When it comes to plant health, few things are more disheartening than seeing your harvests ruined by rot. Whether it’s bud rot, gray mold, or the notorious blossom end rot, these conditions can devastate your crops if left unchecked. The good news? You can take proactive, organic steps to prevent, manage, and even reverse some of the damage.
This guide covers how to identify each type of rot, what causes them, and how to handle them using natural and DIY-friendly solutions.
🧬 What Are Bud Rot, Mold, and Blossom End Rot?
🔴 Blossom End Rot (BER)
Type: Physiological disorder (not a disease)
Common Crops: Tomatoes, peppers, squash, eggplants
Symptoms: Dark, sunken spots on the blossom end (bottom) of fruit. Flesh may appear leathery or mushy.
🌫️ Bud Rot (Botrytis)
Type: Fungal disease
Common Crops: Cannabis, tomatoes, squash, sunflowers, ornamental flowers
Symptoms: Gray, fuzzy mold starting at the bud center. Buds become mushy, brown, and eventually die.
⚫ Mold (Gray Mold, Botrytis cinerea)
Type: Fungal disease
Common Crops: Berries, tomatoes, beans, flowers
Symptoms: Soft, brown spots that grow fuzzy gray mold. Affected tissue wilts and collapses.
🌧️ What Causes These Issues?
| Problem | Primary Cause | Contributing Factors |
|---|---|---|
| Blossom End Rot | Calcium deficiency in fruit tissue | Irregular watering, excessive nitrogen, pH imbalance |
| Bud Rot | Botrytis fungus thriving in humid, still air | Poor airflow, dense foliage, overwatering |
| Mold | Fungal spores + high humidity | Rainy weather, tight spacing, damaged fruit or leaves |
🔍 How to Identify the Issue
| Sign | Likely Issue |
|---|---|
| Soft, sunken brown end of tomatoes or peppers | Blossom end rot |
| Gray fuzz inside cannabis or flower buds | Bud rot |
| Fuzzy mold on fruit or leaves | General mold (Botrytis) |
| Wilting flowers or fruit collapse | Botrytis or advanced BER |
Pro tip: If it looks fuzzy, it’s likely fungal. If it’s leathery and sunken without mold, it’s likely nutrient-related (BER).
🌱 Organic & DIY Prevention Methods
🛑 How to Prevent Blossom End Rot
- Consistent Watering
- Keep soil evenly moist—avoid letting it dry out and then overwatering.
- Use mulch to regulate moisture.
- Check Soil pH
- Optimal pH: 6.2–6.8
- Use a home pH test kit and amend as needed with lime (to raise pH) or sulfur (to lower it).
- Boost Calcium Naturally
- DIY calcium booster: Crush eggshells or oyster shells, dry, grind, and add to soil.
- Diluted milk or whey (1:1 with water) can also be used as a foliar spray for added calcium.
- Avoid Over-Fertilizing with Nitrogen
- Too much nitrogen encourages leafy growth and disrupts calcium uptake. Choose balanced or low-nitrogen fertilizers.
🌬️ How to Prevent Bud Rot and Mold
- Improve Airflow
- Prune inner foliage to allow better airflow through dense plants.
- Space plants adequately and avoid overcrowding.
- Avoid Overhead Watering
- Water at the base of plants, ideally in the early morning.
- Use drip irrigation or a soaker hose.
- Harvest Carefully
- Remove damaged, overripe, or moldy fruit immediately.
- Harvest buds or flowers as soon as they mature to avoid rot.
- Use Natural Sprays
- DIY Fungicide Spray:
- 1 tbsp baking soda
- 1 tsp mild liquid soap
- 1 qt water
- (Optional: Add 1 tbsp of neem oil)
- Spray every 7–10 days
- DIY Fungicide Spray:
- Plant Resistant Varieties
- Look for BER-resistant tomatoes or mildew-resistant squash varieties.
🧪 Soil and Plant Health Support
- Compost Tea: Boosts beneficial microbes that compete with harmful fungi.
- Liquid Seaweed or Fish Emulsion: Gentle, balanced nutrition to support overall plant resilience.
- Mycorrhizal Fungi: Helps roots absorb nutrients more efficiently and improves soil biology.
✂️ What to Do If You Already Have Rot
💀 Blossom End Rot
- Remove affected fruits to redirect energy toward healthy growth.
- Check watering and calcium levels.
- Add crushed eggshells or calcium chloride around the root zone.
🧹 Bud Rot
- Cut out infected buds immediately—dispose of them far from your garden.
- Sterilize your pruners between cuts with hydrogen peroxide or rubbing alcohol.
- Increase airflow and reduce humidity as much as possible.
👃 Gray Mold (Botrytis)
- Remove affected leaves/fruit ASAP.
- Treat with neem oil, sulfur sprays, or baking soda solution.
- Don’t compost moldy plants—dispose of them to avoid reinfection.
💡 Bonus DIY: Calcium Spray for BER Prevention
What You’ll Need:
- 1 tablespoon of calcium chloride or calcium nitrate
- 1 gallon of water
- Spray bottle
Instructions:
Mix and apply as a foliar spray in the morning every 5–7 days during fruit development. Avoid spraying during full sun.
📅 When to Watch Out
| Issue | Peak Season |
|---|---|
| Blossom End Rot | Early to mid summer (fruiting phase) |
| Bud Rot | Mid-late summer, especially in humid areas |
| Mold | After rain, during long humid periods |
🧠 FAQs
Q: Can you eat fruit with blossom end rot?
A: Yes, you can cut off the damaged part. The rest is safe if it’s mold-free.
Q: Is bud rot contagious?
A: Yes. Botrytis spreads through spores, especially in moist environments. Remove infected plant material immediately.
Q: Can I compost moldy plants?
A: No. Spores can survive and reinfect the next season. Always discard infected material in the trash.
Q: Can I reverse blossom end rot mid-season?
A: You can stop it from affecting new fruit by fixing calcium and watering issues. Damaged fruits won’t recover.
✅ Summary: Prevention First, Treatment Second
| Issue | Fix | Prevent |
|---|---|---|
| Blossom End Rot | Add calcium, consistent watering | Mulch, balanced fertilizer |
| Bud Rot | Prune, increase airflow, remove rot | Proper spacing, early harvest |
| Mold | Spray fungicide, remove infected parts | Avoid moisture on leaves, improve drainage |
🏡 Final Thoughts
Bud rot, mold, and blossom end rot may sound like a gardener’s nightmare—but they’re entirely preventable with consistent care, good airflow, and healthy soil practices. By staying vigilant and using organic tools and DIY fixes, you can keep your harvests mold-free and bountiful.