Radish Plant Has Yellow Leaves: Why Do Radish Leaves Turn Yellow

Radish Plant Has Yellow Leaves: Why Do Radish Leaves Turn Yellow

Radishes are vegetables grown for their edible underground root. The portion of the plant above ground is not to be forgotten, however. This part of the radish produces food for its growth and also stores additional nutrients needed down the growth phase. So it comes as no surprise that yellow radish leaves are a sign that there is a radish growing problem. Why do radish leaves turn yellow and how can you treat a radish plant that has yellow leaves? Read on.

Why Do Radish Leaves Turn Yellow?

Radish growing problems may stem from anything from overcrowding, lack of adequate sun, competing weeds, insufficient water, nutrient deficiency, pest and/or disease. Radish leaves that are turning yellow may be the result of any number of the above as well.

There are a number of diseases that result in yellowing leaves as at least one sign of infection. This may include Septoria leaf spot, which is a fungal disease. Diseased foliage appears as yellow spots on radish leaves that look almost like water blotches with gray centers. Avoid Septoria leaf spot by amending with organic matter and planting in a well-draining area of the garden. Also, practice crop rotation. To curb the disease when plants are already afflicted, remove and destroy infected leaves and plants and keep the garden free of debris.

Another fungal disease is Blackleg. This infection presents as radish leaves turning yellow between the veins. The leaf margins brown and curl up while the stem becomes a dark brown to black and slimy. The roots also become slimy and brown-black towards the stem end. Again, prior to planting, amend the soil with plenty of organic matter and ensure that the site is well-draining and practice crop rotation.

If your radish plants become wilted and appear weak with yellow leaves combined with oval, red blotches at the stem base and roots with red streaks, you probably have a case of Rhizoctonia or Fusarium root (stem rot). This fungal disease thrives in warm soil. Rotate crops and plant disease free plants. Remove any infected plants and debris. Solarize the soil in the late spring or summer to kill off any overwintering spores.

Club root is another fungal disease (Plasmodiophora brassicae) that not only cause leaves to yellow, but swells roots with tumor-like galls. This disease is common in wet soils with a low pH. The microorganism can live in the soil for 18 years or more after an infected crop! It spreads via soil, water and wind movement. Practice long-term crop rotation and remove and destroy any crop detritus and weeds.

Common in cool weather, downy mildew causes angular yellow spots on leaves that eventually become tan colored, papery textured areas surrounded by a yellow border. Fuzzy gray to white mold grows on the underside of the leaves and brown to black sunken areas appear on the root with a rough, cracked exterior.

Black rot is yet another radish disease that results in yellowing leaves. In this case, the yellow areas are distinct V-shaped lesions on the margins of the leaves with the point of the “V” following a vein towards the base of the leaf. The leaves wilt, yellow and soon brown and die as the disease progresses. The veins become black throughout the entire plant from leaves, stems and petioles. Hot, humid conditions foster black rot, which may be confused with Fusarium Yellows. Unlike Fusarium, ailing foliage in black rot coincides with bacterial slime.

Additional Reasons a Radish Plant Has Yellow Leaves

Yellow leaves on radish plants may also be due to insect infestation. A virus called Aster Yellows is a mycoplasma disease spread by leafhoppers, which act as a vector. To combat Aster Yellows, control the leafhopper population. Remove infected plants and keep the garden weed free since weeds harbor the disease by sheltering the leafhoppers.

Brilliantly marked Harlequin bugs suck fluids from plant tissues, resulting in wilting plants with deformed leaves dotted with whitish or yellow spots. Handpick these insects and destroy their egg masses. Keep the garden free from weeds and plant detritus that will shelter the bugs and their eggs.

Lastly, yellowing of radish leaves may also be the result of a nitrogen deficiency. This is fairly rare since radishes aren’t heavy feeders but, if necessary, feeding the plant with a fertilizer high in nitrogen will return the plant to its brilliant green.

Start your radishes properly and you may be able to avoid many of these radish problems. Sow in a spot of at least six hours of sun per day. Prepare the area by raking free of weeds and debris. Work in ample compost or aged manure and rake the area smooth. Then sow seeds in furrows about an inch (2.5 cm.) apart and ½ inch (12.7 mm.) deep with seeds spaced ½ to 1 inch (1.3 to 2.5 cm.) apart.

Cover lightly with soil and water in until moist. Keep the bed moist, not drenched, consistently. Thin the radishes, leaving 2-3 inches (5-7.5 cm.) between plants. Keep the bed free of weeds. Pick an occasional radish or two as they grow to check for any insects below the surface. Discard any infected plants immediately.

Seedling Problem No. 1

Seeds don't come up

Cause: About 90 percent of fresh seeds should sprout, but after six months or more in storage, germination rates can begin to decline. If you get low germination with fresh seeds, your soil mix may have dried out before the tiny sprout could take up enough moisture to start growing.

Solution: Before you plant, soak your seeds in water for 30 minutes so the seed coats start to soften and they begin absorbing moisture. Dampen the soil mix thoroughly, and then sow the seeds. After planting, be sure the mix stays consistently moist. Even a few dry hours can stall the sprouts' growth.

Top 10 Questions About Radish Plants

Radishes are one of the easier vegetables to grow, but even easy-to-grow veggies can be fraught with problems. Here at Gardening Know How we get lots of questions about radishes, and our goal is to provide answers to those inquiries to the best of our knowledge. The following information includes the 10 most commonly asked questions about radish plants in the garden.

For good root development, I like to till or spade my radish patch to a depth of 8 to 12 inches (20 to 30 cm.). The finer the soil, the better. I remove all small rocks or sticks, as these can cause deformed radishes. Then I prefer to use a hand-held seed planter to sow the seed. It makes it easier to plant the seeds a consistent ½ inch (12 mm.) deep and space them 1 inch (2.5 cm.) apart. I find planting a short row every week creates a steady supply of radishes at harvest time.

I define the boundaries of my radish patch with inexpensive 12-inch (30 cm.) sections of plastic fence to make it easier to find my seedlings once they sprout. Even a short piece of fence deters pests, like rabbits, from grazing on my plants. Securing netting over the fence is added security. As for invertebrate pests, I plant in early spring before the radish eating bugs are active. Later in the season, row covers, insecticidal soap, neem oil or predatory insects can discourage bugs.

You could compost the radish leaves or feed them to chickens, but if you’re looking for a new culinary adventure, try eating them. Like the root, radish tops have a peppery flavor. Young leaves can be eaten raw in salads or steamed like other green, leafy vegetable. Young radish greens can also be used to make pesto, quiche or smoothies. Avoid older leaves, as they tend to develop a coarse texture as they age. Some varieties also have hairy leaves, even when young. When growing radishes for the greens, try Daikon, a popular variety found in microgreen mixes.

Flowering radishes have bolted. When this happens, the bulb stops growing and becomes woody in texture. To prevent bolting, plant radishes in early spring or late fall, as warm temperatures and long daylight hours are the culprit. Dry conditions can also encourage radish plants to go into reproductive mode. Water regularly when rainfall is less than an inch (2.5 cm.) per week. Mulching can also keep soil temperatures cooler and delay the onset of bolting.

Radish leaves can turn yellow for any number of reasons, but one of the most common is a lack of water. Radishes require 1 inch (2.5 cm.) of water per week. Supplying additional water when rain levels fall below this amount. If you’re positive the radishes are receiving sufficient water, next consider whether their growing requirements are being met. Do they have adequate light, nutrients and room to grow? If so, then I’d suspect one of several diseases which can plague radishes and cause the leaves to turn yellow. These include septoria, blackleg, fusarium, club root, black rot and aster yellows.

To prevent radishes from getting too hot, it’s essential to harvest them as soon as they reach maturity. I like to use the maturity date information found on the seed packet as a guideline. As that date approaches, it’s best to frequently check the radish patch since weather conditions can alter growth rates. Either pull out a radish plant or gently brush the loose soil away from the crown of the radish plant to judge the size of the root bulb. Most varieties of radishes are harvested when the root is about 1 inch (2.5 cm.) across.

I’ve frequently dealt with this problem and for different reasons. Root vegetables require loose, fine soil to develop. I like to incorporate organic compost into the soil, then till or hand spade the area to a depth of 8 to 12 (20 to 30 cm.). The finer the soil breaks up, the easier it is for the radishes to grow bulbous roots. Overcrowding is another cause for string-like radish roots. Due to their small size, sowing radish seeds by hand makes it difficult to achieve 2-inch (5 cm.) spacing between plants. Using a hand held seeder or thinning seedlings helps. Finally, feed with a balanced fertilizer (10-10-10), as too much nitrogen discourages root development in radishes.

To prolong the shelf life of fresh radishes, start by removing the tops or greens. Wash and dry the radishes before placing them in a zipper-seal plastic bag. Place a damp paper towel in the bag to provide moisture and prevent the radishes from becoming soft and wilted. Remove as much air as possible before sealing the bag. Store the bag of radishes in a cool, dark place. The crisper drawer in the refrigerator is a good choice. Radishes can also be blanched and frozen for future use in cooked recipes.

As with beets, soil conditions are the likely cause of poorly formed radish bulbs. In general, root vegetables develop best in a loose, organic soil with a fine texture. Due to the size of a mature radish root, even a small stick or rock can block the root’s ability to expand properly and cause deformity. I like to add compost and organic matter, like shredded leaves, to my garden in the fall to allow time for decomposition. I till in the spring to break up the soil, then choose a spot with the finest particle size for planting my radishes. I also water lightly to keep the soil slightly moist and prevent surface crusting.

This is a common problem most gardeners, including myself, have experienced. Spicy radishes result from poor growing conditions and delayed harvest. Ideally, radishes should grow quickly and be ready for harvest in approximately 25 to 35 days, depending on the variety. To keep radishes on schedule, plant them in cool weather. Select a sunny location in the garden and keep the soil evenly moist. Use a balanced fertilizer and thin seedlings to give radishes 2 inches (5 cm.) of space. Harvesting as soon as the bulb reaches a mature size will keep them sweet.

We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We’re always here to help.

Underwatering A ZZ Plant Can Lead To Yellowing Leaves

A ZZ plant doesn’t need a lot of water, so it can be easy to forget about watering it all together. Drastic lack of water will lead to leaf color change, shriveling, and dropping. This can be quite distressing to the house plant lover!

If your plant’s soil is very dry, underwatering could be the problem. The good news is that by adjusting your watering schedule, your ZZ plant can bounce back fairly quickly.

What to do if your ZZ plant is turning yellow from underwatering:

  • Slowly start watering the houseplant, but don’t drench the soil. When a plant is suffering from lack of water, it can be tempting to do the exact opposite and start overwatering it. Be sparing with your water.
  • Make sure that you tip excess water out of the drainage saucer. Don’t allow the plant to sit in water.
  • If you want to boost health and nutrition, you can add soluble fertilizer to your water mix. Only mix it to half the dosage strength suggested on the package.

How much water does a radish plant need?

Water your radishes 2 to 3 hours at a time and then wait until the soil has dried to at least a 4 inch depth. If the radish root is pithy and woody the temperature of the soil has likely been too high and the watering spotty.

Also, how long do radishes take to grow? about four weeks

Furthermore, how do you water radish plants?

Radishes need water, but not too much. Radishes will thrive in a seedbed with proper drainage. Keep the soil evenly moist, but not soaked. Don't allow the soil to completely dry out before watering.

What does a radish need to grow?

For the most part radish seed growth is best when they are planted in cool soil early spring or fall are the preferred seasons for many varieties. Planting radishes from seed works best if the soil is moist but does not have standing water healthy plants will resist pests and diseases more readily.


Defoliation is a term that refers to removing fan leaves. Defoliation is used to manage plants and expose flowers to more light. Removing all of the yellow leaves on your plants won't resolve their issues. It's a sign that your plant is experiencing difficulty, so cultivators must address the underlying issues.

That being said, growers can defoliate yellow leaves to a certain extent. Severely wilted leaves are beyond help—defoliate at will. However, cultivators should save leaves that only exhibit early signs of yellowing.


Yellow leaves aren't always a bad sign. Sometimes they can be a natural phenomenon, or intentionally triggered by growers.

The youngest leaves at the bottom of plants close to full maturity will turn yellow and die off—don't worry! Almost all fan leaves will start to become yellow as harvest time approaches. During this period, growers stop feeding their plants in a process known as flushing. Flushing encourages flowers that produce a much smoother smoke. Yellow leaves are a good sign in this context!

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