Everyone loves the summer, but it is even more special for a gardener as we get to grow the plants we love! Times of excessive heat like we are experiencing now can make things very difficult not only for the gardener, but also for the plants. Although intense heat is detrimental to many of our crops, excessive heat early in the season can make it particularly hard to start a garden.

ML 21 Sprinkler

During heat waves, watering regularly becomes much more important. Photo by mrl2021

At this time of year, most plants do not have a very well-established root system. Many people do not plant their gardens until after Memorial Day here in Connecticut, even though mid-May is generally the last frost free day. Newly transplanted plants cannot handle intense heat – even if you are watering them. They simply do not have the established root system needed and wilt in the hot sun. The top layers of soil dry out rather quickly, and deeper roots are necessary to find the moisture. 

Seed starting can be particularly problematic at this time as well. Remember that seeds need not only proper temperature, but proper moisture. Seeds are generally planted within the first few inches of soil at most. This layer dries out rather quickly, so keeping the seed bed consistently moist during germination is a daunting task. With both transplants and seed starting, I will generally wait until after a heatwave has passed.

There are a number of crops that do not do well in hot summer heat. Most of the Brassicas despise the heat. These crops include cabbage, Brussel sprouts, broccoli, kale, etc. Peas and lettuce also do not like the heat. The best thing to do is keep these plants watered (more on this below), or planted in partial shade. Another option is placing a shade cloth over these plants to reduce the sun and lower the temperature. Some light does pass through, but they are not out in the intense sun.

Some garden victims are our planters, flower pots, and hanging baskets. Any type of container generally dries out rather quickly. They are above ground and many times dark colored. Both contribute to rapid drying out of the soil inside. Sometimes you can buy special soil or add components to the soil to prevent this rapid dry out, but you can expect to give more watering attention to containers during heat waves. Once a day watering may be necessary, though time consuming. Many of the commercial nurseries have automatic watering systems to take care of their stock while it waits to be sold. Containers should be watered until you see water flowing out the bottom. Be careful as severely dried pots will have soil pulled away from the sides and water will flow out the bottom immediately. In this case, a slow hose drip for an extended period of time may help, as will additional soil added to the pot.

ML 6-21 Flower pot

Containers of all kinds are particularly prone to drying out. Photo by mrl2021.

Although we normally think of it as a weed preventer, one of the easiest ways to prevent our soil from drying out is a good layer of mulch. You will need to put on a decent layer because a thin little layer does not do much. I put on at least three inches of mulch or more. People wonder what type of mulch is best, but I say use what you have available. Mulched areas tend to need to be watered less due to the moisture retention so make sure to take this into account when you are watering.

ML 21 Rhubarb

A well-m.ulched rhubarb plant. Photo by mrl2021

Regular water in is essential to keep our crops in good shape. This can be harder to do than you think. One trap I have been caught in in the past was believing the weather forecast. I remember one year where we were supposed to get significant rain each day. I thought, “Why water when it is going to rain?”  Well it did not. The next day it was the same story, and this went on for almost a week. My poor plants were wilting and miserable by this time. It is not good to stress the plants like this. And if you are not paying enough attention, it can be too late to fix! My rule is to water when the plants need it regardless of the forecast (unless 100% rain is predicted). Our plants need about one inch of water per week. Too much can contribute to rot and fungal diseases. Too little and our plants will languish. You can measure the amount of water being put down with a good rain gauge.

ML 21 Rain gauge

One of author’s rain gauges. Photo by mrl2021.

It is best to water in the morning. Evening watering keeps the plants wet and can invite fungal problems, and slugs love the moisture! Watering in the hot mid-day sun can cause water droplets to form on our plants and burn them when the sun’s rays hit. I have found this is particularly problematic with cabbage. In the early morning, before the heat of day, is best. The problem is that many of us go to work at that time! I set the hoses up the night before and then turn on the spigot when I wake up, and turn off before I leave. Another option is using a timer. There are many manual and digital timers out there. I generally get a bit nervous with these as your water must remain “on” for them to work. Should something fail, water will be gushing all over until you come home. I do know many people who use and like them, so I guess I am just being paranoid. 

I am going take this time to remind everyone to get a good soil test. Not only will you be able to dial in your nutrient requirements, but you should be able to find out what type of soil you have.  You will need to adjust your watering based on your soil type. Sandy soils will tend to dry out much quicker than any other type. Clay soils tend to hold water and can become water logged.  Adding humus will improve the quality of both soils.  

My last bit of advice is to not forget about you! Drink water throughout the day when it is hot.  Too many times I have come in feeling great about the work that was done, but not feeling very good physically as I did not drink enough. It is easy to focus on the work and forget about ourselves. Take frequent breaks! Try to minimize the time spent outside at the hottest part of the day (afternoon around 2pm). Try and follow the shade and work on that part of your garden if possible. The early morning and the late evening are generally much cooler, although you won’t have as much time. Wear sunscreen and/or protective hats and clothing. Above all, find a nice comfortable chair placed in the shade and in view of a beautiful flower garden. Add a cup of lemonade or iced tea and you are all set! 

Matt Lisy