Vegetables

Put an End to Blossom-End Rot: Water and Nutrient Management is Key

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By Nora Doonan, UConn Soil Science Graduate Student, Department of Plant Science & Landscape Architecture

5 ripe tomatoes
Photo by Julie-Ann Adorno, Soil Science Graduate Student, UConn Plant Science & Landscape Architecture

It can be frustrating to put time and energy into growing tomatoes, only to find that your tomatoes have developed blossom-end rot. Blossom-end rot is a physiological disorder that commonly affects tomato plants, characterized by a black, sunken spot on the fruit. This disorder is caused by insufficient calcium as a result of nutrient and water management challenges. Blossom-end rot can also affect peppers, eggplants, squash, and watermelons. In tomatoes, it is commonly seen on larger and elongated varieties, which can have a greater demand for calcium. Calcium is an essential plant nutrient that is required for proper growth, especially for the development of cell walls in the tomato fruit. When a fruiting tomato plant experiences calcium deficiency, the cell wall can collapse and show the appearance of blossom-end rot. Soil tests can reveal if your soil has sufficient levels of calcium and can determine if your soil pH is optimal for nutrient availability.  

Oftentimes, the soil is sufficient in calcium levels, but blossom-end rot still occurs. Blossom-end rot can be closely associated with soil moisture that is too wet or too dry. The soil should never dry out completely. It is important to water regularly to ensure that plants receive 1 to 2 inches of water a week. A cycle of dryness followed by overwatering is only promoting calcium deficiency in the plant. If soil is too saturated, there may be insufficient oxygen levels in the soil that can affect the roots’ ability to take up water and nutrients.  

One method of maintaining optimal soil moisture is to mulch tomato plants with an organic mulch, such as wood chips or straw, after the soil has warmed up. This will help to prevent excessive evaporation and drying of the soil. Another method is to plant tomatoes in a mound of soil that is high in organic matter or compost. Organic matter can retain soil moisture and provide adequate drainage.  

There are other factors that can affect calcium uptake by the plant, such as high concentrations of ammonium, potassium, and magnesium in the soil. This can be caused by over fertilization. Specifically, over fertilizing with nitrogen can promote excessive production of leaves in the tomato plant, which can preferentially distribute calcium to the leaves rather than the fruit.  

Calcium movement in the plant is dependent on transpiration, which is the loss of water to the atmosphere from plant leaves, stems, and flowers. Calcium is taken up through the roots and relies on water flow through the xylem for transport through the plant. This movement of water through the xylem is driven by the process of transpiration. Calcium is not redistributed from the leaves to the fruit. In addition, the overfertilization of ammonium, potassium, and magnesium can allow for competition in root uptake of calcium because they are all positive cations. Damages to roots, caused by fertilizer burns or cultivation, can also be a factor in impairing nutrient and water uptake. To prevent blossom-end rot through fertilization practices, apply fertilizer as recommended by a soil test and apply nitrogen fertilizers in the form of nitrate, rather than ammonium.   

Any affected fruits can be removed from the plant, as they will continue to drain moisture and calcium for development from other fruits. A foliar application of calcium can be made to the leaves when the fruit is young, but it is not the most effective method, since calcium in the leaves is relatively immobile. The goal is to prevent the need for foliar application through water and nutrient management across the tomato plant growth stages. Hopefully these methods will allow you to prevent blossom-end rot starting at beginning stages of growth, so that you can enjoy a bounty of beautiful, red tomatoes.  

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at cahnr.uconn.edu/extension/locations. 

This article was published in the Hartford Courant June 14, 2025

Why Are Seeds Sprouting in My Tomato?!

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Nick Goltz, DPM, UConn Home & Garden Education Center, UConn Plant Diagnostic Lab

A tomato sliced in half with seedlings sprouting up
Seed germination within an overripe tomato. Photo credit: J. Copes.

UConn Home and Garden Education Center alum Carol Quish wrote a short blog post about vivipary in 2014 that, over a decade later, is still one of our most-read pieces. Why are folks still interested to read this post after so much time? Because seeing seed vivipary in a tomato you’re about to eat is just so darn weird. To better discuss and understand vivipary however, we should start with a little refresher on seed biology.

Reflecting back on 4th period science class with Mr. So-and-so, you’ll recall that producing  a seed is both a distribution and reproduction strategy for plants. Generally, a seed is composed of a developing young plant called an embryo and a nutritious tissue to support the embryo called an endosperm, both of which are encapsulated within a hard seed coat. When an embryo is triggered to begin growing and breaks through the seed coat, many people consider this the stage of germination.

A seed will typically be in a state of dormancy while within the fruit and for a period after fruit harvest and dispersal. This strategy of undergoing dormancy is usually advantageous to the seed so it does not germinate and begin growing under adverse conditions, such as the beginning of winter or before being eaten by a hungry critter. A delicate combination of environmental cues and plant hormones maintain – and break – seed dormancy. When temperature, light, moisture, and other environmental conditions are right for that seed, hormones like gibberellin (GA) and abscisic acid (ABA) will shift in balance and germination will occur. Dormancy is typically maintained when levels of ABA are higher than levels of GA, and is broken when levels of GA are higher than levels of ABA.

When germination occurs while the seed is still within or attached to tissue of the parent plant, this is considered vivipary. Appropriately, the word “vivipary” is Latin for “live birth”. Vivipary is an essential strategy for some plants, such as mangrove trees, to increase likelihood of reaching a safe place to grow. For most plants however, vivipary is considered a physiological disorder or otherwise undesirable outcome as it decreases likelihood for successful establishment and growth, post-germination. Some highly-domesticated plants, like tomatoes, peppers, strawberries, wheat, and corn, are more prone to vivipary than others.

Seed germination within an overripe tomato. Photo credit: J. Copes.

While there isn’t uniform consensus on what combination of factors trigger vivipary, promoting high ABA levels in seeds while they’re still in the parent plant will certainly lower the odds. While there is nothing that can be done to change the genetics of the tomato on your counter, you can take steps to minimize the environmental triggers that would decrease ABA levels. Minimizing free moisture, preventing excessively cool temperatures, and drying, consuming, or processing the seed before the fruit bearing it become overripe are important strategies.

For tomatoes specifically, be sure to harvest them before they are fully ripe! Overripe tomatoes are much more likely to experience vivipary. For the same reason, whether buying or growing your own vine-ripened tomatoes, it’s important to consume them quickly. Furthermore, be sure to store your tomatoes at room temperature and not in the fridge. Not only will they be more likely to have a mealy texture when you eat them, but low temperatures may also increase the likelihood of vivipary.

The next time you happen to take a bite of a tomato filled with seeds that have experienced vivipary, don’t fret! The taste and texture may not be what you were expecting, but they’re perfectly harmless. That said, a better destination for a viviparous tomato may be your garden bed rather than your caprese salad! Seeds that have germinated within the fruit will still grow and eventually produce fruit like any other tomato seedling.

If you have questions about growing tomatoes, or any other gardening topic, call the UConn Home & Garden Education Center (toll-free) at (877) 486-6271. You can also email us at ladybug@uconn.edu, visit our website, www.homegarden.cahnr.uconn.edu, or visit your local UConn Cooperative Extension center.

This article was published in the Hartford Courant May 24, 2025

All-America Selection Winners for 2025

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by Dawn Pettinelli, UConn Home & Garden Education Center

Each winter the All-America Selection winners are announced. This non-profit organization has established trial gardens throughout the United States and even as far north as Canada. New varieties, species or strains of annuals, vegetables and bedding plants are grown and judged on their performance. Those chosen as winners are outstanding plants and deserve a trial in your gardens as well.

This year’s national winners include 3 vegetables and 5 flowers. ‘Green Lightening’ is a very attractive, striped pattypan squash that tastes as good as it looks. The 5-inch or so fruits weigh in at 1 to 2 pounds and are ready to pick about 50 days after planting from seed. Judges marveled at the abundant yields on these 2 feet high, bushy plants.

Kohlrabi 'Konstance'
Kohlrabi ‘Konstance’ Image by all-americaselections.org

Kohlrabi ‘Konstance’ exudes a vibrant purple color as well as a sweet, crunchy texture. A curious but easy to grow and tasty addition to the vegetable garden, this kohlrabi matures at just 42 days from seed. Upright plants, about a foot high, produce round, purple 4 to 5-inch ‘bulbs’ that can be eaten fresh or served roasted or sauteed. Fruits are crack-resistant and plants resistant to several diseases.

Sweet pepper ‘Pick-N-Pop Yellow’ produces adorable, snack-size, extra sweet mini peppers. The pointed, conical fruits are about 4 inches long springing from compact 2-foot-tall plants. The prolific harvest begins about 65 days after transplanting. This variety shows great resistance to bacterial leaf spot.

One can never have too many dahlias and this year’s AAS winner, ‘Black Forest Ruby’ is a gem that can be started from seed. Since this variety is an octoploid (having 8 times the normal chromosome number) there is much variability in flower shape (ranging from single to double), plant height and structure. Most will be upright about 2 feet high with jet black foliage and ruby-red flowers. You can save tubers from the best-looking plants.

Dianthus ‘Interspecific Capitan™ Magnifica’ with its impressive bicolor pink and white frilly blooms looks as good in the garden as it does in a vase. Plus, the more you cut, the more blooms appear. Summer heat tolerance was impressive with the 2-inch flower heads also standing up to rain and cold. Plants range from 1 to 1 ½ feet tall and bloom all summer. Look for these vegetatively propagated plants at your local garden center.

Sunny sites will positively shimmy when planted with marigold Mango Tango. This rich red and primrose yellow bicolor blooms all summer long even without deadheading. Reaching only 8 to 10 inches in height makes it perfect for edging garden beds, containers or window boxes. Seeds can be started indoors and plants set out after the danger of frost has passed. Fertilize and water regularly for bountiful blooms.

Can there be too many petunias? ‘Petunia Shake™ Raspberry’ will convince you that there’s always room for one more. The fantastic flowers are reminiscent of a blended raspberry milkshake swirled with lemon-lime green sorbet. The 5 to 8 inch mounded plants can do front of the border duty, serve as groundcovers or billow over hanging baskets. Plants will bloom about 70 days from seed and hold up to heat and rain.

Snapdragon Double Shot Yellow-Red-Heart
Snapdragon‘DoubleShot™ Yellow Red Heart’Image by all-americaselections.org

I’ve never thought of snapdragons as fragrant, yet ‘DoubleShot™ Yellow Red Heart’ is said to have an amazing candy-like scent. Aside from this unusual trait, Yellow Red Heart promises to delight with vibrant yellow blossoms with a red throat that start early and continue through to a heavy frost. This snapdragon reaches about 20 inches in height with semi-double 1 to 1 ½ inch blooms produces all season long and able to tolerate light frosts.

Four regional 2025 Ornamental Winners well suited to the Northeast, include one petunia and 3 nasturtiums. If you’re looking for a vibrant pink petunia great for bedding and containers, try ‘Dekko™ Maxx™ Pink’. The vibrant pink 1 to 1 ½ inch starry blooms are produced all season long and hold up well to rain and heat.

Nasturtiums are top performers in garden beds and containers and are noted for their hummingbird attraction and edible leaves and flowers. New colors in the Baby series of nasturtiums to try out this year might be ‘Baby Gold’, ‘Baby Red’ and ‘Baby Yellow’. All can be grown from seed and start blooming about 50 days after sowing. Two-inch blooms cover compact 12-inch-high mounded plants. Colors are intense and plants stand up to drought, heat, cold, rain and wind. Considering our fluctuating summer weather, these are sure to do well both in the garden and in containers.

Check out these and past AAS winners. They were chosen because of their remarkable characteristics and they are sure to be winners in your yard too.

For your gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension center.