Spinach is a hardy green leafy plant that requires very little maintenance. They love the cold, so this is a great crop to grow in early spring and fall. In some areas, it’s even possible to continue growing your spinach right through the winter.
There are some common problems that you can face when growing spinach, including spinach leaves turning yellow/brown or brown/white spots.
We’re going to discuss common reasons for leaf discoloration, including:
- Poor growing conditions
Once you’re finished with this article, you’ll be ready to become a spinach growing champion, with bright leafy greens worthy of any horticultural society newsletter. Or at least as a new addition to your Insta story or garden blog. The point is, you’ll want to share your success!
Spinach Leaves Turning Yellow
Spinach leaves that are starting to turn yellow can have multiple causes, including malnutrition, diseases, pests, or improper growing conditions.
Depending on the cause of the discoloration, you can reverse the damage using simple remedies. But in some cases, you might have to destroy your crops and start over. Let’s look at some common problems for yellowing leaves.
Your soil needs balanced nutrition to grow healthy green spinach. Use a home testing kit like Luster Leaf 1601 Rapitest to check the nutritional levels of the dirt. Not only does this test check the pH levels, but also other crucial components like nitrogen and phosphorus.
Spinach needs a pH level of 6.2-6.8, making it more acidic. Your plants will protest by turning yellow if your soil has too much alkaline, which causes a number higher than seven.
You also need the proper combination of nitrogen, potassium, and phosphorus in your soil to prevent yellowing leaves. Nitrogen deficiency is a common cause of yellowing leaves. A lack of boron can also be the culprit.
Compost is a natural way to balance the soil pH levels. But if you need to add more acid to your soil to bring the pH below 7, you can use lime, like Bonide Chemical Hydrated Lime. If your soil has too much alkaline, you can use coffee grounds.
Spinach can contract multiple diseases, which can turn the leaves yellow. With many of these conditions, the damage is irreversible and requires you to destroy your infected plants, so the disease doesn’t spread.
Mosaic virus, also called blight, is a condition that starts with yellow leaves. As the disease progresses, the leaves become thin, curl inward, and have wrinkled distorted growth.
This disease is transferred between plants by insects like leafhoppers, aphids, and cucumber beetles. There is no treatment for spinach that gets this disease, so once you diagnose it, you should destroy any infected plants to prevent further spreading.
Prevention is the best way to ensure your plants don’t end up with mosaic. Treat your plants with a safe vegetable insecticide such as Safer Brand Insect Killing Soap, which prevents insects like leafhoppers, aphids, and harlequin bugs.
Beet Curly top
With Beet Curlytop disease, you’ll notice your spinach leaves starting to turn light green and then yellow, beginning with the younger leaves first.
The leaves will also become curled and deformed with mottled patches of discoloration. The leaf veins become purpled while the texture becomes thick and stiff. You’ll even notice bending around the petioles.
Leafhoppers transmit Curly Top during warm conditions. There is no cure, so you should destroy the infected crops, so the disease doesn’t spread to your healthy plants. Preventative measures such as keeping your garden clear of weeds and pests reduce the chances of your spinach contracting Curly top.
If you’re noticing stunted, yellow plants with weak growth around the lower leaves that are suddenly starting to wilt, you might be dealing with a case of root rot, also known as damping off.
In addition to wilted yellow leaves, you might also notice discolored water-logged roots with necrotic lesions. Older plants may suddenly fall over and die. Seeds may not germinate properly and die as tiny seedlings.
This condition is caused by fungi that come from too much water. Many people get root rot confused with overwatering, as they share similar symptoms. To prevent root rot, avoid giving your spinach plants too much water and ensure you have proper drainage if you live in an area that experiences a lot of rain.
You can also use a safe vegetable fungicide like Organic Laboratories Organocide to treat root rot and to prevent future occurrences. And be sure to use crop rotation and don’t plant spinach crops in the same location back to back.
Aster Yellows is a disease that affects multiple types of plants, including spinach. As the name implies, spinach that has Aster Yellows will have yellow leaves.
Your plants will also experience stunted growth, secondary shoots, and small, narrow curled leaves that start to lose color, with signs of chlorosis – yellow leaves with green veins. Over time, the color can change to red or purple.
This condition is transferred by leafhoppers, which feed on your spinach plants by sucking the nutrients out. Unfortunately, there is no treatment for Aster Yellows, so you’ll want to consider using preventative measures, such as insecticide, to discourage leafhopper infestation in your garden.
Also, keep your garden free of weeds and promptly dispose of infected plants to prevent the spread of the disease to your healthy crops.
Spinach Seedlings Yellow
Seedlings are the young plants that grow out of the seeds. When your spinach starts to emerge from the ground, it begins with two small leaves called cotyledons. As your plants mature, these beginner leaves will turn yellow and die. You shouldn’t be alarmed.
But if your seedlings are starting to yellow and the cotyledons have already dropped, you could be looking at other problems. Failure to address these issues could result in seedlings that don’t grow into healthy plants or die altogether.
Lack of Light
One of the most common problems that cause seedlings to turn yellow is not enough light. Spinach seedlings need 12 hours a day of direct light and temperatures between 35℉ and 75℉ (1.667℃ to 23.8889℃).
If your plants are outdoors, you should make sure you haven’t planted in a shady spot that isn’t getting enough sun exposure. For indoor plants, supplement window time with an artificial light source.
Another issue could be improper watering. A lack of enough water can cause yellowing seedling leaves. If your soil feels dry and brittle when you poke your finger into the ground, your plants aren’t getting enough hydration. Increase the amount of watering you’re doing as younger plants need a lot of water to grow.
However, be careful not to overwater your plants. The soil around your seedlings should feel spongy and damp but not soaked with water pooling on top. Your seedlings could be turning yellow due to too much hydration to the point that they are drowning.
Most of the time, seedlings won’t need fertilizer when they first start growing. Using a fertilizer too early can cause your plants to suffocate from fertilizer buildup, which can turn seedling leaves yellow.
A tell-tale sign of too much fertilization will be white deposits on the leaves or at the bottom of the container if you’re growing them indoors. Stop applying fertilizer immediately and flush your plants with water. You might even have to transplant them to new soil if too much fertilization has occurred.
But if you haven’t used any fertilizer on your plants and you’re noticing yellow seedlings, you might be dealing with a nutritional deficiency caused by malnutrition. Try adding a bit of fertilizer to your plants to see if the yellowing leaves improve.
Spinach Leaves Turning Brown
Brown spinach leaves can be caused by numerous problems, including disease, pests, malnutrition, and temperature.
Downy mildew is a disease that causes yellow patches to appear on the leaf. On the bottom side of the leaves, you may notice purplish-gray spores. As the disease progresses, the yellow spots turn brown.
There is no treatment for downy mildew, but using a vegetable safe fungicide can help with prevention, so there’s less chance that your plants will develop downy mildew. You should destroy any infected plants and rotate crops every three years.
Downy mold grows in wet, cold conditions, so it’s essential to keep the spinach leaves as dry as possible. Use a drip irrigation system instead of watering your plants overhead. And if using row covers, wait until your plants are completely dry before replacing the covers.
Anthracnose is a disease caused by a fungus called Colletotrichum spp. With this condition, your spinach leaves will turn thin and papery, with small water-spots that turn brown or tan as they get bigger.
In advanced stages, these spots will combine to form large lesions. You may end up with severe blighting as well. This disease passes between plants through water, so you must avoid water splashing between plants, such as overhead sprinklers.
There is no treatment for anthracnose, but you can reduce the chances by keeping your crops properly fertilized, avoiding overhead watering, and planting resistant-free, heat-treated seeds. You can also use a copper fungicide like Bonide 811.
Cercospora Leaf Spot
Cercospora Leaf Spot is a disease that’s caused by the Cercospora beticola fungus. It starts with small brown or off-white spots with a red border on the outer leaves. These spots turn into lesions and become gray as the disease progresses.
You might also see stomata, which are small black dots that look like dirt specks. Over time, the lesions spread to the rest of the plant, destroying most of your leaves. This fungus is spread by wind, insects, contaminated gardening tools, or water splashing between plants from irrigation or rain.
You can prevent this condition by doing crop rotation, planting disease-free seeds or seeds treated with hot water (soak seeds in 122 water for 15 minutes), using proper spacing between plants, and not using overhead irrigation or allowing plants to stay wet overnight. You can also use fungicides as a preventive treatment measure.
Insect like spider mites can cause spinach leaves to turn brown and dry out, taking on a scorched appearance under direct light.
Examine the underside of your spinach leaves for infestation. Using an insecticide that contains spinosad can prevent spider mite infestation.
Watering is a critical component of growing healthy spinach. Both too much and too little water can cause your leaves to turn brown. Spinach needs 1” to 1.5” (2.54 cm to 3.81 cm) of water a week, either by rain or hose.
Adding too much water can make the roots suffocate, and the leaves turn brown. But not giving your plants an adequate amount of water can also make them wilt and turn brown. Dehydration reduces the plant’s ability to use photosynthesis, which is how they produce food.
When low water is the problem, you’ll see an immediate improvement of your plants within hours of being watered. The leaves will perk up and slowly start to regain color. Mulch helps maintain proper moisture and temperature for your spinach.
Overfertilization is a severe but treatable problem that can frequently turn spinach leaves brown and cause them to be dried out and brittle.
Too much fertilizer is bad for both the leaves and the plant roots. Most fertilizers contain high levels of salt, which can stop your plants from absorbing water and nutrients.
Spinach Leaves Have Brown Spots
If you’re noticing small, light brown spots on the stems of your spinach, you might be dealing with a problem of Blackleg, which is caused by the fungus Leptosphaeria maculans. These spots become sunken and can make the stems rot. Fungicides help prevent Blackleg. Destroy any crops that continue to show infection.
Another condition that can cause brown spots is white spot (yeah, somewhat ironic) disease. This disease is caused by the fungus Pseudocercosporella capsellae and causes brown or white spots on the leaves before they start to turn yellow and fall off.
Wirestem causes reddish-brown cankers on the stem of your spinach. As the disease progresses, the stem starts to rot and peel. Use proper watering, fumigation, and treated seeds to prevent this condition.
Anthracnose causes tan or brown lesions on the underside of spinach leaves. These dots will be around the size of a pinhead. Prevent anthracnose by keeping your garden free of weeds, twigs, sticks, and pests.
Spinach Leaves Have White Spots
If you’re noticing that your leaves are turning white or have white spots, it’s most likely a fungal disease. Sadly, most of these can’t be treated, but you can take preventative measures to reduce the chances of your spinach plant turning white.
White rust is a condition that causes small white blisters on spinach, starting with the bottom first. Or you could be dealing with Cercospora, which creates tiny white spots that have dark halos around them.
Downy mildew is another condition that can make white spots appear on your spinach leaves. As the condition worsens, the foliage will appear more white than green from all the gray-white or brown fuzzy patches, which appear on the bottom of the leaves. The top of the leaves has corresponding yellow spots.
Spinach Plant Frost
Spinach is a cold-tolerant plant that can grow in early spring, fall, and even some warm winters, and in temperatures as low as 15℉ (-9℃). In terms of frost, spinach can survive, but if you’re expecting a hard freeze, use a cold frame or a thick layer of mulch to provide extra heat, so your plants don’t get frostbite.
Young plants should always be covered if frost is in the forecast, as these plants aren’t ready to withstand the dramatic drop in temperature. Keeping them covered at night is a great way to protect them.
Spinach Plant Bugs
If your spinach leaves are starting to present with white tunnels growing on the leaves, the most common cause is an infestation of leaf miners. Leaf miners are small bugs that burrow holes into the leaves. You can use an insecticide that includes spinosad to prevent infestation.
Aphids are another common pest that can infect spinach. This insect drains the sap out of your plants, causing the leaves to cup and curl. Your plants might also suffer from stunted growth. Aphids can transfer diseases such as mosaic and sooty mold, so you want to keep your garden pest-free. You can use a pesticide to prevent aphid infestation.
Spinach crown mite is a tiny, transparent insect that lives in the crown of seedlings and older plants. These pests leave small holes in the leaves, which can make them deformed—mites like cold, wet weather, which is optimal growing conditions for plants like spinach. Use an insecticide and keep your garden clear of plant debris and weeds.
Spinach is a great crop for those just beginning to grow their own plants. These plants don’t require much maintenance, other than proper watering, and ensuring the plants stay disease, clutter, and pest free. You can use fungicide, insecticide, and mulch to keep your plants healthy and ready for harvest.