window box
A window box is not a garden planted in the ground and will most likely need more than an inch of water a week. Depending on the plants and their siting, they may even require watering more than once a day if the temperatures are too high.

The Self-Taught Gardener: Water is not love

The Self-taught Garden ruminates on the art of watering.

Even for non-gardeners, the sight of an oscillating sprinkler sending arcs of water across a lawn or border calls to mind a lifetime of summers, and reminds us that, like plants, we are all dependent on water to cool us down and to keep us hydrated in the heat of the season. And whether one is an expert in growing succulents or tropical annuals for window boxes, the first question asked from a newcomer is nervously whispered, sotto voce, “And how much should I water this?” The first lesson is that water is not cancer or a drug run, and this question should be asked fortissimo, because it is the question of a smart gardener.

The question of watering shares something with many of the questions new gardeners ask; their hope is for a definitive answer that they can apply to all plants and all situations. Their dream answer would be: water this plant once a week with two ounces of water and it will thrive. But life is not so simple. The old rule of thumb — that most established plants in a temperate environment that are planted in the ground need an inch of rain a week—is not without merit, but it does not apply to all plants, or all situations, and certainly not to plants being grown in containers where the soil tends to dry out much more quickly, let alone when it is 90 degrees outside.

oscillating sprinkler
Overhead watering is best done in the morning, so that leaves of plants have a chance to dry off before nightfall, which helps prevent foliar diseases.

Plants are not different from people, and a gardener needs to take into consideration a series of factors in determining what a plant needs in order to prosper. The general needs of the species itself can often be surmised by looking at where the plant originated, where it currently resides (is it in a small container that dries out quickly or is it planted in the ground, competing with other plants for a drink?), and what are the current conditions of that site (is it sunny and 90 degrees, or cool and cloudy with a lot of humidity slowing down the drying out of the soil that surrounds it?) These factors require something that all good gardeners possess: an ability to think and factor in what we know about a plant and its long-term needs, and an ability to observe the current moment and take it into consideration as well.

I remember once working on a television segment with Martha Stewart and the then-Director of Horticulture of Wave Hill, Scott Canning, on growing South African bulbs in containers. Cued up, with watering can in hand, Martha asked Scott how much to water the plants. Martha, a knowing gardener, undoubtedly knew that these plants come from the fynbos of South Africa, an arid area that has seasonal rains that bring these plants forward and that these plants benefit from dry spells and bouts of heavier watering to bring them along, but was deftly teaching her audience a thing or two about watering. Scott’s answer has stuck with me for a lifetime, because he had a larger lesson to teach us all, as he casually replied, “Martha, water is not love.” He was not reproaching her, but was pointing out the fallacy of watering. Most gardeners think that sprinkling their plants with water is a way of expressing their affection and care for the plants, showing their desire for the success of the plants. But just like giving someone too much to eat is not a benefit, Scott made it clear that the right answer is to wield the watering can judiciousnessly.

Amazon lilies send up flower stalks after a dry spell. Without a step back in watering, these plants will not flower.

There is an adage that the food writer Marcella Hazan shares about how it takes four people to make a salad — a judicious one with the salt, a prodigal one with the olive oil, a stingy one with the vinegar, and a patient one with the tossing. I do not know how much Marcella gardened, but her advice works in the giardino as well, and relates to watering on all fronts, along with a few other factors to take into consideration. When one waters, it is usually best to be generous and patient. Most plants prefer a thorough watering less often than a series of short shallow waterings. A thorough watering allows the plant to receive water throughout its root zone, versus just drinking in thirstily wherever water lands while other areas of the root zone go dry and suffer. Sometimes, with rootbound plants, this even involves watering twice, so the plants have time to absorb water throughout the root zone. (If a container has water running out the minute you water it, it is highly likely that the plant is rootbound and depending on its preferences, may need to be repotted. Some plants, such as agapanthus, clivia, and amazon lilies, benefit and flower more when root bound, but others are stunted by not having room to continue to grow. Again, know your plant.)

Water is not love, and some plants, such as these begonias, are better off drying out slightly between watering.

At times, it is also wise to be stingy with water. At the season when a plant enters winter dormancy or is slowing down in growth, watering often should be tapered back. (When a plant is slowing down in growth, it is often a good time to slow down on fertilizing, too.) Sitting in water, like a salad sitting in a pool of dressing, is not any better for a plant than for a salad. Too much water at the wrong moment, especially for plants like begonias, which like to get a little dry to the touch between watering, can cause fungal disease and leaf wilt. Certain plants, such as tomatoes and the aforementioned begonias, also prefer to be watered from below, as wetting of their leaves promotes disease. If these plants are to be watered with an oscillating sprinkler or rain hose, it is best to water them early in the day, so that their foliage has time to dry off before evening, helping to keep foliar disease at bay. I think of this as a parent who does not want to give a children (or oneself) too much to drink before bedtime because we want to get a full night’s rest without interruption.

Even succulents that require less watering are better off being given water less often but more fully.

Water may not be love, but it is a knowing parent, who realizes just what a plant needs and when. Being a good gardener is all about observation and response, and knowing when to have a full glass of water at the ready.

A gardener grows through observation, experimentation, and learning from the failures, triumphs, and hard work of oneself and others. In this sense, all gardeners are self-taught, while at the same time intrinsically connected to a tradition and a community that finds satisfaction through working the soil and sharing their experiences with one another. This column explores those relationships and how we learn about the world around us from plants and our fellow gardeners.