Cucumbers yellow leaves - Ask Extension
My cucumbers have good sun, climb a trellis, get fish emullson 5-1-1 fertilizers every 2 or 3 weeks.
Yet not doing so good...yellow leaves show up, c...
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Cucumbers yellow leaves #942114
Asked August 11, 2026, 8:54 AM EDT
My cucumbers have good sun, climb a trellis, get fish emullson 5-1-1 fertilizers every 2 or 3 weeks.
Yet not doing so good...yellow leaves show up, cucumbers are yellowish/light green.
Montgomery County Maryland
Expert Response
Here is the info from the UnMD, and specifically look at the second link discussing Common Problems
Growing Cucumbers in a Home Garden | University of Maryland Extension
Key to Common Problems of Cucumbers | University of Maryland Extension
After you look at Common Problems photos, to rule out those issues, consider the possibility of a watering problem due to our weather. Cucumbers want consistently moist soil, but they don't like staying saturated. Excess water can cause chlorosis (yellowing), and Maryland Extension specifically cautions against assuming yellow leaves mean they need more fertilizer.
Or, you may have a nutrient/micronutrient deficiency:
- Nitrogen / Potassium: Older lower leaves turn uniformly pale green, then yellow, starting from the edges and working inward.
- Magnesium / Iron: Leaves display "interveinal chlorosis"—the leaf tissue between the veins turns pale yellow while the main leaf veins stay vibrant green.
- Fruit effect: Cucumbers turn pale yellow-green, taper at the stem/blossom ends, or taste bitter.
- Quick Action Plan
- Switch fertilizing: Pause the 5-1-1 fish emulsion and apply an organic flower & fruit fertilizer rich in potassium and micronutrients (iron/magnesium).
- Harvest current yellow fruit: Remove yellow cucumbers immediately so the plant stops dumping energy into over-ripe seed production.
Finally, cucumbers have a relatively short season. Maybe they are just too old now to be productive.
Good Luck
Len
