Nothing is more upsetting to a gardener than dutifully caring for your plants only to find issues once the plant has begun to set fruit. Blossom End Rot is one of many common problems gardeners will encounter. It often occurs on common beginner gardener plants. Just because they’re easy to grow, however, doesn’t mean that we don’t run into problems with them from time to time.

What is Blossom End Rot?

Blossom end rot (also called BER) occurs at the end of a tomato where the flower used to be. Fruit that is affected is usually about halfway grown when blossom rot appears. As the fruit begins to ripen, blossom rot becomes more pronounced. It will slowly travel up toward the stem until the whole fruit has rotted.

BER often (but not always) affects the first set of developing fruit. As such, is easy to quickly identify. That makes it possible to save the fruit that will ripen later in the growing season.

What Plants are Affected by Blossom End Rot?

• Tomatoes
• Peppers (including hot varieties like cayenne peppers)
• Squash (including cucumbers, zucchini, eggplant, pumpkins, etc.)
• Melons

What Causes Blossom End Rot?

Blossom rot may appear to be a fungal or disease issue, but it is entirely caused by a calcium deficiency. There are a few possible causes for blossom end rot, but the main problem is your plants are unable to utilize calcium from their soil.  Calcium is a much-needed element for tomatoes and other plants to survive. It is pivotal for the plants to regulate its moisture systems. It also holds together cell walls and membranes and assists with the production of pollen.  Calcium works with salts to help to manage the water movement throughout the plant’s vascular system.  There are several reasons that your plants may not be getting enough calcium:

Not Enough Calcium in the Soil

Obviously, if there’s not enough calcium in your soil, then your plants won’t be able to utilize it. When you’re planting seeds or transplanting seedlings in the spring, make sure your soil has enough calcium. You can add calcium to your soil naturally (see below) and prevent future occurrences of Blossom End Rot.

Your soil may have started out with enough calcium in the soil. However, your plants can use it up in the course of a single gardening season or less. Too many plants in a small area or container garden will leach calcium from the soil faster than usual. If you have the space, plan your garden to give enough space between plants. Space between plants can help to mitigate leaching the soil too quickly of calcium and other elements.

Too Much of Other Elements in the Soil

While lack of calcium is the main cause of Blossom End Rot, it is not the only possible culprit. Your garden soil may have enough calcium, but could also be too rich in other elements. This nutrient imbalance could lead to Blossom End Rot.

Nitrogen is a key element to causing your plants to grow quickly and large. It encourages the plant to produce chlorophyll and plant cells. Too much nitrogen potentially unbalances the nutrients in the plant. Plants will produce a great deal of cells and growth. But without the calcium it is less able to sustain sufficient cell wall strength. This causes Blossom End Rot.

Potassium helps plants intake water and nutrients. It helps them to move the nutrients throughout the plant and incorporate them where the need it. However, in high quantities, this effect is reversed. Plants with too much potassium can’t take in the nutrients they need and the plants end up starving.

Magnesium is like potassium in that it helps the plant take in nutrients. It also aids in chlorophyl production and helps the plant produce glucose. Too much magnesium, however, stunts plant growth and clogs the veins of the plant’s vascular system. Essentially, too much magnesium amounts to too much salt. This makes it harder for the plant to take in and utilize water and the other nutrients.

Improper Watering

Improper watering practices can cause Blossom End Rot too. Too much water, too little water, or inconsistent watering will all cause issues for developing fruit.

A lack of water in the soil will make it difficult for your plant to take on nutrients including calcium. Essentially, the root cause (pun intended) is the same: the plant isn’t getting enough calcium. But while there may be enough calcium in the soil, if the plant is receiving too much or too little water, it will be unable to utilize that ready calcium.

Too much water may cause a dilution of nutrients. Too little water and the plant’s veins may not be able to carry the necessary nutrients where they need to go. Balance is the key to maintaining proper plant health.

Can You Cure Blossom End Rot?

No. Unfortunately, you cannot cure blossom end rot on fruit that already shows signs. The plant cannot repair this fruit and the fruit cannot heal itself. The best you can do is remove the affected fruit and fertilize your soil to prevent future recurrence. By fertilizing your soil, you will give your plants the nutrients they need to produce fully-formed fruit that will appear on the plants later in the season. Fruit developing but not yet ripe or not yet showing signs of BER will also benefit from the additional nutrients.

Mid to late summer is the perfect time to give your soil the additional fertilizer your plants need to make it through the rest of the growing season. If you’re unsure what nutrients your soil is lacking, you can always pick up a soil test kit. Your local nursery or plant section of your local hardware store should have it. Soil test kits tell you for certain what your soil is missing. Testing will give you an idea of what you can do to augment the soil for your plants’ benefit.

How to Add Calcium to Your Soil

To address the usual cause for BER, here’s a few ideas to add calcium to your next round of watering. Good news! You probably already have the necessary ingredients in your kitchen to start adding calcium to your soil.

Egg Shells

Eggshells are an ideal source of calcium for the garden. Bonus that they’re worthless to us in the kitchen and are typically thrown away. Save your eggshells whenever you use them to give your garden a boost. Want to know more? [Follow these steps for using eggshells to add calcium to your garden.]

Powdered Milk

Powdered milk is another common ingredient chock-full of calcium. As kids we were all told to drink our milk because it is high in calcium and will make us grow strong. This is as true for your plants as it is for you. Mix powdered milk into your watering can and water your plants at the soil level.

Be careful not to get any on the leaves if you can. Otherwise, leaves will show milky stains of calcium left behind when the water evaporates. While not overwhelmingly dangerous to the plant, the calcium can clog the stomata on the top of the leaves. This can make it difficult for the plant to breathe. Also, the plant can’t utilize any calcium that isn’t first dissolved in water and taken in by its roots.

Can You Eat Fruit with Blossom End Rot?

Once you cut away the rotted affected portion of the fruit, the rest of the fruit is edible. However, in most cases, blossom end rot affects a full third to half of the fruit. That makes it practically worthless to save only the remaining unaffected portions. Blossom End Rot may also cause the interior of the fruit to appear deformed. Seeds may also rot or appear mal-formed. So, in most cases, don’t eat fruit affected with BER, but throw away or compost affected fruit.

As stated above, BER is not a fungal, pest, or disease problem, but a problem of nutrient deficiency. That means that affected fruit is safe to throw into your compost.

Conclusion

Blossom End Rot is a common problem that is easily prevented and remedied with the right application of fertilizer. Now that you know all about it, you’re ready to combat this issue with ease. Have you had blossom end rot in your garden? Tell us all about it in the comments!

Related Reading

If you came across this page in an attempt to diagnose an issue with your tomatoes, you’ll want to check out this post about Common Tomato Problems, too.