diff --git a/herbapi-ui/assets/herbapi.css b/herbapi-ui/assets/herbapi.css
index 24efca2..324201e 100644
--- a/herbapi-ui/assets/herbapi.css
+++ b/herbapi-ui/assets/herbapi.css
@@ -1197,6 +1197,28 @@ td.placeholder {
     text-decoration: underline;
 }
 
+/* Species-fallback estimated values */
+
+.estimated-value {
+    color: var(--accent);
+    font-style: italic;
+}
+
+.estimated-tag {
+    font-size: 0.7rem;
+    color: var(--text-muted);
+    margin-left: 0.4rem;
+    opacity: 0.7;
+}
+
+.species-fallback-note {
+    font-size: 0.8rem;
+    color: var(--text-muted);
+    font-style: italic;
+    margin-top: 1.25rem;
+    opacity: 0.7;
+}
+
 /* Responsive */
 
 @media (max-width: 768px) {
diff --git a/herbapi-ui/src/pages/cultivars.rs b/herbapi-ui/src/pages/cultivars.rs
index ba48d6a..ee25959 100644
--- a/herbapi-ui/src/pages/cultivars.rs
+++ b/herbapi-ui/src/pages/cultivars.rs
@@ -70,6 +70,27 @@ fn opt_vec_str(val: &Option<Vec<String>>) -> String {
     }
 }
 
+/// Infer a light requirement string from a species plant_layer value.
+fn infer_light_from_layer(layer: &Option<String>) -> Option<String> {
+    match layer.as_deref() {
+        Some(l) => {
+            let lower = l.to_lowercase();
+            if lower.contains("canopy") || lower.contains("tall tree") {
+                Some("Full sun".to_string())
+            } else if lower.contains("understory") || lower.contains("small tree") || lower.contains("shrub") {
+                Some("Partial shade".to_string())
+            } else if lower.contains("ground") || lower.contains("creep") {
+                Some("Shade tolerant".to_string())
+            } else if lower.contains("herb") || lower.contains("climber") || lower.contains("vine") {
+                Some("Full sun to partial shade".to_string())
+            } else {
+                None
+            }
+        }
+        None => None,
+    }
+}
+
 const STORAGE_KEY_COLS: &str = "herbapi_cultivars_cols";
 const STORAGE_KEY_PP: &str = "herbapi_cultivars_pp";
 
@@ -385,6 +406,33 @@ pub fn CultivarDetail(slug: String) -> Element {
                     let min_light_h = opt_f64_suffix(c.min_light_hours_day, " h");
                     let opt_light_h = opt_f64_suffix(c.optimal_light_hours_day, " h");
 
+                    // --- Species fallback values ---
+                    // When a cultivar field is empty, we show species-level
+                    // data styled as an estimation.
+                    let (sp_frost_fb, sp_light_fb, sp_drought_fb, sp_usda_fb) = {
+                        let sp_read = species_data.read();
+                        match &*sp_read {
+                            Some(Some(sp)) => {
+                                let frost = sp.hardiness_zone_usda.as_ref()
+                                    .filter(|s| !s.is_empty())
+                                    .map(|z| format!("USDA Zone {z}"));
+                                let light = infer_light_from_layer(&sp.plant_layer);
+                                let drought = sp.drought_tolerance.clone()
+                                    .filter(|s| !s.is_empty());
+                                let usda = sp.hardiness_zone_usda.clone()
+                                    .filter(|s| !s.is_empty());
+                                (frost, light, drought, usda)
+                            }
+                            _ => (None, None, None, None),
+                        }
+                    };
+                    let has_any_fallback =
+                        (frost_tol == "\u{2014}" && sp_frost_fb.is_some())
+                        || (light_req == "\u{2014}" && sp_light_fb.is_some())
+                        || (light == "\u{2014}" && sp_light_fb.is_some())
+                        || sp_drought_fb.is_some()
+                        || sp_usda_fb.is_some();
+
                     // Species image: prefer primary from images API, else primary_image_key
                     let sp_primary_img: Option<crate::types::Image> = {
                         let imgs = species_images.read();
@@ -673,7 +721,16 @@ pub fn CultivarDetail(slug: String) -> Element {
                                             }
                                             tr {
                                                 th { "Light Requirement" }
-                                                td { class: if light_req == "\u{2014}" { "placeholder" } else { "" }, "{light_req}" }
+                                                if light_req != "\u{2014}" {
+                                                    td { "{light_req}" }
+                                                } else if let Some(ref fb) = sp_light_fb {
+                                                    td {
+                                                        span { class: "estimated-value", "{fb}" }
+                                                        span { class: "estimated-tag", "~ species" }
+                                                    }
+                                                } else {
+                                                    td { class: "placeholder", "\u{2014}" }
+                                                }
                                             }
                                             tr {
                                                 th { "Stratification Required" }
@@ -710,11 +767,29 @@ pub fn CultivarDetail(slug: String) -> Element {
                                             }
                                             tr {
                                                 th { "Light" }
-                                                td { class: if light == "\u{2014}" { "placeholder" } else { "" }, "{light}" }
+                                                if light != "\u{2014}" {
+                                                    td { "{light}" }
+                                                } else if let Some(ref fb) = sp_light_fb {
+                                                    td {
+                                                        span { class: "estimated-value", "{fb}" }
+                                                        span { class: "estimated-tag", "~ species" }
+                                                    }
+                                                } else {
+                                                    td { class: "placeholder", "\u{2014}" }
+                                                }
                                             }
                                             tr {
                                                 th { "Frost Tolerance" }
-                                                td { class: if frost_tol == "\u{2014}" { "placeholder" } else { "" }, "{frost_tol}" }
+                                                if frost_tol != "\u{2014}" {
+                                                    td { "{frost_tol}" }
+                                                } else if let Some(ref fb) = sp_frost_fb {
+                                                    td {
+                                                        span { class: "estimated-value", "{fb}" }
+                                                        span { class: "estimated-tag", "~ species" }
+                                                    }
+                                                } else {
+                                                    td { class: "placeholder", "\u{2014}" }
+                                                }
                                             }
                                             tr {
                                                 th { "Min Light Hours/Day" }
@@ -724,6 +799,24 @@ pub fn CultivarDetail(slug: String) -> Element {
                                                 th { "Optimal Light Hours/Day" }
                                                 td { class: if opt_light_h == "\u{2014}" { "placeholder" } else { "" }, "{opt_light_h}" }
                                             }
+                                            if let Some(ref fb) = sp_drought_fb {
+                                                tr {
+                                                    th { "Drought Tolerance" }
+                                                    td {
+                                                        span { class: "estimated-value", "{fb}" }
+                                                        span { class: "estimated-tag", "~ species" }
+                                                    }
+                                                }
+                                            }
+                                            if let Some(ref fb) = sp_usda_fb {
+                                                tr {
+                                                    th { "USDA Hardiness Zone" }
+                                                    td {
+                                                        span { class: "estimated-value", "{fb}" }
+                                                        span { class: "estimated-tag", "~ species" }
+                                                    }
+                                                }
+                                            }
                                         }
                                     }
                                 }
@@ -810,6 +903,14 @@ pub fn CultivarDetail(slug: String) -> Element {
                                 }
                             }
                         }
+
+                        if has_any_fallback {
+                            p { class: "species-fallback-note",
+                                "Values marked "
+                                span { class: "estimated-tag", "~ species" }
+                                " are estimated from species-level data."
+                            }
+                        }
                     }
                 },
             }