Water Use and Control in the Garden

Is it starting to feel hot in your garden? 

Well trust me, if you are feeling it, your plants are too. Summer is a time of increased temperature and hence evaporation of moisture in the garden because of those higher temperatures. 

For the plants in your garden, the most important consideration in the months of higher heat is making sure the plants have the water they need, at the correct time, and are able to retain the water for as long as possible. It doesn’t hurt to know a few tips to reduce the amount of time we have to spend on watering as well. 



Read on for information on what to do to help plants manage water and help us manage time and resources. We’ll discuss the different water needs of seeds, seedlings/new plants, and established plants. We’ll also talk about when and how to water, and why, and finally what more you can do to keep water with the plants as long as possible, e.g., use mulch to reduce water evaporation.

Before we begin, remember that the most important guideline for watering is to never let the roots dry out. This rule means that how you water depends on the stage of seed/plant growth. 

Watering Seeds: When you direct seed in the garden

Water deeply when the seeds are planted, then water gently every day until germination, typically within the first two weeks. Small seeds that require light to germinate will do fine with surface water or misting. Larger seeds that are planted deeper, make sure you are watering deeply enough to keep the soil around the seeds moist, not wet, until they germinate.

Once the plants get their first set of true leaves, their roots are developed enough to water less frequently and less directly. Know that roots will seek water: you want to encourage the roots to spread and go down into the soil, so avoid frequent watering of just the surface. Newly sprouted seedlings have delicate root systems and may need more frequent watering compared to established plants. Keep a close eye on the soil moisture levels during this critical stage.

Watering New Plants: When you transplant vegetable plants into the garden

Watering newly sprouted vegetable seedlings is crucial to their growth and development. The frequency of watering will depend on several factors such as the type of vegetable, the growing medium, the environmental conditions, and the stage of growth. Before you plant, apply compost to the soil and mix it in to help distribute both air and moisture in the soil, which will aid the plant getting the water it needs when it needs it. Then when you transplant your vegetables, water enough to thoroughly wet the roots and settle the soil.  

Watering Established Plants (plants that are about one foot tall or less)

For established vegetable plants, in order to keep their roots moist, provide at least one inch per week of thorough watering, ensuring the water is totally absorbed in the soil. Watering thoroughly and less frequently will encourage the plant to develop stronger root systems than will frequent surface watering. 

Before watering, always check the soil moisture by inserting your finger into the soil up to about an inch deep. If it feels dry at this depth, it's time to water. If it still feels moist, hold off on watering. Most vegetable seedlings prefer consistently moist (damp to the touch) soil that is not waterlogged. Overwatering can lead to root rot and other issues. If you have a well-drained soil (soil which has sufficient organic matter or compost), the drainage will not let water pool around your vegetables.

Watering in the morning is preferable because it’s cooler, less water will evaporate, and it allows plants to absorb the moisture before the heat of the day. Watering in the evening can lead to prolonged wetness, which may invite fungal diseases.

Water gently below the leaves to reduce splashing and the chance of spreading soil-borne disease to the plants. Watering this way will also reduce evaporation. Mulching around the plant will reduce splashing. When you water, you will notice that after each pass of the wand around the base of the plant, the absorption time for the water to be pulled into the soil will increase. Continue watering until the soil is fully saturated and will receive no more water.

Once your garden is established, monitor your plants closely, observing how they respond to your watering routine and the weather, and adjust as needed.  

• Environmental Factors: Factors such as temperature, humidity, and sunlight can affect how quickly the soil dries out. Hot and windy conditions may necessitate more frequent watering, while cooler and more humid conditions may require less. If your vegetables are grown in containers consider:  
• Container Size: Seedlings in smaller containers are likely to dry out faster than those in larger containers or garden beds. Check the soil moisture regularly and water as needed.
• Container Type: Earthenware containers lose water much more rapidly than plastic containers. All containers should have adequate drainage at the bottom to keep water from accumulating and rotting the roots.
• Plant types: Larger plants, especially vining plants, may require more than one inch per week. Plants lose water through their leaves so the more leaves, the more water loss. For example, twelve foot tomato vines may require gallons of water per week. Just remember, don’t let the roots dry out.
• If there is rain, use a rain gauge to know how much rain you are getting between waterings. If you are getting an inch a week, you may need to water less.  

Watering Aids



• You will need an easily accessible water source and a hose to move the water to the garden area. Pick a hose that is not too heavy for you and is easily stored – it will increase the likelihood that you water when you need to.
• If you have a rain barrel, you can attach a hose or a piping system to the bottom of the rain barrel to move that water to the garden. Keep in mind that you should not use water collected from roofs for food production, though it is fine to use for non-edibles.
• A wand with an adjustable nozzle makes it easier to water under plants. Wands vary in length from 18 inches to 30 inches; longer wands make it easier to water close to the ground (under the leaves) without bending down. This watering method is effective and simple to use and needs no installation.

●       Drip irrigation systems: drip hose, or drip hose irrigation systems with line shut off valves and timers. Drip irrigation requires installation of drip hose, typically with shut off valves at the top and each line as well as timers. You can set the system to water on a schedule of your choosing, typically more frequently when plants are newer and then less frequently and for longer periods of time when plants are established. Adjust as needed, based on how moist the soil remains between waterings. For more information on using drip irrigation in your garden, see the following: 

https://web.uri.edu/safewater/protecting-water-quality-at-home/sustainable-landscaping/drip-irrigation/

or

https://extension.colostate.edu/topic-areas/yard-garden/drip-irrigation-home-gardens-4-702/

●       Self-Watering Container Gardens: these can be very effective especially when summers have very uneven or undependable natural precipitation. We recommend containers with a large reservoir and a garden separated from and sitting on top of this reservoir. A contained column of compost running from the reservoir up into the garden pulls the water out of the reservoir and into that garden. This type of garden is used in several forms in the Master Gardeners’ Vegetable Fruit Teaching Garden (visit us at 461 Wyoming Road, Newark, to see them). Self-watering container gardens are discussed in great detail with instructions on construction in the book “The Vegetable Gardener’s Container Bible”, Edward C. Smith, Storey Publishing, North Adams, MA, 2011.

Mulching for Reduced Evaporation

Water in a garden is lost in two ways—evaporation from the soil, and transpiration through the leaves of the plant. You can control the evaporation loss from the soil by mulching.

               Mulch is a material spread over the surface of your garden that creates a thin high humidity environment right next to the soil surface and decreases water evaporation from the soil and improves soil health. It maintains the moisture at the surface of the soil and upper soil layers by shading the soil and protecting it from wind drying. When using compost as mulch, it also helps to optimize moisture distribution by holding moisture in the soil until it is needed by the plants. All mulch applied in a thick enough layer to totally shade the soil surface will suppress weed growth, it reduces the use of moisture by weeds as well as the disturbance of soil and associated moisture loss, from weeding activities. Mulch also breaks the fall of rain drops, helping eliminate splashing of soil and soil diseases onto leaves, protects the soil surface from cracking, and promotes healthy microbe and earthworm activity in the upper soil layers.

The dual combination of compost used to retain and distribute moisture in the soil and mulch used to minimize evaporation from the soil surface produces a highly desired symbiotic relationship. 

Types of mulch

               Organic mulch (it comes from living things) includes compost, grass clippings, shredded leaves, straw, shredded cardboard, and shredded paper. 

There are advantages and disadvantages of each:

●       Loosely laid compost is an excellent mulch which provides added soil nutrients. However, it can get used up quickly and may require replenishing with added amounts frequently.

●       Grass clippings (which must be non-herbicided, i.e., with no weed killer applied to the grass) help provide nitrogen to the garden and help minimize evaporation at 2 inch height. At 3-4 inch height this mulch will help minimize weeds as well. 

●       Shredded Leaves are a great carbon source. They make good mulch and fertilizer.

●       Straw, if weed free and heavily chopped up, is very easy to use as a mulch and long lasting. 

●       Shredded Cardboard and Paper are also effective as mulch, but they are high in carbon so they may remove some nitrogen from the soil.

Placement of mulch



               Apply organic mulch around seedlings after weeding or thinning. Allow one inch of space between the edge of mulch and the plant stem; mulch touching the stem is avoided as it may increase rot and provide places for insects to hide. As mulch ages throughout the year, replenish to the desired height as recommended above: 1-2 inches to retain moisture, and 3-4 inches or more to suppress weeds. Using compost as mulch improves water absorption, water retention, and water distribution in the soil and provides the added benefits of low level, slow-release fertilization.

Watering is crucial in creating and maintaining a successful garden, and you can water more effectively and efficiently with these guidelines and examples.

If you would like to see some of these examples in person, or you just want to talk about gardening, please join us Thursday July 11, 2024 for the NCC Master Gardener Evening in the Garden, 6:30-8:30 pm, at 461 Wyoming Road, Newark. You can Register here for the event.

Check out our Master Gardener workshops here.