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Lactuca sativa var. capitata
Growing calendar
Typical timing for central Japan (Kanto region). Shift it for your own climate, and record your actual dates.
Guides
- How to Grow Lettuce from Seed: Light, Soil Warmth and Summer Sowing
- Types of Lettuce: Crisphead, Butterhead, Romaine and Loose Leaf
- Why Lettuce Does Not Form a Head, and Why It Turns Bitter
- Lettuce Diseases and Pests: Keeping the Crown Dry
- When to Pick Lettuce and How to Cut and Come Again
- Lettuce Growing Calendar: Spring and Autumn Sowings
Common problems
Start from what you can see on the plant.
Pests and diseases (44)
Problems recorded for this plant, most serious first.
Sclerotinia Rot
MajorDisease
The crown, stem or head rots in a water-soaked way and is covered in white cottony mycelium. Black sclerotia later form inside and on the surface, and the plant wilts and dies.
Aphids
CommonPest
Small green or black insects cluster on shoot tips and leaf undersides, crinkling the leaves and stopping growth. The honeydew they excrete supports sooty mold that blackens the foliage.
Slugs
CommonPest
Irregular holes are chewed in leaves and fruit with glistening slime trails nearby. By day they hide under pots and bricks or in dead leaves at the base of the plant.
Bacterial Soft Rot
CommonDisease
The crown or the head becomes water-soaked and soft, then collapses into a slimy mush. The rotting tissue gives off a distinctive foul odor.
Downy Mildew
CommonDisease
Pale yellow to yellow-brown angular lesions form on the upper leaf surface with a gray-purple mold in the matching spot underneath. Lesions merge, the leaves die back and the plant declines early.
Tomato Spotted Wilt
OccasionalDisease
Brown necrotic spots and ring patterns appear on the leaves and the growing tips shrivel and darken. Fruit develops concentric yellow rings that make it unmarketable.
Pillbugs
OccasionalPest
Cotyledons and the stem base of young seedlings are gnawed and the seedlings disappear. Fruit resting on the ground gets shallow feeding scars on the surface.
Etiolation
OccasionalDisorder
Internodes stretch long, stems are thin and leaf color is pale. The plant topples easily and becomes vulnerable to pests and disease.
Cutworms
OccasionalPest
Typically a newly transplanted seedling is severed at soil level and found toppled the next morning. Scratch the soil beside the cut seedling and a gray-brown caterpillar turns up.
Fertilizer Burn
OccasionalDisorder
Leaf margins scorch brown soon after fertilizing and the whole plant wilts. Root tips turn brown and growth stops abruptly.
Fusarium Yellows
Disease
Yellowing starts on the lower leaves, the petioles twist and the plant leans to one side. Vascular tissue browns, growth stops, and heading vegetables may die without ever forming a head.
Powdery Mildew
Disease
White patches appear scattered on the upper leaf surface at first, then the whole leaf is coated in a white powder. Leaves later yellow, brown and die back, and reduced photosynthesis cuts growth and yield.
Late Blight
Disease
Dark green water-soaked lesions appear on the leaves and expand quickly into brown dead tissue. White mold forms on the underside and at the lesion edge, and dark brown lesions spread to stems and fruit.
Brown Leaf Spot
Disease
Small light brown to gray-brown spots form on the leaves and enlarge into irregular lesions. When they merge the whole leaf dies and plant vigor drops sharply.
Cucumber Mosaic Virus
Disease
New leaves show a yellow-green mosaic, crinkle, and the whole plant becomes stunted. Fruit colors unevenly and grows misshapen.
Rust
Disease
Small raised orange-yellow to red-brown pustules form on both leaf surfaces, then rupture and release powdery spores. Heavy infection yellows the leaves and kills them early.
Southern Blight
Disease
The stem rots at soil level and white silky mycelium spreads over the crown and the surrounding soil surface. Brown sclerotia the size of rapeseed then form and the plant wilts and dies rapidly.
Potato Leafroll
Disease
Lower leaves roll inward into tubes and become stiff and leathery. The plant is stunted and yellowed, and tubers are small and few.
Root-lesion Nematode
Pest
Elongated blackish brown necrotic lesions form on the root surface and fine roots rot away. Above ground the stand is uneven and plants stay small with pale foliage.
Root Rot
Disease
Fine roots rot brown to blackish brown, growth stops and the lower leaves yellow. The plant wilts easily in the daytime and eventually dies outright.
Root-knot Nematode
Pest
The plant wilts in the daytime and does not recover with feeding or watering. Pull it up and the roots carry beaded chains of galls of varying size with few fine roots.
Gray Mold
Disease
Water-soaked brown lesions form on flowers, fruit and leaves, densely covered by a fuzzy gray mold. Fruit rots and drops, and decay continues in storage after harvest.
Bacterial Spot
Disease
Small water-soaked spots appear on the leaves, later turning brown with yellowing around them. Fruit develops water-soaked or scabby spots from which rot spreads.
Leaf Spot
Disease
Small round brown to gray-white lesions appear on the lower leaves, the centers turning gray with tiny black specks. As they multiply the leaf yellows and drops early.
