Planting date determination has long been a central agronomic decision in rain-fed crop production systems, directly influencing germination success, early biomass accumulation and yield formation (Shrestha et al., 2018). In a rain-fed country like Ghana, where crop production is highly dependent on seasonal rainfall, planting decisions are traditionally synchronized with the perceived onset of the rainy season. Unfortunately, the increasing variability in rainfall onset, the growing incidence of false starts and shortening of effective growing seasons have progressively undermined the reliability of these conventional calendars (Atiah et al., 2019; Amekudzi et al., 2015; Yorke and Omotosho, 2010). Consequently, planting-date uncertainty has emerged as a critical constraint to crop productivity across Ghana’s agroecological zones. With empirical evidence from literature, the rainfall onset in Ghana is no longer temporally stable, with delayed commencement, intermittent early season rainfall and prolonged dry spells being widely reported (Gbangou et al., 2020; Yengoh et al., 2010; Ampofo et al., 2024). These hydro-climatic shifts disproportionately affect the initial stages of crop establishment, when shallow root systems and high evaporative demand render seedlings particularly vulnerable to moisture stress (Asante et al., 2022). Not excluding mistimed planting, which can negatively impact crop establishment with serious consequences, by leading to early crop failure, also shortening the growing period, compressing vegetative growth and lessening grain filling in cereals. Mistimed planting also affects leguminous crops by disrupting both flowering and nodulation stage and in root and tuber crops, tuber development is constrained. (Boksoon et al., 2016; Shrestha et al., 2018; Atiah et al., 2019; Naveena et al., 2025).
       
Despite extensive agronomic and climatological studies addressing rainfall variability and crop performance in Ghana, planting dates are frequently treated as a static or secondary management variable. Many yield-response studies fail to explicitly account for planting-window dynamics, onset variability, or intra-season rainfall distribution (Fosu-Mensah  et al., 2019; Quagraine et al., 2017). Existing planting recommendations often rely on generalized calendars that inadequately capture district-level rainfall heterogeneity, shifting agroecological boundaries and evolving constraints related to labour availability, mechanisation and access to climate information (Yamba et al., 2023). This disconnect reduces the operational relevance of current planting-date advisories under increasingly variable climatic conditions.
       
Recent evidence further demonstrates that planting-date decisions operate as system-level variables rather than crop-specific choices. Planting timing alters intercrop competition, soil-nutrient uptake efficiency, pest and disease synchrony and labour bottlenecks, thereby shaping overall farming-system performance (Ampofo et al., 2024; Tanzubil, 2016; Shrestha et al., 2018). Delayed planting can therefore amplify production risks even in seasons with adequate cumulative rainfall (Yengoh et al., 2010). These interactions underscore the need for integrative analyses that explicitly link climatic signals, crop physiological responses and farming-system constraints.
       
This review aims to use previous publications’ empirical and modelling evidence which geared towards the inconsistencies in planting-date and their consequences on farming in the various agroecological zones of Ghana. Specifically, the review examines;
(i) Patterns of rainfall-onset variability and intra-season dry spells.
(ii) Crop-specific physiological responses to planting-date shifts.
(iii) System-level interactions affecting productivity under rain-fed farming systems.
       
By integrating climatic, agronomic and farming-system evidence, the review provides a structured assessment of how changing rainfall patterns are reshaping planting-window reliability and identifies pathways for improving planting-date recommendations in Ghana’s evolving agroecological landscape.
 
Review methodology
 
This study employed a structured narrative review approach to synthesise evidence on the relationships between rainfall variability, planting-date decisions, crop physiological responses and farming-system performance in Ghana. A narrative synthesis was selected because the reviewed studies differ considerably in research design, spatial scale and analytical methods, which limits the feasibility of quantitative meta-analysis.
       
Relevant literature was identified through systematic searches of major academic databases, including Web of Science, Scopus and Google Scholar. Search queries combined climatic and agronomic keywords such as rainfall onset, planting dates, dry spells, crop establishment, agroecological zones and Ghana, alongside crop-specific terms for cereals, legumes, root and tuber crops, vegetables and tree crops. Reference lists of key articles were also screened to identify additional relevant studies.
       
Studies were included if they (i) analysed rainfall onset, dry-spell behaviour, or growing-season characteristics relevant to Ghana; (ii) assessed crop responses explicitly linked to planting time or early-season moisture conditions; or (iii) examined farming-system interactions influenced by planting timing, including intercropping dynamics, soil nutrient interactions, pest and disease pressure, labour constraints, or advisory systems. Excluded studies were those lacking a clear connection between climatic conditions and planting-date decisions, focusing solely on irrigation-based systems, or providing insufficient spatial or temporal context for Ghanaian agroecological conditions.
       
Following selection, studies were thematically grouped according to agroecological zone, crop group and system-level interaction. Evidence was then synthesised to identify consistent patterns, divergences and emerging trends related to planting-window reliability under increasing climatic variability. Particular emphasis was placed on cross-zone comparisons, crop-specific sensitivities and the convergence of climatic and management constraints shaping planting decisions. This synthesis framework enabled the integration of diverse evidence into a coherent assessment of how planting-date variability influences crop production and farming-system performance in Ghana.
 
Rainfall onset behaviour and intra-season variability in ghana
 
Rainfall onset remains the principal climatic signal guiding planting decisions in Ghana; however, its reliability has deteriorated markedly over recent decades. Multiple studies document increasing delays in the commencement of the rainy season, heightened interannual variability and frequent early-season rainfall interruptions across all agroecological zones (Mensah-Brako  et al., 2026) (Fig 1). These changes have direct agronomic implications because the success of crop establishment depends less on total seasonal rainfall than on the timing, continuity and stability of early-season precipitation. Even though, in the Guinea and Sudan Savannah zones, rainfall onset is unimodal but increasingly characterised by long dry spells and reduced numbers of rainy days following initial precipitation events (Ampofo et al., 2024; Yengoh et al., 2010), recently the commonly reported rainfall pattern by various studies has been false rainfall starts, defined as early-season rainfall. This rainfall pattern is insufficient to sustain seedling establishment, leading to frequent crop establishment failure when planting occurs prematurely (Gbangou et al., 2020). As a result, farmers delay planting until rainfall patterns stabilise, often shortening the effective growing season and exposing crops to terminal moisture stress later in the cycle.


       
Bimodal rainfall zones, including the Forest Savannah Transition and Coastal Savannah, exhibit distinct but equally problematic onset dynamics. While these zones historically supported two reliable planting seasons, recent evidence indicates increasing overlap, weakening separation between major and minor seasons and oscillation in onset dates between March and May (Atiah et al., 2019; Quagraine et al., 2017; Gbangou et al., 2020). Such variability complicates planting decisions for crops traditionally aligned with specific seasonal windows, increasing the probability of mismatch between crop growth stages and rainfall availability.
       
Even though, across zones intra-season dry spells represent a dominant constraint even in years with near-normal cumulative rainfall, prolonged consecutive dry days during the first three to four weeks after planting significantly increase seedling mortality and reduce early biomass accumulation, particularly for cereals and legumes with shallow root systems (Yengoh et al., 2010; Ampofo et al., 2024). These effects are compounded by rising temperatures and high evaporative demand, which intensify moisture stress during early growth stages (Ankrah et al., 2023). Recent analyses further indicate that rainfall variability is not spatially static. Southward shifts of the Guinea and Sudan Savannah agroecological boundaries reflect broader climatic reorganisation, altering historical rainfall crop relationships and invalidating long-established planting calendars (Adaawen, 2021). Consequently, planting-window reliability is increasingly context-specific, dependent on local onset thresholds, soil moisture retention and the capacity of farmers to absorb early-season risk (Fig 2).


       
Collectively, these findings demonstrate that rainfall onset in Ghana can no longer be treated as a fixed temporal reference. Instead, it represents a probabilistic signal with significant uncertainty, necessitating planting strategies that account for onset stability, dry-spell risk and zone-specific rainfall behaviour rather than adherence to static calendar dates.
 
Crop-specific sensitivity to planting dates
 
Crop responses to planting dates in Ghana are governed by interactions between rainfall availability during early growth stages and crop-specific physiological requirements. Evidence across agroecological zones consistently shows that mismatches between planting timing and early-season moisture conditions lead to significant yield penalties, though the magnitude and mechanisms vary by crop group.
       
To facilitate clearer comparison across crop groups, the major physiological responses and risks associated with early and late planting are summarised in (Table 1), which synthesises evidence from agronomic field studies conducted across Ghana’s agroecological zones.


       
Cereals, particularly maize, sorghum and millet, exhibit strong sensitivity to delayed planting. Early planting immediately after stable rainfall onset enhances radiation interception, prolongs vegetative growth and supports adequate grain-filling duration (Boksoon et al., 2016; Shrestha et al., 2018). In contrast, delayed planting shortens thermal accumulation and exposes crops to terminal moisture stress and high temperatures, resulting in reduced kernel number and grain weight, especially in the Guinea and Transition zones (Ampofo et al., 2024; Fosu-Mensah  et al., 2019). In bimodal rainfall zones, premature planting during unstable early rains can also increase establishment failure due to waterlogging and rainfall discontinuity (Atiah et al., 2019).
       
Legumes, including cowpea, soybean and groundnut, are particularly vulnerable to planting-date mismatches during flowering and pod-filling stages. Optimal planting ensures alignment between reproductive development and periods of relatively stable moisture, facilitating nodulation and nitrogen fixation (Abdul-Aziz  et al., 2025; Fakhr et al., 2020). Early planting in high-rainfall environments increases disease incidence and flower abortion, while delayed planting in unimodal zones exposes legumes to dry spells during flowering, leading to poor pod set and reduced yields (Atiah et al., 2019; Ampofo et al., 2024).
       
Root and tuber crops, such as cassava, yam and cocoyam, require extended periods of soil moisture availability to support canopy development and tuber initiation. Early planting in forest and transition zones promotes root establishment and vegetative growth; however, excessive early-season rainfall can increase rot and disease incidence (Issaka et al., 2012; Afele et al., 2021). Delayed planting shortens the vegetative phase, restricts canopy expansion and limits assimilate partitioning to storage organs, resulting in reduced tuber size and biomass (Kim et al., 2012) (Atiah et al., 2019).
       
Vegetable crops, including tomato, pepper, onion and cabbage, display narrow optimal planting windows due to their sensitivity to both excess and deficit moisture. Early planting during periods of high rainfall increases waterlogging, leaf diseases and fruit drop, particularly in forest and transition zones (Barickman et al., 2019; Atiah et al., 2019). Late planting, especially in the northern savannahs, exposes crops to extreme temperatures and moisture stress during reproductive stages, reducing marketable yield (Ampofo et al., 2024).
       
Tree crops, notably cocoa and cashew, depend on timely planting early in the rainy season to ensure seedling establishment before the onset of dry spells. Delayed planting exposes seedlings to prolonged moisture deficits and increases mortality rates, while excessive early-season rainfall can restrict field operations and reduce survival in poorly drained soils (Issaka et al., 2012; Afele et al., 2021).
       
Overall, the reviewed evidence demonstrates that planting-date sensitivity is crop-specific but consistently mediated by early-season moisture stability. Across crop groups, delayed planting increases exposure to terminal drought, shortens effective growth periods and amplifies production risk, reinforcing the need for planting recommendations that account for both crop physiology and rainfall onset behaviour.
 
Farming-system interactions influenced by planting dates
 
Planting-date decisions in Ghana operate beyond individual crop performance and exert system-wide effects on resource use, crop interactions and risk exposure within smallholder farming systems (Fig 3). Evidence across agroecological zones demonstrates that poorly synchronized planting amplifies inefficiencies in intercropping arrangements, nutrient use, pest and disease dynamics and labour allocation (Aduhene-Chnbuah  et al., 2025; Shrestha et al., 2018; Ampofo et al., 2024). However, intercropping systems which are widely practiced to manage risk and enhance resource-use efficiency, on the other hand are highly sensitive to planting-time coordination among component crops. Simultaneous or appropriately staggered planting improves canopy complementarity, soil cover and light interception, thereby reducing weed pressure and moisture loss (Tanzubil, 2016). In contrast, delayed or staggered planting driven by uncertain rainfall onset increases interspecific competition for moisture and nutrients, often favouring early-emerging crops and reducing overall system productivity (Shrestha et al., 2018).


       
Soil fertility management and nutrient uptake efficiency are also tightly linked to planting timing. Early planting following stable rainfall onset enhances nutrient dissolution and root soil contact, particularly for nitrogen and phosphorus in rain-fed systems (Issaka et al., 2012). Delayed planting, especially in degraded or low-organic-matter soils, reduces nutrient-use efficiency as shortened growth periods limit root expansion and nutrient assimilation, resulting in lower biomass accumulation and yield (Fosu-Mensah  et al., 2019). These effects are more pronounced in northern savannah zones where soil moisture retention is inherently limited.
       
Planting dates further influence pest and disease dynamics through crop climate synchrony. Early planting can enable crops to escape peak pest populations and disease-favourable conditions, whereas delayed planting often aligns vulnerable growth stages with heightened pest pressure and humidity (Atiah et al., 2019; Afele et al., 2021). In vegetable production systems, mistimed planting increases disease incidence and pesticide reliance, raising production costs and environmental risk. Also, availability of labour and mechanisation access impose additional constraints on planting-date flexibility, this is because in smallholder systems, rainfall uncertainty frequently leads to labour bottlenecks as farmers delay planting until rainfall stabilises, resulting in simultaneous demand for land preparation and sowing (Yamba et al., 2023). Limited mechanisation exacerbates these delays, particularly in northern Ghana, where timely land preparation is critical due to shorter growing seasons (Ampofo et al., 2024). Consequently, climatic uncertainty interacts with socio-economic constraints to compound planting delays and yield losses.
       
Collectively, the evidence indicates that planting dates function as a structural driver of farming-system performance rather than an isolated management choice. Improving planting-date recommendations therefore requires integration of climatic signals with system-level realities, including cropping patterns, soil constraints, pest dynamics and labour organisation.
       
The evidence synthesised in this review demonstrates that planting-date reliability in Ghana is increasingly undermined by the combined effects of rainfall-onset variability, intra-season dry spells and shifting agroecological boundaries (Fig 4). Across all zones, planting decisions based on historical calendars no longer consistently align crop establishment with stable moisture availability, exposing crops to early-season failure or terminal stress despite near-normal seasonal rainfall totals (Atiah et al., 2021; Kumar et al., 2024).


       
However, looking from a climatic perspective, rainfall onset has transitioned from a relatively predictable seasonal marker to a probabilistic signal characterised by false starts and spatial heterogeneity (Gbangou et al., 2020; Agoungbome et al., 2025). This uncertainty disproportionately affects early crop growth stages, where moisture stress irreversibly constrains canopy development and yield potential (Kelly et al., 2025). The southward shift of savannah agroecological conditions further disrupts long-established rainfall crop relationships, rendering zone-based planting calendars increasingly obsolete (Yamba et al., 2023).
       
Nonetheless, crop-specific analyses reveal that while sensitivity to planting dates varies by crop group, delayed or poorly timed planting consistently shortens effective growth periods, reduces assimilate accumulation and increases exposure to reproductive-stage stress across cereals, legumes, root and tuber crops, vegetables and tree crops (Shrestha et al., 2018; Boksoon et al., 2016; Afele et al., 2021). Consequently, these responses confirm that planting dates act as a primary yield determinant under rain-fed conditions, mediating how crops interact with rainfall variability rather than merely responding to total precipitation.
       
Also approaching from a farming-system level, planting-date uncertainty propagates through intercropping performance, nutrient-use efficiency, pest and disease dynamics and labour organisation (Tanzubil, 2016; Fosu-Mensah  et al., 2019; Ampofo et al., 2024). Delayed planting triggered by rainfall instability often leads to synchronised labour demand, increased pest pressure and reduced system resilience, particularly in smallholder contexts with limited mechanisation and advisory support (Amankwaa-Yeboah  et al., 2024).
       
Collectively, these findings suggest that effective adaptation cannot rely solely on fixed planting recommendations. Instead, adaptive pathways must integrate rainfall-onset monitoring, crop-specific sensitivity thresholds and system-level constraints. Approaches that combine seasonal climate information, flexible planting windows and locally contextualised decision support are better suited to managing planting risk under Ghana’s evolving climatic conditions (Atiah et al., 2019; Ampofo et al., 2024). Such integration represents a critical step toward enhancing climate resilience and stabilising crop productivity across agroecological zones.
       
Broader climatic drivers influencing planting-window variability are synthesised in (Table 2) highlighting the major mechanisms through which climate change is altering planting decisions in Ghana.

Planting-date reliability in Ghana is increasingly threatened by rainfall variability, false onset events, and shifting agroecological conditions. This review demonstrates that delayed or poorly synchronized planting negatively affects crop establishment, growth duration, and yield formation across cereals, legumes, root and tuber crops, vegetables, and tree crops. The effects extend beyond individual crops to influence nutrient-use efficiency, pest dynamics, intercropping performance, and labour organization within smallholder farming systems. Evidence further shows that traditional planting calendars are becoming less dependable under changing climatic conditions. Improving planting-date decisions therefore requires flexible, climate-informed approaches that integrate rainfall monitoring, crop-specific sensitivity, and local farming constraints. Strengthening climate information services and adaptive advisory systems will be essential for enhancing resilience and sustaining rain-fed agricultural productivity across Ghana’s agroecological zones.

The present study was supported by my friends and thank to all who made any significant input to the success of this study. Thank you all.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.