Some things to check: First the pot, does it have drainage holes at the low points? If not-- drill holes. Is it the right size for the plant? If you have a dwarf windowbox then 2 gallons might be OK. Second the Mix, does it drain without holding water too long? If not, then repot with appropriate draining mix. Did you have a COMPLETE fertilizer in your initial potting mix including calcium? make sure you do. Next; were you watering when the plant needed it, or on a predetermined schedule? Check moisture at root level with your finger, and look at the plant for wilt. Dont water unless the plant needs it. Are you giving the plant a periodic fertilizer after the initial fertilizer is depleted? The watering of containers with fast draining mix will deplete fertilizer faster than in the ground plants. Consider these questions and how many of these things need to be addressed. This is a a little late in the season for some locations, so some special things may have to be considered due to remaining growing time. Of course one needs to assure the plant has good sunlite and right temperature.

If you're watering too much depends on the size of the emitters, the size of the garden, etc... Take the size of your garden in square feet and multiply by 0.09. That is how much water you need per day in gallons. For example, my garden is 40 x 80. I need 288 gallons per day. Now take the size of your emitters and multiply by the GPH rating. My plan is 333 .5 GPH emitters, 53 1 GPH emitters, and 33 1.5 GPH emitters. 333*.5+52*1+33*1.5= 269 Divide the gallons needed per day by the result of the emitters and multiply by 60 for the number of minutes a day watering needed. 288/269*60=64 minutes It should be a lot less if you mulch well and concentrate the water on the plants with drip. Hope this helps. Rick

Put epsom salts around your tomatoes when you plant them and your Bossom end rot is gone regardless of what the actual cause is . I suspect that the calcium up take , which in turn provides further nutrients , is upset because of inconsistant moisture . Too much , then not enough , Etc.Cool and damp. I am not a chemist so I cant argue the potassium/ phosphorus over use as a cause.However i use soft rock phosphate , bone meal , fish inards , banana rich compost greensand and wood ashes. The ph is about6.5-6.8.The epsom salts makes the difference. About a half tablespoon per plant in a ring about 3 inches out from the stem.I have not had a BER tomato in years . I have grown on both sand and clay. Same problem , same treatment , same results.I use the same type salts that i soak my feet in Happy Matering johnny

Blossom-end rot is a disorder of tomato, squash, pepper, and all other fruiting vegetables. You notice that a dry sunken decay has developed on the blossom end (opposite the stem) of many fruit, especially the first fruit of the season. This is not a pest, parasite or disease process but is a physiological problem caused by a low level of calcium in the fruit itself. Symptoms BER, or blossom-end rot usually begins as a small "water-soaked looking" area at the blossom end of the fruit while still green. As the lesion develops, it enlarges, becomes sunken and turns tan to dark brown to black and leathery. In severe cases, it may completely cover the lower half of the fruit, becoming flat or concave, often resulting in complete destruction of the infected fruit. Cause Calcium is required in relatively large concentrations for normal cell growth. When a rapidly growing fruit is deprived of calcium, the tissues break down, leaving the characteristic lesion at the blossom end. Blossom-end rot develops when the fruit's demand for calcium exceeds the supply in the soil. This may result from low calcium levels in the soil, drought stress, excessive soil moisture, and/or fluctuations due to rain or overwatering . These conditions reduce the uptake and movement of calcium into the plant, or rapid, vegetative growth due to excessive nitrogen fertilization. Management Adequate preparation of the garden bed prior to planting is the key to preventing BER. Insure adequately draining soil in the bed by adding needed ammendments, maintain the soil pH around 6.5 - a pH out of this range limits the uptake of calcium. Lime (unless the soil is already alkaline), composted manures or bone meal will supply calcium but take time to work so must be applied prior to planting. Excess ammonial types of nitrogen in the soil can reduce calcium uptake as can a depleted level of phosphorus. After planting, avoid deep cultivation that can damage the plant roots, use mulch to help stabilize soil moisture levels and help avoid drought stress, avoid overwatering as plants generally need about one inch of moisture per week from rain or irrigation for proper growth and development. Once the problem develops, quick fixes are difficult. Stabilize the moisture level as much as possible, feeding with manure or compost tea is recommended by many, foliar applications of calcium are of questionable value according to research because of poor absorption and movement to fruit where it is needed but many have reported that foliar application of magnesium (epsom salts) can effect added calcium uptake. Other various suggestions consist of powdered milk, crushed egg shells tea, bone meal tea, Tums tablets, etc. but prevention is the key. Some recommend removing affected fruit from to reduce stress in the plant. BER should not be confused with fruit abortion or inadequate pollination although the symptoms may appear similar. The onset of BER occurs only after the fruit is well on it's way to development while insufficient pollination problems terminate the fruit while still quite small.