diff --git a/herbapi-api/src/db/cultivars.rs b/herbapi-api/src/db/cultivars.rs
index 25a02a6..666cd25 100644
--- a/herbapi-api/src/db/cultivars.rs
+++ b/herbapi-api/src/db/cultivars.rs
@@ -127,7 +127,10 @@ pub async fn create(pool: &PgPool, req: &CreateCultivar) -> Result<Cultivar> {
          min_light_hours_day, optimal_light_hours_day, greenhouse_min_temp_c,
          indoor_season_extension_weeks, ventilation_requirement, heating_required,
          indoor_sowing_months, direct_sowing_months, transplanting_months, glasshouse_months,
-         harvesting_months, succession_planting_days, planting_notes,
+         harvesting_months,
+         indoor_sowing_weeks, direct_sowing_weeks, transplanting_weeks, glasshouse_weeks,
+         harvesting_weeks,
+         succession_planting_days, planting_notes,
          propagation_methods, cutting_season, rootstock_species_id,
          years_to_first_harvest, productive_lifespan_years,
          expected_yield_kg_per_m2, yield_unit, expected_yield_value,
@@ -137,7 +140,7 @@ pub async fn create(pool: &PgPool, req: &CreateCultivar) -> Result<Cultivar> {
          VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,
                  $21,$22,$23,$24,$25,$26,$27,$28,$29,$30,$31::frost_tolerance,$32,$33,$34,$35,$36,$37,
                  $38,$39,$40,$41,$42,$43,$44,$45,$46,$47,$48,$49,$50,$51,$52,$53,$54,$55,$56,
-                 $57,$58,$59,$60,$61,$62,$63)
+                 $57,$58,$59,$60,$61,$62,$63,$64,$65,$66,$67,$68)
          RETURNING *"
     )
     .bind(id).bind(&slug).bind(req.species_id).bind(&req.name)
@@ -155,7 +158,11 @@ pub async fn create(pool: &PgPool, req: &CreateCultivar) -> Result<Cultivar> {
     .bind(req.indoor_season_extension_weeks).bind(&req.ventilation_requirement).bind(req.heating_required)
     .bind(&req.indoor_sowing_months).bind(&req.direct_sowing_months)
     .bind(&req.transplanting_months).bind(&req.glasshouse_months)
-    .bind(&req.harvesting_months).bind(req.succession_planting_days).bind(&req.planting_notes)
+    .bind(&req.harvesting_months)
+    .bind(&req.indoor_sowing_weeks).bind(&req.direct_sowing_weeks)
+    .bind(&req.transplanting_weeks).bind(&req.glasshouse_weeks)
+    .bind(&req.harvesting_weeks)
+    .bind(req.succession_planting_days).bind(&req.planting_notes)
     .bind(&req.propagation_methods).bind(&req.cutting_season).bind(req.rootstock_species_id)
     .bind(req.years_to_first_harvest).bind(req.productive_lifespan_years)
     .bind(req.expected_yield_kg_per_m2).bind(&req.yield_unit).bind(req.expected_yield_value)
@@ -192,13 +199,16 @@ pub async fn update(pool: &PgPool, id: Uuid, req: &CreateCultivar) -> Result<Cul
          min_light_hours_day=$32, optimal_light_hours_day=$33, greenhouse_min_temp_c=$34,
          indoor_season_extension_weeks=$35, ventilation_requirement=$36, heating_required=$37,
          indoor_sowing_months=$38, direct_sowing_months=$39, transplanting_months=$40,
-         glasshouse_months=$41, harvesting_months=$42, succession_planting_days=$43,
-         planting_notes=$44, propagation_methods=$45, cutting_season=$46,
-         rootstock_species_id=$47, years_to_first_harvest=$48, productive_lifespan_years=$49,
-         expected_yield_kg_per_m2=$50, yield_unit=$51, expected_yield_value=$52,
-         harvest_window_days=$53, storage_method=$54, shelf_life_days=$55, cold_storage_days=$56,
-         pollination_group=$57, self_fertile=$58, rootstock_compatibility=$59,
-         wikidata_qid=$60, gbif_id=$61, pfaf_url=$62, source_urls=$63, updated_at=NOW()
+         glasshouse_months=$41, harvesting_months=$42,
+         indoor_sowing_weeks=$43, direct_sowing_weeks=$44, transplanting_weeks=$45,
+         glasshouse_weeks=$46, harvesting_weeks=$47,
+         succession_planting_days=$48,
+         planting_notes=$49, propagation_methods=$50, cutting_season=$51,
+         rootstock_species_id=$52, years_to_first_harvest=$53, productive_lifespan_years=$54,
+         expected_yield_kg_per_m2=$55, yield_unit=$56, expected_yield_value=$57,
+         harvest_window_days=$58, storage_method=$59, shelf_life_days=$60, cold_storage_days=$61,
+         pollination_group=$62, self_fertile=$63, rootstock_compatibility=$64,
+         wikidata_qid=$65, gbif_id=$66, pfaf_url=$67, source_urls=$68, updated_at=NOW()
          WHERE id=$1 RETURNING *"
     )
     .bind(id).bind(&slug).bind(req.species_id).bind(&req.name)
@@ -216,7 +226,11 @@ pub async fn update(pool: &PgPool, id: Uuid, req: &CreateCultivar) -> Result<Cul
     .bind(req.indoor_season_extension_weeks).bind(&req.ventilation_requirement).bind(req.heating_required)
     .bind(&req.indoor_sowing_months).bind(&req.direct_sowing_months)
     .bind(&req.transplanting_months).bind(&req.glasshouse_months)
-    .bind(&req.harvesting_months).bind(req.succession_planting_days).bind(&req.planting_notes)
+    .bind(&req.harvesting_months)
+    .bind(&req.indoor_sowing_weeks).bind(&req.direct_sowing_weeks)
+    .bind(&req.transplanting_weeks).bind(&req.glasshouse_weeks)
+    .bind(&req.harvesting_weeks)
+    .bind(req.succession_planting_days).bind(&req.planting_notes)
     .bind(&req.propagation_methods).bind(&req.cutting_season).bind(req.rootstock_species_id)
     .bind(req.years_to_first_harvest).bind(req.productive_lifespan_years)
     .bind(req.expected_yield_kg_per_m2).bind(&req.yield_unit).bind(req.expected_yield_value)
diff --git a/herbapi-api/src/db/models.rs b/herbapi-api/src/db/models.rs
index a79d4b7..300cb63 100644
--- a/herbapi-api/src/db/models.rs
+++ b/herbapi-api/src/db/models.rs
@@ -250,6 +250,11 @@ pub struct Cultivar {
     pub transplanting_months: Option<Vec<i32>>,
     pub glasshouse_months: Option<Vec<i32>>,
     pub harvesting_months: Option<Vec<i32>>,
+    pub indoor_sowing_weeks: Option<Vec<i32>>,
+    pub direct_sowing_weeks: Option<Vec<i32>>,
+    pub transplanting_weeks: Option<Vec<i32>>,
+    pub glasshouse_weeks: Option<Vec<i32>>,
+    pub harvesting_weeks: Option<Vec<i32>>,
     pub succession_planting_days: Option<i32>,
     pub planting_notes: Option<String>,
     pub propagation_methods: Option<Vec<String>>,
@@ -318,6 +323,11 @@ pub struct CreateCultivar {
     pub transplanting_months: Option<Vec<i32>>,
     pub glasshouse_months: Option<Vec<i32>>,
     pub harvesting_months: Option<Vec<i32>>,
+    pub indoor_sowing_weeks: Option<Vec<i32>>,
+    pub direct_sowing_weeks: Option<Vec<i32>>,
+    pub transplanting_weeks: Option<Vec<i32>>,
+    pub glasshouse_weeks: Option<Vec<i32>>,
+    pub harvesting_weeks: Option<Vec<i32>>,
     pub succession_planting_days: Option<i32>,
     pub planting_notes: Option<String>,
     pub propagation_methods: Option<Vec<String>>,
diff --git a/herbapi-ui/assets/herbapi.css b/herbapi-ui/assets/herbapi.css
index eb2af0f..ed39227 100644
--- a/herbapi-ui/assets/herbapi.css
+++ b/herbapi-ui/assets/herbapi.css
@@ -468,6 +468,86 @@ tr:hover td {
     background: var(--cal-harvest);
 }
 
+/* 52-Week Planting Calendar */
+
+.week-calendar {
+    padding: 0.5rem;
+    border: none;
+    box-shadow: none;
+    background: transparent;
+}
+
+.wcal-month-row {
+    display: grid;
+    grid-template-columns: 100px repeat(52, 1fr);
+    gap: 1px;
+    margin-bottom: 2px;
+}
+
+.wcal-month-header {
+    font-size: 0.7rem;
+    font-weight: 600;
+    color: var(--text-muted);
+    text-align: center;
+    padding: 0.2rem 0;
+    border-bottom: 1px solid var(--border);
+}
+
+.wcal-label {
+    font-size: 0.75rem;
+    padding: 0.15rem 0.4rem;
+    white-space: nowrap;
+    display: flex;
+    align-items: center;
+}
+
+.wcal-row {
+    display: grid;
+    grid-template-columns: 100px repeat(52, 1fr);
+    gap: 1px;
+    margin-bottom: 1px;
+}
+
+.wcal-cell {
+    height: 18px;
+    border-radius: 2px;
+    background: #f0f0f0;
+}
+
+.wcal-cell.active.cal-indoor  { background: var(--cal-indoor); }
+.wcal-cell.active.cal-direct  { background: var(--cal-direct); }
+.wcal-cell.active.cal-transplant { background: var(--cal-transplant); }
+.wcal-cell.active.cal-glass   { background: var(--cal-glass); }
+.wcal-cell.active.cal-harvest { background: var(--cal-harvest); }
+
+.wcal-legend {
+    display: flex;
+    gap: 1rem;
+    margin-top: 0.5rem;
+    padding-left: 100px;
+    flex-wrap: wrap;
+}
+
+.wcal-legend-item {
+    display: flex;
+    align-items: center;
+    gap: 0.3rem;
+    font-size: 0.7rem;
+    color: var(--text-muted);
+}
+
+.wcal-legend-swatch {
+    width: 14px;
+    height: 10px;
+    border-radius: 2px;
+}
+
+.wcal-legend-swatch.cal-indoor  { background: var(--cal-indoor); }
+.wcal-legend-swatch.cal-direct  { background: var(--cal-direct); }
+.wcal-legend-swatch.cal-transplant { background: var(--cal-transplant); }
+.wcal-legend-swatch.cal-glass   { background: var(--cal-glass); }
+.wcal-legend-swatch.cal-harvest { background: var(--cal-harvest); }
+
 /* Pagination */
 
 .pagination {
diff --git a/herbapi-ui/src/components/planting_calendar.rs b/herbapi-ui/src/components/planting_calendar.rs
index 1e72d5e..9958108 100644
--- a/herbapi-ui/src/components/planting_calendar.rs
+++ b/herbapi-ui/src/components/planting_calendar.rs
@@ -1,51 +1,105 @@
 use dioxus::prelude::*;
 
-const MONTH_LABELS: [&str; 12] = ["J", "F", "M", "A", "M", "J", "J", "A", "S", "O", "N", "D"];
+/// Month boundaries as week ranges (approximate ISO weeks).
+/// Jan=1-4, Feb=5-8, Mar=9-13, Apr=14-17, May=18-22, Jun=23-26,
+/// Jul=27-30, Aug=31-35, Sep=36-39, Oct=40-44, Nov=45-48, Dec=49-52
+const MONTH_WEEK_RANGES: [(u8, u8); 12] = [
+    (1, 4), (5, 8), (9, 13), (14, 17), (18, 22), (23, 26),
+    (27, 30), (31, 35), (36, 39), (40, 44), (45, 48), (49, 52),
+];
+
+const MONTH_LABELS: [&str; 12] = [
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
+];
+
+/// Expand month data (1-12) into week numbers (1-52) for fallback.
+fn months_to_weeks(months: &Option<Vec<i32>>) -> Option<Vec<i32>> {
+    let m = months.as_ref()?;
+    if m.is_empty() { return None; }
+    let mut weeks = Vec::new();
+    for &month in m {
+        if month >= 1 && month <= 12 {
+            let (start, end) = MONTH_WEEK_RANGES[(month - 1) as usize];
+            for w in start..=end {
+                weeks.push(w as i32);
+            }
+        }
+    }
+    weeks.sort();
+    weeks.dedup();
+    Some(weeks)
+}
+
+/// Resolve: prefer week data, fall back to expanding month data.
+fn resolve_weeks(weeks: &Option<Vec<i32>>, months: &Option<Vec<i32>>) -> Option<Vec<i32>> {
+    if let Some(w) = weeks {
+        if !w.is_empty() {
+            return Some(w.clone());
+        }
+    }
+    months_to_weeks(months)
+}
 
 #[component]
 pub fn PlantingCalendar(
-    indoor_sowing: Option<Vec<i32>>,
-    direct_sowing: Option<Vec<i32>>,
-    transplanting: Option<Vec<i32>>,
-    glasshouse: Option<Vec<i32>>,
-    harvesting: Option<Vec<i32>>,
+    indoor_sowing_months: Option<Vec<i32>>,
+    direct_sowing_months: Option<Vec<i32>>,
+    transplanting_months: Option<Vec<i32>>,
+    glasshouse_months: Option<Vec<i32>>,
+    harvesting_months: Option<Vec<i32>>,
+    indoor_sowing_weeks: Option<Vec<i32>>,
+    direct_sowing_weeks: Option<Vec<i32>>,
+    transplanting_weeks: Option<Vec<i32>>,
+    glasshouse_weeks: Option<Vec<i32>>,
+    harvesting_weeks: Option<Vec<i32>>,
 ) -> Element {
-    let rows: Vec<(&str, &str, &Option<Vec<i32>>)> = vec![
-        ("Indoor Sowing", "cal-indoor", &indoor_sowing),
-        ("Direct Sowing", "cal-direct", &direct_sowing),
-        ("Transplanting", "cal-transplant", &transplanting),
-        ("Glasshouse", "cal-glass", &glasshouse),
-        ("Harvesting", "cal-harvest", &harvesting),
+    let rows: Vec<(&str, &str, Option<Vec<i32>>)> = vec![
+        ("Indoor Sowing", "cal-indoor", resolve_weeks(&indoor_sowing_weeks, &indoor_sowing_months)),
+        ("Direct Sowing", "cal-direct", resolve_weeks(&direct_sowing_weeks, &direct_sowing_months)),
+        ("Transplanting", "cal-transplant", resolve_weeks(&transplanting_weeks, &transplanting_months)),
+        ("Glasshouse", "cal-glass", resolve_weeks(&glasshouse_weeks, &glasshouse_months)),
+        ("Harvesting", "cal-harvest", resolve_weeks(&harvesting_weeks, &harvesting_months)),
     ];
 
-    // Check if any data exists
-    let has_data = rows.iter().any(|(_, _, months)| months.is_some());
+    let has_data = rows.iter().any(|(_, _, w)| w.is_some());
     if !has_data {
         return rsx! { p { class: "empty", "No planting calendar data." } };
     }
 
     rsx! {
-        div { class: "planting-calendar",
-            // Header row with month labels
-            div { class: "cal-row cal-header",
-                div { class: "cal-label" }
-                for label in MONTH_LABELS.iter() {
-                    div { class: "cal-cell", "{label}" }
+        div { class: "planting-calendar week-calendar",
+            // Month header spanning groups of weeks
+            div { class: "wcal-month-row",
+                div { class: "wcal-label" }
+                for (i, label) in MONTH_LABELS.iter().enumerate() {
+                    {
+                        let (start, end) = MONTH_WEEK_RANGES[i];
+                        let span = (end - start + 1) as usize;
+                        rsx! {
+                            div {
+                                class: "wcal-month-header",
+                                style: "grid-column: span {span};",
+                                "{label}"
+                            }
+                        }
+                    }
                 }
             }
             // Data rows
-            for (name, class, months) in rows.iter() {
-                if months.is_some() {
-                    div { class: "cal-row",
-                        div { class: "cal-label", "{name}" }
-                        for month in 1..=12i32 {
+            for (name, class, weeks) in rows.iter() {
+                if weeks.is_some() {
+                    div { class: "wcal-row",
+                        div { class: "wcal-label", "{name}" }
+                        for week in 1..=52i32 {
                             {
-                                let active = months.as_ref()
-                                    .map(|m| m.contains(&month))
+                                let active = weeks.as_ref()
+                                    .map(|w| w.contains(&week))
                                     .unwrap_or(false);
                                 rsx! {
                                     div {
-                                        class: if active { format!("cal-cell {class} active") } else { "cal-cell".to_string() },
+                                        class: if active { format!("wcal-cell {class} active") } else { "wcal-cell".to_string() },
+                                        title: "W{week}",
                                     }
                                 }
                             }
@@ -53,6 +107,29 @@ pub fn PlantingCalendar(
                     }
                 }
             }
+            // Legend
+            div { class: "wcal-legend",
+                div { class: "wcal-legend-item",
+                    div { class: "wcal-legend-swatch cal-indoor" }
+                    span { "Indoor Sowing" }
+                }
+                div { class: "wcal-legend-item",
+                    div { class: "wcal-legend-swatch cal-direct" }
+                    span { "Direct Sowing" }
+                }
+                div { class: "wcal-legend-item",
+                    div { class: "wcal-legend-swatch cal-transplant" }
+                    span { "Transplanting" }
+                }
+                div { class: "wcal-legend-item",
+                    div { class: "wcal-legend-swatch cal-glass" }
+                    span { "Glasshouse" }
+                }
+                div { class: "wcal-legend-item",
+                    div { class: "wcal-legend-swatch cal-harvest" }
+                    span { "Harvesting" }
+                }
+            }
         }
     }
 }
diff --git a/herbapi-ui/src/pages/cultivars.rs b/herbapi-ui/src/pages/cultivars.rs
index 12d66de..7974e55 100644
--- a/herbapi-ui/src/pages/cultivars.rs
+++ b/herbapi-ui/src/pages/cultivars.rs
@@ -4,6 +4,7 @@ use uuid::Uuid;
 
 use crate::api;
 use crate::app::{Lang, Route};
+use crate::components::planting_calendar::PlantingCalendar;
 use crate::components::table_controls::*;
 use crate::i18n::{pick_desc, pick_name};
 
@@ -378,6 +379,25 @@ pub fn CultivarDetail(slug: String) -> Element {
                             p { class: "name-common", "{common_name}" }
                         }
 
+                        // Week-based planting calendar (full width)
+                        div { class: "detail-card", style: "margin-top: 1.25rem;",
+                            div { class: "detail-card-header", "Planting Calendar" }
+                            div { style: "padding: 0.75rem;",
+                                PlantingCalendar {
+                                    indoor_sowing_months: c.indoor_sowing_months.clone(),
+                                    direct_sowing_months: c.direct_sowing_months.clone(),
+                                    transplanting_months: c.transplanting_months.clone(),
+                                    glasshouse_months: c.glasshouse_months.clone(),
+                                    harvesting_months: c.harvesting_months.clone(),
+                                    indoor_sowing_weeks: c.indoor_sowing_weeks.clone(),
+                                    direct_sowing_weeks: c.direct_sowing_weeks.clone(),
+                                    transplanting_weeks: c.transplanting_weeks.clone(),
+                                    glasshouse_weeks: c.glasshouse_weeks.clone(),
+                                    harvesting_weeks: c.harvesting_weeks.clone(),
+                                }
+                            }
+                        }
+
                         div { class: "detail-row",
                             // === LEFT COLUMN ===
                             div { class: "detail-col",
diff --git a/herbapi-ui/src/types.rs b/herbapi-ui/src/types.rs
index 012a0bf..dfc8542 100644
--- a/herbapi-ui/src/types.rs
+++ b/herbapi-ui/src/types.rs
@@ -117,6 +117,11 @@ pub struct Cultivar {
     pub transplanting_months: Option<Vec<i32>>,
     pub glasshouse_months: Option<Vec<i32>>,
     pub harvesting_months: Option<Vec<i32>>,
+    pub indoor_sowing_weeks: Option<Vec<i32>>,
+    pub direct_sowing_weeks: Option<Vec<i32>>,
+    pub transplanting_weeks: Option<Vec<i32>>,
+    pub glasshouse_weeks: Option<Vec<i32>>,
+    pub harvesting_weeks: Option<Vec<i32>>,
     pub succession_planting_days: Option<i32>,
     pub planting_notes: Option<String>,
     pub propagation_methods: Option<Vec<String>>,