental Design
Roots were harvested in mid-October in two seasons. Carbohydrate composition was measured at harvest, after curing for 10 days at 32°C and 90% relative humidity, and at seven storage intervals over 46 weeks at 15.6°C and 90% relative humidity. Fructose, glucose, and sucrose were measured by high-performance liquid chromatography on a dry-weight basis.

Key Results
Sucrose was the major sugar at harvest in all cultivars and increased during curing in all six cultivars. In four orange-flesh cultivars, sucrose generally continued to increase during storage. In two white-flesh cultivars, sucrose decreased after curing before recovering after 14 weeks. Fructose and glucose increased during curing in all cultivars and continued to increase during storage in most. Total sugar increased during curing in all cultivars.

Mechanistic Insight
In orange-flesh cultivars, sucrose increase during storage was attributed to starch degradation via phosphorylase, because maltose was not detected and alcohol-insoluble solids decreased. In white-flesh cultivars, early storage involved net starch synthesis from sucrose, followed by a shift toward starch degradation after 14 weeks.

Practical Guidance
Curing and proper storage conditions can maintain sweet potato roots for up to a year without sprouting or serious decay. The greatest increase in sugar concentration generally occurred during curing. Carbohydrate behavior during storage is cultivar-dependent.

Why This Source Matters
Carbohydrate metabolism during curing and storage is relevant to understanding what is happening biochemically inside a fleshy storage root during the weeks after harvest. The finding that curing triggers a substantial increase in sugar concentration, and that this behavior differs by cultivar, is a useful frame for thinking about what dahlia tubers may be doing during the early storage period, even though the specific enzyme systems and cultivar responses will differ. This source complements KC-0073 by extending the biochemical picture from the curing window through long-term storage.

The Knowledge Card summaries in this collection were written by the author based on direct reading of the cited sources. AI tools assisted with retrieval, formatting, and assembly of this collection from the Dahlia Doctor research archive. All curatorial decisions, including source selection, topic organization, and editorial framing, were made by the author.