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How to Fight Blossom End Rot to Save Your Tomato Harvest Full Guide of 2023

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how to fight blossom end rot on tomato plantsYou’ve nurtured your tomato plants from seedlings into lush, fruit-bearing vines. But as you inspect those ripening globes, your heart sinks. Instead of a flawless, bright red skin, you see a rotten, sunken lesion on the blossom end.

Though unsightly, it won’t ruin the entire tomato or spread disease. By understanding the causes and implementing preventive care, you can still harvest bushels of unblemished tomatoes this season.

Blossom end rot results from erratic moisture levels, which prevent proper calcium uptake. While you can’t reverse damage that’s already occurred, you can take steps to avoid future incidents.

With some thoughtful watering practices, mulching, and calcium supplementation, your plants will rally. Soon you’ll be slicing vine-ripened tomatoes with nary a nibble from blossom end rot.

Key Takeaways

  • Water deeply and consistently, about 1 to 2 inches per week. Consistent watering is key to preventing blossom end rot.
  • Apply mulch around plants after fruit sets to help retain soil moisture. Organic mulches like bark or straw work well.
  • Immediately remove and discard any affected fruit. This helps prevent further spread.
  • When possible, select tomato varieties that are resistant to blossom end rot. Look for BER resistant on seed packets.
  • Consider adding calcium supplements if soil is deficient. Products with calcium nitrate or gypsum can help.
  • Avoid over-fertilizing with nitrogen, which can encourage rapid growth and moisture stress.
  • Monitor soil pH and amend if needed. Tomatoes prefer a pH between 6.0-6n5.

What Causes Blossom End Rot?

What Causes Blossom End Rot
Blossom end rot on your tomatoes happens because calcium uptake gets disrupted. Calcium is a vital nutrient that moves from the roots through the plant to growing fruits and leaves. When the soil lacks sufficient moisture, the movement of this essential calcium is hindered.

Hot, dry conditions make the problem worse. Inconsistent irrigation causes fluctuations in calcium delivery, leading to poor calcium absorption by the plant. With inadequate calcium in the developing fruits, dark leathery patches form on the bottom blossom end.

These unsightly marks are blossom end rot, a physiological disorder triggered by lack of calcium.

Focus on maintaining uniform soil moisture to enable a steady supply of calcium. Water deeply and regularly without oversaturating the soil. Using drip irrigation prevents moisture extremes. Proper watering encourages healthy calcium uptake and prevents blossom end rot issues.

Preventing Blossom End Rot

Preventing Blossom End Rot
Water deeply, about 1-2 inches per week, to encourage healthy root growth. Use drip irrigation or soaker hoses to provide uniform moisture to the roots. Mulch around plants after fruit sets to retain soil moisture and reduce water evaporation.

Healthy roots are key to preventing blossom end rot. Encourage extensive root growth by providing adequate, consistent moisture. Mulch helps moderate soil moisture while protecting surface roots from drying out.

Care for the roots by avoiding damage after fruit sets that could hinder the plant’s ability to take up water. With deep, infrequent watering, mulch, and undisturbed roots, you can help prevent troubling blossom end rot.

Water Deeply

Frequently check the soil and water deeply when it is dry a couple inches down. Using your fingers or a soil probe, test moisture daily. When the top few inches are dry, soak the soil about 6-8 inches deep. Tomato plants need consistent moisture for transporting calcium.

Infrequent, deep watering encourages deep roots and steady nutrition flow. Prevent blossom end rot in your vitamin C-rich fruits through attentive, thorough irrigation.

Use Mulch

Add a 2-4 inch blanket of mulch around your plants, like a cozy comforter tucking in the soil’s moisture.

  1. Mulch retains moisture and protects roots.
  2. It moderates soil temperature.
  3. Mulch suppresses weeds.
  4. As mulch breaks down, it improves the soil.

Spreading organic mulch around your tomato plants mimics a forest floor, insulating soil moisture and nutrients. The mulch layers conserve water, reducing blossom end rot. Select fine shredded bark, straw, leaves, or compost to nourish your tomatoes.

Care for Roots

Treat those roots tenderly, as they nourish your tomatoes.

Coddle tomato roots with care. They are the lifeline, drawing soil nutrients and moisture to nourish fruits.

Gentle Handling
Minimize digging nearby Keeps structure intact
Avoid tilling beneath Preserves tiny root hairs
Mulch gently in place Reduces compaction
Water at base, not on leaves Leaves roots undisturbed
Spread water broadly Encourages wide growth

Fixing Existing Blossom End Rot

Fixing Existing Blossom End Rot
Alright, listen up. If you’ve already got full-blown blossom end rot on your tomatoes, you need to remove and discard affected fruit right away to limit the spread. Then mix some calcium supplements into your soil or use a foliar spray to give your plants an immediate calcium boost and help prevent new fruit from developing the rot.

Remove Affected Fruit

Let’s nix those nasty lookin’ fruits with the rotten bottoms pronto, sugar.

  1. Inspect plants daily for initial sunken brown spots.
  2. Remove affected fruit immediately to deter spread.
  3. Discard damaged tomatoes completely – no nibblin’!

Promptly pluckin’ poor fruit prevents persistent problems. Examine your plants closely each day, keeping keen eyes peeled for telltale sunken spots. Swiftly discard fully affected tomatoes, roots and all – no savin’ or snackin’ on those sad spuds.

Remaining fruits still stand a chance, so persist in your vigilance for victory over blossom end rot.

Supplement Calcium

Y’all better supplement that calcium pronto if you want those tomatoes to keep growin’ strong, sugar! Easy ways to add more of this critical mineral are to mix crushed eggshells or bone meal into the dirt around your plants.

You can also water with liquid calcium supplements or composted manure to give your tomatoes all the calcium they’re craving. Keeping the soil moist with regular deep watering helps the roots take up those supplements.

With these straightforward tips, you’ll be harvesting hearty tomatoes all season long instead of seeing nasty rotten bottoms on your fruits.

Calcium Sources for Tomatoes

Calcium Sources for Tomatoes
You can give your tomatoes a calcium boost by working crushed eggshells and bone meal into the soil or using organic calcium fertilizers. Composted manure and lime also add calcium while improving the soil. Focus on maximizing calcium delivery to the roots early in the season for the healthiest plants.

Use foliar sprays like calcium chloride or calcium nitrate once blossom end rot appears to immediately increase calcium.

Test your soil pH yearly, amending to maintain 6.0-6.5, the ideal range for proper calcium uptake. Mix in amendments like lime several weeks before planting. Supplement irrigation with calcium-rich rainwater harvesting.

Go beyond just treating this tomato rot by planning ahead to ensure adequate calcium next season. Consistent moisture and undisturbed roots are just as key as calcium supplements to prevent blossoms from developing this deficiency.

With smart prevention tactics and immediate treatment, you can keep your tomatoes safe from this culprit.

Choosing Rot Resistant Varieties

Choosing Rot Resistant Varieties
Opt for rot-resistant tomato varieties like cherry, grape, Celebrity, and Early Girl to help circumvent issues.

  1. Check with your local extension lab for the top regional picks that’ve proven rot resistance.
  2. Prioritize heat and drought tolerant varieties that can better handle fluctuations in moisture.
  3. Select small fruited tomatoes like cherry and grape types, which rarely get blossom end rot.

The right tomato variety can help you avoid frustrating mushy blossom end rot, even in high heat. Choose options bred to thrive in your growing season and climate. Make watering easier on yourself by planting tomatoes that tolerate moisture soaks and dry spells.

With smart variety selection as your foundation, consistent irrigation, and attentive soil care, you can sidestep this rot culprit.

When to Call for Expert Help

When to Call for Expert Help
Can’t quite kick blossom end rot? Consult a local university extension office or master gardener for their insights. They have years of experience diagnosing tricky tomato troubles in your growing zone.

Describe the mushy damage and share details on your soil, watering, and varieties.

With blossom end rot, the developing fruit lacks adequate calcium. The expert can assess if your irrigation patterns or soil conditions hinder calcium uptake. Or if varieties prone to the rot were selected. The goal is to pinpoint why calcium delivery to rapidly expanding fruit falters, causing tissue breakdown.

Collaborate with your local experts to grow abundant, well-formed fruit. Their tailored recommendations address your garden’s unique needs. With their guidance, you can correct the specific deficiencies fueling frustrating rot.

Partner with these knowledgeable resources so next season brings your biggest, healthiest tomato harvest yet.

Frequently Asked Questions (FAQs)

How long does it take for blossom end rot to appear after a calcium deficiency starts?

Blossom end rot typically appears 7 to 10 days after the calcium deficiency begins. Look for the first signs of brown, sunken areas on the bottoms of fruit about a week after a period of drought or other stress.

The damage gradually spreads and worsens if the deficiency continues unchecked. Act promptly at the first sign to limit impacts.

Can you still eat tomatoes affected by blossom end rot?

You can still eat tomatoes with blossom end rot, but should you? Cut away the damaged portions to enjoy the rest of the fruit. Focusing on prevention and optimal growing conditions creates the tastiest, healthiest harvest.

Providing deep, consistent watering and calcium gives tomatoes their best chance to thrive.

Is blossom end rot contagious to other plants?

Blossom end rot is not contagious to other plants. It’s caused by irregular moisture and calcium deficiency in the affected plant. Focus on improving watering consistency and soil nutrition for the struggling tomatoes.

Will adding calcium supplements to the soil help existing affected fruits?

Unfortunately, calcium sprays or soil supplements won’t cure fruits already showing blossom end rot. Focus efforts on maintaining optimal soil moisture and calcium levels to protect new fruit production.

If my tomatoes had blossom end rot last year, will it happen again this year?

You may see blossom end rot again this year if conditions are right, but you can prevent it. Focus on deep, consistent watering and mulching early in the season. Test and amend your soil if needed. Select resistant varieties and pick fruits promptly when ripe. With good care, you can still get a bountiful harvest.


Though Blossom End Rot may walk through your garden, you need not fear it. Arm yourself with knowledge of its causes and treatments. Water deeply, mulch religiously, and supplement calcium as needed. Going forward, choose resistant varieties.

Call the local extension office forthwith if the rot persists. Vigilance and care will see you prevail against this scourge and claim your tomato harvest.

Avatar for Mutasim Sweileh

Mutasim Sweileh

Mutasim is a published author and software engineer and agriculture expert from the US. To date, he has helped thousands of people make their yards lush and thick.