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Spinach Growing Problems: Troubleshooting

Spinach plant1
Spinach plant grow in cool season
Spinach growing problems are often related to growing spinach in the wrong season.

Spinach growing problems are often related to growing spinach in the wrong season.

Grow spinach in cool weather. Sow spinach in the garden as early as the ground can be worked in spring. Make succession sowings every 10 days for a continuous harvest of young tasty leaves. Continue sowing spinach until just a few weeks before the start of summer.

Sow spinach again in late summer for a cool fall harvest. In mild winter regions, sow spinach in autumn for spring harvest.

For spinach growing tips see Spinach Growing Success Tips at the bottom of this post.

Common spinach growing problems with cures and controls:

• Seedlings fail to emerge; poor germination. Seed sown too shallow. High temperatures or dry conditions will cause seed to dry and fail to germinate. Sow seed in cool weather. Keep soil evenly moist to allow for germination.

• Plants are eaten or cut off near soil level. Cutworms are gray grubs ½- to ¾-inch long that can be found curled under the soil. They chew stems, roots, and leaves. Place a 3-inch paper collar around the stem of the plant. Keep the garden free of weeds; sprinkle wood ash around base of plants.

• Seeds rot or seedlings collapse with dark water-soaked stems as soon as they appear. Damping off is a fungus that lives in the soil, particularly where humidity is high. Do not plant in cold, moist soil. Make sure soil is well drained.

• Leaves are faded yellow. Nitrogen deficiency. Spinach is sensitive to inadequate nitrogen. Side dress with compost tea every 10 to 15 days. Add aged compost to planting beds twice each year.

• Plant bolts–flowers and sets seed–before leaves are ready for harvest. Bolting can be brought on by long daylight and very warm temperatures or cool temperatures followed abruptly by very warm temperatures, 80°F or greater. Plant spinach so that it comes to harvest in cool weather. Plant varieties that resist flowering–bolting: Bloomsdale Long Standing, Big Crop, America. Plant spinach in late summer so that plants mature in the cool days of fall.

• Leaves curl under, deformed, and yellowish; small shiny specks on leaves. Aphids are tiny, oval, and yellowish to greenish pear-shaped insects that colonize on the undersides of leaves. They leave behind sticky excrement called honeydew which can turn into a black sooty mold. Remove aphids from leaves with a blast of water from the hose. Use insecticidal soap.

• White thread like tunnels within leaves. Leafminer larvae tunnel inside leaves. Destroy infected leaves and cultivate the garden to destroy larvae and keep adult flies–they are black with yellow stripes–from laying eggs. Cover crops with floating row covers.

• Tiny shot-holes in leaves of seedlings. Flea beetles are tiny bronze or black beetles a sixteenth of an inch long. They eat small holes in the leaves of seedlings and small transplants. The larvae feed on roots of germinating plants. Spread diatomaceous earth around seedling. Cultivate often to disrupt life cycle. Keep garden clean.

• Irregular small holes eaten in leaves. Cabbage lopper is a light green caterpillar with yellow stripes running down the back; it loops as it walks. Keep garden clean of debris where adult brownish night-flying moth can lay eggs. Cover plants with spun polyester to exclude moths. Pick loppers off by hand. Use Bacillus thuringiensis. Dust with Sevin or rotenone.

• Leaves are chewed. Snails and slugs feed on leaves. Hand pick at night when these pests feed or set out saucers of beer at soil level to attract and drown slugs and snails.

• Leaves and stems are partially defoliated. Armyworms are dark green caterpillars the larvae of a mottled gray moth with a wingspan of 1½ inches. Armyworms mass and eat leaves, stems, and roots of many crops. Armyworms will live inside webs on leaves. Handpick caterpillars and destroy.

• Plant yellows on one side; plant is stunted are stunted. Fusarium wilt or fusarium yellows, also called spinach yellows, is a fungal disease which infects plant vascular tissues. Fungal spores live in the soil and can be carried by cucumber beetles. Plant disease-resistant varieties. Rotate crops. Remove and destroy infected plants.

• Veins in leaves yellow. Spinach blight or spinach yellows is a mycoplasma disease spread by leafhoppers. Remove infected plants. Control leafhopper. Keep the garden free of weeds which can harbor disease.

• Small yellow spots on outer leaves with brown centers enlarge; spot may drop out leaving a ragged hole. Cercospora leaf spot is a fungal disease spread by heavy rainfall and warm temperatures. Keep weeds down in the garden area; they harbor fungal spores. Avoid overhead watering.

• Round water-soaked spots on leaves turn reddish brown to black. Anthracnose is a fungal disease that spreads in high humidity and rainfall. Leaves may wither and fall. Plant may die back. Spray or dust with a fixed copper- or sulfur-based fungicide every 7 to 10 days. Remove and discard infected plants. Avoid working in the garden when it is wet which can result in spread of spores. Keep tools clean.

• Irregular pale green to yellowish to brownish spots on upper leaf surfaces; grayish powder or mold on undersides. Downy mildew is a fungal disease often triggered by wet and humid weather or too frequent overhead irrigation. Improve air circulation. Plant resistant varieties. Rotate crops. Keep garden free of plant debris that can shelter fungus spores.

Spinach Growing Success Tips:

Planting. Spinach is a cool-weather crop that grows best in full sun. Where the weather is very warm, grow spinach in partial shade. Grow spinach in rich, well-drained soil; add aged compost to the planting bed before planting. Spinach will germinate poorly where soil temperatures exceed 75°F. Once seeds germinate and begin to grow, mulch the soil to maintain an even, cool soil temperature.

Planting time. Sow spinach in spring as early as 8 weeks before the average last frost date. For best flavor, spinach should come to harvest before day time temperatures exceed 70°F; increased day length also will cause spinach to flower and set seed. • For a fall crop, sow spinach in late summer 8 weeks before the first expected frost. • For an early spring harvest, sow spinach in fall about 6 weeks before the first expected frost and then protect plants from freezing in winter (plants will grow before the first freezing temperatures then stop and go nearly dormant through the winter). When spring arrives, these plants will complete their growth and be ready for harvest. In mild winter regions, sow spinach every 2 to 3 weeks throughout the fall.

Care. Keep spinach evenly moist and mulch planting beds to keep the soil cool. Protect seedlings from flea beetles, aphids, and leafhoppers with floating row covers. Thin plants to 6 inches apart for best growth and to maintain good air circulation. Keep the garden free of plant debris that can harbor pests.

Harvest. Begin picking spinach leaves when the plant has formed 6 to 8 leaves; harvest the whole plant when leaves are 4 to 6 inches long.

More tips at How to Grow Spinach.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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  1. My plants were fine as I managed to harvest twice already however I noticed recently that my spinach leaves are being eaten to the stem where only the stems remain with no green foliage.No sign of bugs nor worms. Please help……….

    • You likely have night visitors such as snails, slugs, or earwigs. You can sprinkle diatomaceous earth around the plants as a barrier. If you suspect birds or squirrels are eating the plants, cover them with a floating row cover. Ask for these items at a garden center.

  2. A fAew years ago I showed spinach on my allotment. Now every year new spinach plants grow nearby. I have some really nice looking spinach this year but is it safe to eat? I think the plants from last year have set their own seed.

    • If the spinach reseeded, and you are sure it is spinach, then it should be safe to eat. Nature sowed the seeds saving you some time and effort.

  3. Thank you, Steve, for your prompt reply. There is nothing that looks like a bug. I am pretty sure these “hairs” are filaments grown from the spinach plant itself. There does not seem to be a way of attaching a photo to this message, otherwise I could show you what they look like.

    • There is a disease called “spinach white rust”; it looks a bit like downy mildew which can look a bit like white filaments. The disease looks like downy mildew to start, then the leaves become chlorotic and then they develop small blisters. This disease usually happens in cool weather. It can be treated with a fungicide.

  4. My Bloomsdale Long Standing spinach is starting to bolt. (We’ve had a lot of hot weather lately.) At the juncture of each leaf with the stem, there is a whitish hairy growth — like hair under an armpit — a ball of straight spikes of “hair” growing out in all directions, each spike about 1/8 of an inch or so in length. The spinach leaves are not yet bitter tasting, so I would like to eat the spinach, but I wonder if these hairy growths are edible. Are they just another manifestation of bolting (besides the early flower buds), or are these something else?

    • The white filaments could be mold–which is possible if the weather has been humid or wet–or they could be mealy bugs. You can crush mealybugs with your fingers or spray them neem oil. Given that the plants are bolting, you should harvest. You can harvest the leaves and leave the white mold or bugs behind.

    • New Zealand spinach is a vining plant; true spinach is not a vine. If you are growing true spinach, it is likely the plant is stressed.

  5. A couple of days ago my spinach was growing well and had bountifully of baby spinach leaves, approx 4-6 on each plant.
    However I went to them this morning and they all look ‘sad’. As in a most wilted and not standing high anymore, almost resting on each other?

    • Be sure the soil is just moist, but not wet, and do not let the soil dry out. The roots are still shallow and must have moisture. Also protect the seedlings from cold nights.

  6. In 2018, I dedicated a 6 x 6 raised bed to Bloomsdale Long-Standing and scattered seed. Germination was good and bed was thinned appropriately. Plants slowly grew a few true leaves and then stopped growing. I left them alone and sometime in the season, one plant grew beautifully and I harvested spinach from it well into the summer. The others just sat there. I have the same problem with transplants that I purchase. They just don’t grow but otherwise look fine. I have since tried other varieties of spinach with the same result. I have rich soil with compost. I’m In Coos Bay on the Oregon coast at about elevation 50. I’m just really curious as to why one plant did well out of many. None of the plants looked unhealthy. I have long, cool summers so this seems like crop that should thrive.

    • If both seeds and transplants have done poorly in the same bed, the likely problem is either sunlight or soil, or both. Near the coast, spinach can be planted in full sun. If the soil has not been changed in the last year, it may be time to replace the soil. Replace in full or add commercial organic planting mix to the bed; that should eliminate any soilborne organisms that may be affecting the plants. Do not fertilize apart from add B1 or another starter fertilizer.

    • As soon as spinach is cut from the plant, the living cells immediately begin to decline and soon decay. The decay is dark colored. Use spinach quickly after harvest or refrigerate it.

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