Watering a garden is one of those things that sound simple and really aren’t. Sure, anyone can pour a bucket of water over a plant. But when we are dealing with drought, every drop must count. Likewise, when we have a large garden and a few other responsibilities, every minute must count, as well.

So what is the best way to water a garden? Let’s find out.

First Things First: Why We Water

Why we water is simple, right? We water to keep the plants alive.

Well, yes, but actually it is a little more complicated than that.

When providing mineral nutrition, is it better to feed the plants or feed the soil? Organic gardeners will likely know the answer: Feed the soil. The soil is home to all of the beneficial biology that makes vibrant plant growth happen. It is a little bit like the principle of “give a man a fish and feed him for a day, teach a man to fish and feed him for a lifetime.” We have our choice of being directly responsible for feeding plants to keep them growing or setting up a soil-based ecosystem that can do the work for us.

Now extrapolate. Is it better to water the plants or water the soil? Water the soil. No moisture, no soil biology. Yes, we can water the plants and keep all systems running for a day, but then watering becomes a daily crisis. Or we can water the soil with a view toward optimal ecosystem functioning.

Preparing the Soil

Effective watering starts with preparing the soil to receive the water. This necessitates a porous soil structure with plenty of organic matter, which acts as a sponge. It has been estimated that every 1% increase in soil organic matter increases soil moisture retention by as much as 25,000 gallons of water per acre.

A cover crop of clover can work wonders in producing this type of ideal soil. Once the cover crop is terminated, all that remains to be done is deep aeration, as with a broadfork.

What to Water When

Next comes the question of what to water and when. Typical recommendations involve keeping the soil surface moist for fresh seeds and transplants, then a deep weekly or twice weekly watering for established vegetables, delivered directly to the roots.

These methods often promise great efficiency and little water waste—if the goal is to water the plants. But if the objective is to water the soil and thus facilitate the soil ecosystem, the soil starts out too wet at seed time and ends up largely too dry except right at the base of the plant the rest of the time.

If we have prepared the soil, we are actually well on our way to watering very little at all. Surprisingly, many vegetables, especially heirlooms, will thrive on no more than your natural rainfall—provided this crucial step of soil preparation has been undertaken. How can this be? The combination of porous soil structure and ample organic matter enables excess moisture to run off and the proper quota to be retained and slowly released to microorganisms and plant roots alike as needed. As a result, plants stay healthy and deliver luscious produce, rich in nutrients because the soil mineral content has not been diluted through overwatering.

Healthy soil will enable you to take a largely hands-off approach to watering. However, there are slight differences for each stage of plant growth.

Seeds

Seeds can actually be started without supplemental watering or even presoaking. In most cases the keys are very simple:

• Choose the right time. Starting seeds during an extended dry spell is difficult. Usually, the best time to plant is the day before a rainfall. But even if you miss your guess, do not panic. The seeds can safely sit in the ground for a few days without rain. (Cash crop farmers plant this way all the time, right?) In fact, allowing the seeds to choose their own timing for germination will actually provide them with optimal temperature and moisture conditions for growth.
• Firm the seed bed. Do not compact the soil, as this will destroy the desired porous structure. However, firmly patting the bed after working the soil will ensure enough contact between soil particles to establish adequate capillary action to bring up moisture as necessary, and it will also help ensure that the seed makes contact with the soil. (Note that the front wheel on some precision seeder models are designed to act in this way.)
• Cover the seeds. A light covering of loose soil on top will protect the seeds from direct sunlight and evaporation.

Note that seeds started in raised beds and other containers will be trickier, as these elevated beds tend to be hotter and more evaporation-prone than a bed in the ground. A light sprinkling of straw mulch may be a necessary step to ensure germination.

Transplants

A hands-off approach does not work so well when it comes to transplanted seedlings, as they have been artificially raised in a sheltered environment and rudely moved to the real world. A good soaking immediately after transplanting is necessary for their survival, and it will also help settle the disturbed soil around the roots. Also, a daily followup may be required for at least a week, depending on the weather.

Established Plants

Established vegetables can often thrive on no more than the naturally occurring rainfall, as long as the soil is healthy. You will only have to watch out for the following exceptions:

• Extended dry periods. If no rain has fallen in three to four weeks, action may be required. Any time the rain stops for more than two weeks or so, monitor the plants to get a feel for how soil moisture levels are doing.
• Raised beds and containers. Raised beds and containers get hot, and they evaporate moisture quickly. They will require regular intervention.
• Soil containing excess nutrients or salts. A good dousing can correct this situation easily.

The Water Source

Now that you know what and when to water, you will need a suitable source for watering.

The best source of water to use on garden plants is the same source that they would naturally use—rain. Stored rainwater is naturally soft and often contains small amounts of nutrients, particularly nitrogen, absorbed from the air as the drops fall.

Groundwater, on the other hand, tends to be hard. That is, it contains high levels of calcium and other minerals absorbed from underground rocks. Although watering with hard water once or twice will not harm your plants, over time the calcium from the water will build up in the soil to levels that are toxic to plants.

Even worse is city water, which usually contains chlorine, fluoride, and other toxic chemicals. This source is best avoided altogether.

The Delivery

When delivering water to a garden, a quick spray over the surface of the ground does very little other than foster fungus and encourage shallow root growth that will dry out quickly. The goal is to mimic a good soaking rain, delivering about an inch of water to ensure that moisture penetrates deep into the soil.

This promptly eliminates several common methods of watering. Sprinklers primarily water the surface (besides losing a great deal of water to evaporation), as do soaker hoses and rapid passes with a spray nozzle.

With this in mind, there are two methods that have proven themselves to be effective for watering:

• 5-gallon bucket. For larger, widely spaced plants and trees, deliver 5 gallons of water right to base of the plant.
• Spray nozzle and rain gauge. For closely spaced plants (lettuce, spinach, etc.) where individual watering is not practical, spray over the entire surface of the bed in even passes until a rain gauge placed in the center of the bed registers 1 inch.

These methods are more time-consuming and hands-on than simply setting a timer and walking away. However, they are effective for surprisingly large areas, and you will spend less time watering overall because you will be watering effectively. A reserve supply of water will be maintained in the soil, and the plants will develop deep, healthy root systems to reach it.

A Final Note on Plant Varieties

But what if, despite having healthy soil and using these watering methods, you have a few plants that fail to thrive? The answer is to let them go.

Nearly any reasonably healthy plant growing in reasonably healthy soil can and will thrive using the system described above (again, keeping in mind the limitations of containers and raised beds). A plant that does not thrive is likely defective and will create no end of headache for you in the future.

In some cases, a particular variety will fail to thrive. In this case, the variety is simply not suited to your environment and is better left alone. Many of the modern vegetable hybrids are developed for heavily irrigated commercial systems. They cannot necessarily thrive without a great deal of management and inputs.

For a more natural garden, one that will thrive in its location without considerable effort, older varieties are typically more effective. Traditional vegetable varieties were expected to produce without complex irrigation systems, and they can continue to do so today.

The benefit will be healthy, pest-resistant plants that produce a bumper crop of delicious produce, even under adverse conditions.