Heat Stress

August is supposed to be the month of non-stop tomatoes. Occasionally things go awry to interrupt those carefully laid spring visions of bountiful harvests, sauce making, and endless tomato sandwiches. Blossom end rot can appear to put an end to the crop production by damaging the ripening and developing fruits. We are seeing and receiving calls in a  higher number than more recent years from backyard gardeners complaining about black rotten spots on the bottom of their tomatoes. The spots start as a thickened, leathery spot which sinks in, always on the bottom of the fruit.

Blossom end rot on tomato, ohioline.osu.edu

Blossom end rot on tomato, ohioline.osu.edu

Blossom end rot can also occur on peppers.

Blossom end rot on peppers, photo taken by client

Blossom end rot on peppers, photo taken by client

Blossom end rot is a physiological condition due to lack of calcium. Calcium is needed by plants for  proper growth in all functions of cell making, but is most important for cell walls. Without enough calcium either in the soil, or if delivery of uptake of dissolved calcium in soil water is interrupted, cell division stops in the fruit. Tomatoes are especially sensitive to a lack of calcium.

Interruptions in uptake of calcium can happen by repeated cycles of soil drying out, receiving water, then drying out again. Times of drought and hot, humid weather make the problem worse. Plants lose water through their leaves through a process called transpiration, similar to the way we sweat. They then pull up water through their roots. If there is not enough soil moisture, plants wilt. This break is water delivery also limits calcium delivery. Tomato, and to a lesser degree pepper fruits, respond by developing rot on the bottom, the end where the blossom was before the fruit started growing.

High humidity and multiple cloudy days reduces transpiration, thereby reducing water uptake. This leaves plants not able to bring up new calcium rich water to the site making new cells of the fruit. Another interruption of delivery of calcium resulting in blossom end rot. This means that even if you have enough calcium in the soil and you water the soil regularly, the plants still may not be able to move enough calcium to where it is needed to produce a fruit.

Have a soil test done to make sure soil has enough calcium and that pH levels are around 6.5 so nutrients are most readily available. Water regularly so plants receive 1 to 2 inches of water per week for optimum growth. Feel the soil around the root zone to make sure water is soaking in and reaching the roots. Humidity and cloud cover are not obstacles we can help the plant with, so monitor the fruit for rot spots and remove. There are calcium foliar sprays which claim to deliver calcium to be absorbed by the leaves for use by the plant. This won’t help after the rot has already developed, but may help deter future spots on still developing tomatoes.

-Carol Quish




I am amazed at just how often I check the sky to see what the weather will be for next while. I know some people check the weather channel or local news channels to see what the weather people are forecasting, but I look to the sky. After so many decades of turning my eyes to the skies to see what is happening overhead, the observations have taught me what ‘reading the sky’ really means.
Blue sky with not a cloud in sight foretells a beautiful day with no rain. Gray sky usually means rain. Hazy sky says hot, humid weather and possibly thunderstorms. Dark sky brings a much higher chances of precipitation. Clouds are condensation which is the process of a gas or vapor changing to a liquid, water in this case. They contain minute water droplets floating in large congregations through the atmosphere. If the temperatures are below freezing higher up, the water freezes to become snow or sleet.
When clouds do appear, they can take different forms. There are four main categories of clouds:
Cumulus, which in Latin means heap. These are the big fluffy, white clouds that usually mean fair weather. These are the lowest clouds floating from the surface of the earth to about 6,500 feet high. If cumulus clouds grow vertically, they can turn into thunderstorm clouds.

Cumulus Cloud, by Pamm Cooper

Cumulus Cloud, by Pamm Cooper

Cirrus, means curl of hair in Latin. These are the high, wispy clouds above 18,000 feet.

Cirrus_clouds2 ed101.bu.edu
Stratus means layer in Latin. Stratus clouds are layer, appearing from the ground up to 20,000 feet. Stratus clouds make the sky look gray causing steady rain or snow fall.

Stratus Cloud, www.msstate.edu

Stratus Cloud, http://www.msstate.edu

Nimbus are rain or snow clouds in Latin.

Nimbus Cloud, ellerbruch.nmu.edu

Nimbus Cloud, ellerbruch.nmu.edu

Fog is a cloud that forms on the ground, reducing visibility and raising humidity levels.

Fog Cloud, msstate.edu

Fog Cloud, msstate.edu

And then there are the fun games you can play just watching clouds, and seeing pictures in the shapes. When is the last time you laid in grass on your back and saw a bunny in the sky?

bunny cloud, pals.iastate.edu

-Carol Quish

With the dog days upon us, getting adequate water to our gardens can be a concern. Water is essential to all life. Plants use it to transport nutrients and to maintain turgor – the cellular pressure that keeps soft tissue from wilting.  Plants absorb water (containing soluble nutrients) through their roots and ultimately release it into the atmosphere as vapor through small pores (stomata) on the undersides of leaves in a process called transpiration. Although invisible, the cumulative volume of water transpired by Earth’s plants is prodigious, producing 10% of the atmosphere’s water vapor. One large oak tree can transpire 40,000 gallons per year. Drought stress occurs as transpiration continues and soil moisture is exhausted.

Wilting muskmelon plant
Photo: Erika Saaku, Iowa State

Transpiration rates increase with:

  1. High temperatures
  2. Low humidity
  3. Wind
  4.  More soil moisture
  5. Larger, thinner leaves

Hydrangea or squash leaves wilt on hot, dry, windy days because the transpiration rate of these large-leafed plants is faster than the plant’s ability to take up available moisture from the soil.

At the other end, if a plant’s root system is compromised or undeveloped, extra care must be taken to ensure survival. The process of digging and transplanting exposes roots to the air, damaging or destroying delicate root hairs. Recovery can be difficult with the additional stress of hot weather. Provide shade and plenty of moisture to allow these essential single-cell structures to regenerate. In some cases, cutting back some of the leaf mass to reduce water requirements is advisable.  Old-fashioned advice for transplanting instructs: “water once a day for a week, once a week for a month and once a month for a year.” A very inexact guide to be sure, but a good reminder that transplants have high water demands at first and need to be weaned gradually over time.

Container-grown plants often have root systems a fraction of the size of an equivalent plant growing in the ground. Regular watering is a must, particularly when  containers are made of porous clay or fiber. Potting mixes are commercially available that contain polymer crystals which can dramatically increase the water-holding capacity of potting soils in containers.

Measuring irrigation output

“Deep and Infrequent”

This mantra of watering advice emphasizes the need to train turf grass and landscape plants to develop deep root systems in search for water. Shallow, frequent watering encourages the growth of roots close to the soil surface, making the plant vulnerable to drought stress.  Shrubs and trees with weak, superficial root systems are also more likely to topple over in a windstorm.

Root growth of turf ceases at soil temperatures of about 70°, so lawns should be encouraged to develop deep root systems during the cool weather of spring and fall. Summer watering of lawns is triage; keeping the patient stable until temperatures drop. Overwatering results in excessive growth and increased risk of fungal disease, while wasting water and fertilizers that can potentially contaminate waterways.

Mulch conserves soil moisture as it suppresses weeds and dresses up the garden.  Organic mulches mimic the natural duff on the forest floor, creating a hospitable environment for microbes, fungi, insects and worms as they perform their function of decomposing organic matter and releasing nutrients.

Managing water in the garden is a skill that gets honed over time, as the gardener develops sharper instincts for plant requirements. Water is also a surprisingly efficient and environmentally sound way of ridding plants of some insect pests such as aphids and spider mites – simply knock them off with a forceful spray from the hose. Regular flooding will discourage ground-dwelling bees and wasps (yellow jackets) from nesting in inconvenient areas.

Water makes the garden more pleasurable for people and animals alike. Bird baths, gurgling fountains, lawn sprinklers for children or ponds with fish and frogs create a richer environment and a cool oasis of refreshment on a hot summer’s day.

Children swinging in sprinkler, 1964
Photo: Museum of History & Industry, Seattle

J. McInnis

C. Quish photo
C.Quish photo
C.Quish photo

On a recent trip to Florida, I visited Hydro Harvest Farms, a hydroponic farm in the town of Ruskin. The barren lot was not the most fertile soil for growing, so the owner invested in vertical planters stacked four high. The growing medium is a soilless mix of perlite and vermiculite. The containers themselves are made of two-inch thick styrofoam, providing insulation to the roots from the heat and occasional cold nights during the winter. Mind a ‘cold’ night in mid-Florida is 35 degrees F. The plants are watered with a nutrient solution providing all the water and minerals the plants need to produce the fruits and vegetables. The solution is delivered through a series of plastic and rubber hoses and sophisticated injection pump system. Pests are controlled using IPM, integrated pest management. Pest insects are indentified, damage evaluated and only then a predator insect will be released to eat the pest insects. Crops grown are a root crops in the base rectangular planter or stand alone box. Potatoes, onion, beets and turnips were on display during this March. Herbs, different lettuce and collard greens filled the stacked star-shaped planters. And there were rows and rows of stacks containing strawberries. This area of Florida is known for its tomatoes and strawberries.  Tomatoes were already harvested and passed and the strawberry crop was just coming in.  Thankfully, my husband doesn’t mind indulging my lust for visiting farms, gardens and botanical adventures, even when we are on vacation.

C. Quish photo

C. Quish photo

Weather extremes are  being experienced here in New England during this crazy month of May. April brought a heat wave pushing plants far ahead of schedule, forcing tender new growth to develop and then on the 11th of May we had cold snap and frost. Many buds were killed as well as new leaves damaged by the frost. Japanese maples and hydrangeas were particularly hard hit. The damage at first just appears as wilted foliage, but as the days pass, those leaves  develop white areas then turn crispy brown before they drop. Some plants are only damaged on the top while others are completely defoliating. The good news is, if you leave the plants alone they will produce new leaves in a few weeks. Keep plants well watered to help the re-leafing process.

Last night’s rain and thunderstorms should have cleaned the air of those white fuzzy things floating everywhere. They are seeds of the Poplar or Cottonwood tree, Populus deltoides.

Populus deltoides

This week brought record heat of 99 degrees F! Cool weather loving plants like radish, pansy, spinach and early lettuce will bolt to the seed stage or melt away in this type of heat. Warm season crops will love the ground warming weather but may not have developed a strong root system to deliver enough water to transpiring leaves emitting moisture. The result of giving off too much moisture from the leaves faster than the roots can replace it is shown by wilting. Provide new transplants with shade  and plenty of water. Mulch the soil to keep it cool, trapping in moisture.  Tomatoes, peppers and other warm season crops can be planted into the garden now without the danger of frost, I hope!

Speaking of vegetables brings hopes of bountiful gardens and large harvests, usually more than one household can consume. Think about donating some of your excess fruits and vegetables to organizations that typically do not receive or have access to farm fresh produce. One way is through Ample Harvest, a program to do just that, started by Gary Oppenheimer, founder of AmpleHarvest.org. He is a Master Gardener from New Jersey who grew this idea in one year into a nationwide success.   Their philosophy is simply stated below.

“A nationwide effort to educate, encourage and enable gardeners with extra produce to easily donate to a local food pantry. AmpleHarvest.org gives food pantries the opportunity to be listed in a central nationwide directory so that gardeners can share their fresh produce and, garden-by-garden, help diminish hunger in America.”

Gary has requested we pass on the information to backyard gardeners everywhere.

I would very much appreciate it if you would help AmpleHarvest.org by:

  1. Letting your network of friends/family around the country know about it (just send them to www.AmpleHarvest.org – the home page explains it all), and ask that any who know of a food pantry in their community urge it to register at AmpleHarvest.org.  Although nearly 2,000 food pantries spread across all 50 states already participate, many more can and should be taking advantage of it
  2. Letting your gardening friends around the country know that when they harvest their fruit & veggies, they can donate the excess garden produce to a local food pantry… and they can find one at www.AmpleHarvest.org
  3. If you know of companies/organizations/foundations that fund anti-hunger efforts, please let me know.  Operating AmpleHarvest.org on the national scale that it has achieved requires funding and we’ve started our outreach.   The good news is that given the design of the AmpleHarvest.org Campaign, it generates a huge bang for the buck – something donor organizations appreciate.