Monroe County Master Gardener Association

It isn’t easy keeping a garden going in mid summer.  With no measurable rain to speak of, my  plants and lawns  really took a beating this year.  The only time I broke out the hose, was to do some deep watering on an as needed basis. But my garden was far from being on life support.   Plants do have a natural way of coping with these adverse conditions if you let them.  There is a surprising amount of moisture in the morning dew during mid to late summer, and the plants will tap this resource to stay alive.  I believe in deep mulching in order to conserve soil moisture and this has enabled me to keep a garden on a sand hill.

Drought stressed lawn on sandy ground leach bed

I have lived in some very arid areas and didn’t grow up with the tradition of a season long  green  lawn and bountiful annuals.  My landscapes in California were always drought resistant shrubs and shade trees.   The color came from borders of hardy gazanias, portulacas, vincas and other sun loving plants.  I am not suggesting xeriscape unless you want to do a variation of a southwest garden…but a little commonsense and an understanding of plant physiology will get you through these trying dry spells.

•  TURF GRASS:   This is probably the most visible area of drought stress. You should ask yourself just how important it is to maintain that spring green, or you can become accepting of the summer stress and live with a brown lawn. The grass is not dead, but merely in a survival dormancy mode until the cooler temperatures and the regular rainfall pattern resumes.

Drought stressed lawn

Grasses need about 3/4 of an inch of water every three weeks to stay alive while dormant. You should try to avoid any heavy traffic over it while in this fragile state, or you will kill the grass.  Dr. Dean Krauskopf recommends applying the water ration in one application.  He cautions against random light sprinklings, as this will just cause the grass to break dormancy.  Unless you are prepared to water heavily from then on, the grass will be damaged if not killed.  Of course it helps to have planted the tall fescue type of grass and to have the mower set to at least 3″ high when coming into summer…and maintaining a good soil fertility.

• VEGGIE GARDEN:  Here your method of growing will have the most effect on how you conserve moisture.  I have had a lot of success growing veggies in straw or a compost/straw mix for a variety of reasons.  I would recommend growing your veggies in some form of a heavily mulched bed, using a drip system for watering rather than overhead watering from a hose.  Not only will you avoid a lot of pathogen problems, but you will promote better root development by this method…and it will save you time and money by using less water.

Straw mulch and drip system

Tomato with mulch

Also pay attention to the particular growth stage of your plants.  For example, sweet corn that is in the ear filling (reproductive) stage will require extra water than when in the vegetative or leaf mode…if you want to harvest full juicy ears. The same applies for your root veggies, squashes and melons.

• TOMATOES:   By far the most popular of our warm season vegetables, even these sun lovers can take a sudden turn for the worse in extremely hot weather. Tomatoes require daily watering if they are to be productive.  With a hose this should be in mid morning, taking care to avoid splashing wet soil onto the plants.

Tomato with blossom end rot

But be prepared for an interruption of fruit production when the average daytime temperatures are over 90 deg and the nighttime ones are over 70 deg. These plants will go into survival mode and do not set fruit as they attempt to control their sugar output.  Plant physiology once again is trying to weather the dry spell.

This is also true of the other solanaceous family relatives, the eggplant, pepper and potatoes…and even the distant relative, our showy petunia. Tomatoes need regular watering if they are already producing fruit to facilitate calcium uptake and avoid the common blossom end rot.  Take care not to overwater if the plants are coming out of drought stress, as you will leach out valuable nutrients including the all important calcium.  You can read more about this in some of MSUE’s vegetable tip sheets…just follow the resources links found in the blog index.

• ANNUALS, POTS, HANGING BASKETS:   These are obviously the most vulnerable to heat stress.  Annual beds should be mulched to conserve moisture and watered frequently.  Pots and hanging baskets should be temporarily relocated to a less sunny position, preferably away from drying winds.  They should be watered at least twice daily if the containers are small.

Repotted drought damaged potted petunias

Also your choice of potting soil will play a big part in the overall well being of your container plants.  I gently try to repot or renew some of the light potting mix the nurseries use to grow the plant, with compost.  This medium  has superior water retention properties over its peat based cousins, as well as a good shot of valuable nutrients. I would not recommend using any foliar fertilizer during periods of extreme drought stress to avoid burning the foliage.  With pots I have found it better to use a quality pelletized fertilizer at planting to promote good root development, which will help the plant survive the summer heat.  Frequent applications of high nitrogen formulations will result in excessive leaf growth and impressive flowers, but at the cost of  increased watering during hot spells.

• TREES AND SHRUBS:   Generally these will weather long dry spells as their root systems are larger and usually more developed.  This makes them able to more easily access the subsurface moisture that the more shallow rooted smaller plants cannot. The exceptions are of course, fresh transplants and young stock, which will require at least twice weekly watering or as needed during a prolonged dry spell.

Dehydrated evergreen

Drought stressed pine needles

Arborvitae with drought stress

Conifers, particularly arborvitae,  are susceptible to tip burn and browning in hot dry spells.  In this area, this is becoming quite prevalent as we are now in our second year of drought-like conditions.  Often these trees went into winter dormancy without adequate hydration and suffered some winter desiccation damage.  What you are seeing now is often the result of this cumulative drought damage.  It is very important to ensure these trees are well watered before going into winter dormancy.

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As you can see much of this is just plain commonsense.  But it is often good to understand what makes your garden grow to avoid any of these problems. There is a wealth of information available online from reputable university extension sources to help you diagnose almost any problem in the garden.

Our blog has links to some from MSUE and a favorite Cornell site for veggie problems.  And of course you can always come and visit our office demo garden and see how we cope with an extremely dry spot year long, without sacrificing the variety of plantings of perennials or shrubs.

Frank Deutsch

Master Gardener 2010

Photographs courtesy of Jennie Stanger, except patio pot (mine) and blossom end rot tomato (MSUE)

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