Why do my cucumbers taste bitter? What causes blossom end rot? Find answers to common garden problems and solutions to keep your garden producing nutritious and tasty produce.
Organic vegetable gardening has been a passion of mine for most of my life. As much joy as it gives me, I’ll be the first to admit that a few aspects can be particularly challenging: insects, animal pests, plant diseases, and the frustrating things that happen because of the weather. On top of these common issues, other challenges and oddball gardening problems have troubled me over the years: Why did the leaves on my seedlings turn white? How do I protect my vegetable crops during heat waves? Why did the little squash on my zucchini plant fall off?
I knew I wasn’t the only gardener wondering about these things, so I decided to write about them in The Vegetable Garden Problem Solver Handbook. In it, I cover how to nurture your plants so they’ll produce well and be less likely to have problems, how to deal with the challenges Mother Nature throws your way, and the disorders that can affect your plants, even when diseases aren’t to blame. I want gardeners to enjoy growing their own food and to have a straightforward guide they can consult when problems arise. So, here’s how to identify, prevent, and remedy some common physiological problems, meaning they’re caused by environmental conditions rather than pests or diseases.
Why Do my Cucumbers Taste Bitter?
Have you ever picked a cucumber, expecting a delicious flavor, only to discover it was extremely bitter? Or harvested lettuce for a summer salad, but the lettuce tasted awful? These issues are caused by environmental stresses. Cucumbers and other cucurbits contain natural chemicals called “cucurbitacins.” Environmental conditions, such as extended periods of high temperatures or even cooler-than- usual temperatures, cause cucurbitacin levels to rise, resulting in bitter fruits. Irregular watering is another trigger for this. For example, if a gardener only waters the plants periodically, it stresses them. Low soil pH is another potential cause of bitterness.
Crops most impacted: Primarily cucumbers, but also other members of the cucurbit family (melons, pumpkins, squash), lettuce, and other leafy greens.
Bitterness Solution
- Water your plants regularly.
- Pick cucumbers while they’re young and most flavorful.
- In cucumbers and other cucurbits, the majority of the bitterness is located at the stem end of the fruits. If you remove that area and peel the skin, the fruits should be more palatable.
- Consider growing hybrid cucumbers, because bitterness occurs less frequently in them.
- Mulch around lettuce and other salad greens to help the soil retain moisture.
- Use shade cloth to extend cool-season crops’ growing season into summer.
What Causes Blossom End Rot?
Blossom end rot is most easily recognized by the presence of a sunken, brown bottom tip on the developing fruits of tomatoes and zucchinis, but it can also occur on other crops. The underlying problem is a calcium deficiency within the developing fruits. The primary causes are hot, dry conditions and irregular watering. For fruits to develop normally, plant roots need to be able to transport calcium from the soil into the plants and up to the fruits. To do that, the roots require moisture.

Overuse of high-nitrogen fertilizers also causes blossom end rot because they promote leafy growth, which robs calcium from the fruits. You might think applying calcium to your soil is the answer, but if the soil around the plants isn’t watered regularly, there’s no way for the calcium to get into the plants through the roots. Foliar applications of calcium won’t help either, because calcium isn’t able to move from the leaves to the fruits. While blossom end rot can affect nearly every variety of tomato, it impacts elongated plum tomatoes the most. Cherry tomatoes typically aren’t affected by it at all.
Crops most impacted: Cucurbit family crops (melons, pumpkins, summer and winter squash) and nightshade family crops (eggplants, peppers, tomatoes).
Blossom End Rot Solution
- Water your plants consistently, and increase the watering time during exceptionally hot, dry conditions.
- Place mulch around the base of susceptible crops to help the soil retain moisture. Ideal materials include shredded leaves or grass clippings from a lawn that hasn’t been treated with herbicides.
- Avoid overfeeding your plants with high-nitrogen fertilizers.
- Don’t cultivate near the roots of susceptible crops, because damaged roots won’t transport as much calcium into the plants as heathy roots.
- Use shade cloth during excessive heat to shelter susceptible plants from the intensity of the sun.
- Most soil contains sufficient calcium for growing vegetables. If your plants suffer from blossom end rot every year and you’re consistent about watering, test your soil before adding calcium.
What is Bolting in Plants?

Bolting refers to plants blooming and setting seeds for the next generation before their growing season is over. Cool-season crops are more susceptible to this, and it most frequently occurs when the day length and temperatures increase. Yet, it can also happen when plants are suddenly exposed to cool temperatures or when plants struggle because of a lack of space, insufficient sunlight, or insect or disease problems. Once plants bolt, they’ll stop producing new leaves.
Crops most impacted: Bok choy, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, cilantro, lettuce and other greens, onions grown from sets or plant starts, and radishes.

Bolting Solution
- When seed shopping, look for varieties labeled “slow to bolt” or “bolt resistant.”
- Plant cool-season crops as soon as conditions are right to allow them enough time to grow and produce before the hot weather arrives. If you missed that opportunity, consider planting that crop in late summer and harvesting it in fall.
- Water your plants consistently.
- Avoid disturbing the plants’ roots, as this can trigger bolting. Many of these crops fare much better when their seeds are sown directly in the garden.
- If you catch the problem early enough, you might be able to pinch off the flowers and keep the plants going for a bit longer, but the plants will be on
borrowed time. - Those gardening in regions with hot summers can protect susceptible crops with lightweight (30 percent) shade cloth.
- If you don’t need to replant the bed, help the pollinators by letting the bolted plants bloom.
Blossom Drop Problem
Blossom drop results from a lack of pollination caused by environmental conditions. Ideal daytime temperatures for pollination range between 70 and 85 degrees Fahrenheit. If it’s too cold or too hot, the unpollinated flowers will drop off. In addition, excessively low or high relative humidity affects the mobility of pollen; levels between 40 percent and 70 percent are optimal. Other causes include windy conditions that dry out the flowers, planting warm-season crops too early or where they don’t receive enough sunlight, irregular watering, or too much nitrogen fertilizer, which makes plants use their energy for leaf development rather than flowers. Even pest or disease problems will cause blossom drop, because stressed plants produce fewer flowers. The good news is that blossom drop is usually a temporary disorder that will resolve as weather conditions improve.

Crops most impacted: Beans, nightshade family crops (eggplants, peppers, tomatoes).
Blossom Drop Solution
- Plant warm-season crops after the danger of frost has passed. If you planted them too early, cover them with floating row covers for some protection.
- Make sure they’re planted in a location that receives at least 6 to 8 hours of sunlight daily.
- Water your plants regularly to keep the soil lightly moist.
- Cover plants with lightweight (30 percent) shade cloth when temperatures are unusually hot.
- If your garden is in a windy location, protect plants with a barrier to prevent flowers from drying.
- Avoid repeated use of high-nitrogen fertilizers.
- Choose varieties that perform well in your region. If your summers are extremely hot, select varieties that mature in a shorter period of time.
Fruit Cracking Problem
Most gardeners have seen this problem on their tomatoes, but fruit cracking can occur on several types of vegetable crops. The most common cause is rainfall or excessive watering following prolonged dry spells. The problem is that the skin of the fruit is unable to expand with the rapidly growing inner tissue. Unfortunately, the exposed tissue is more prone to rotting and deterioration. It’s not uncommon for a beautiful head of cabbage to suddenly split wide open after a summertime rainstorm or even from the heat – usually right before you intended to pick it! Fortunately, the head is still salvageable if you harvest it right away. Root crops, such as carrots and parsnips, are also susceptible to cracking as a reaction to changing moisture in the soil. No matter which crops you’re growing, cracking happens more frequently in fruits that are reaching maturity.

Crops most impacted: Cabbage, carrots, cucumbers, nightshade family crops (eggplants, peppers, tomatoes), parsnips, watermelons.
Fruit Cracking Solution
- Water your garden consistently, but don’t overwater.
- Place mulch on the surface of your beds to help the soil retain moisture.
- During especially hot summers, suspend a lightweight (30%) shade cloth over susceptible crops.
- Allow leaves to cover developing fruits, to provide some protection.
- Harvest some of your fruits and vegetables a bit early – especially if rain is in the forecast – and allow them to ripen indoors. This works especially well with tomatoes that are just starting to show a bit of color.
Sunburn (aka ‘Leaf Scorch’) Problem
While you might think only people get sunburns, it happens to plants as well, and can be much more devastating. At the very least, the plants will struggle, but if the damage is severe enough, they’ll die.
With sunburn, the leaf tissue turns white or brown and usually wilts. It’s not unusual for sunburn to impact young seedlings. Sunburn most commonly occurs when gardeners fail to acclimate seedlings to direct sunlight and outdoor temperatures before moving them permanently out to the garden. There’s a huge difference between the amount of light an indoor grow light puts out and the intensity of the sun outdoors.
Because the leaves of young seedlings are tender, it’s important to put them through the hardening-off process to acclimate them to the great outdoors.
Crops most impacted: Young seedlings of most vegetable crops.

Sunburn Solution
- Harden off your seedlings over the course of a week: On the first day, move your seedlings outside to an area with filtered sunlight for one hour, and then move them back inside. On the second day, move them out for two hours and bring them back indoors. Each subsequent day, add an hour to their outdoor time while moving them into brighter sunlight. This might sound tedious, but it’ll be well worth your time. By the end of those seven days, it’ll be safe to transplant your seedlings into the garden.
- If you didn’t harden off your seedlings before transplanting them and they’re exhibiting mild cases of sunburn, place a shade cloth above the bed for a few days to give them some relief. Don’t remove the damaged leaves, because they should still be able to conduct photosynthesis, which will help the plants recover.
- Water plants regularly to reduce stress on them.
- If you have advance warning about a heat wave, use shade cloth to protect susceptible plants.
This excerpt is from The Vegetable Garden Problem Solver Handbook (Cool Springs Press).