Watering

Let me be candid here: I have a prejudice against watering. I think water should, in general, remain in the lakes and rivers, where it is needed by the fish and other water-living creatures. In many parts of the country we are rapidly draining groundwater and aquifers that took thousands of years to fill up. Water is essential to life, and I will surprised if we don’t see significant water crises in the United States and around the planet in the next twenty years. Even in rainy New England, we shouldn’t use water unless we need it.

I also find watering a garden boring. I don’t like standing there with a hose, or lugging hoses around from place to place.

On the other hand, water is indeed essential to life. If I were never willing to water my garden I’d be rather limited in what I could grow. So here are some tips for using water wisely and well.

Water Only Babies

Seedlings and transplants genuinely need water. If they dry out before they get settled, they will either die or be stunted. Since I’m not willing or able to schedule my garden time entirely in tune with the rain, I need to water babies.

How long something remains a baby depends on what it is. Trees I coddle for their first season and keep a careful eye on for two years after that. Peas get watered only until they germinate. Spring bulbs get soaked when I plant them and after that they’re on their own.

It help to pre-soak overnight any seed that is bigger than ¼ inch in diameter, since they have a harder time picking up enough water from the soil. Nasturtiums should definitely be pre-soaked. Beans appreciate it too, but peas don’t need it. Don’t pre-soak cucurbit seeds (squash & cucumbers); their taproots are really sensitive, so they are unhappy if you handle them after they start to sprout even a little tiny bit.

One exception to my “water only babies” guideline is rhododendrons and azaleas that keep their leaves. Because they don’t shed their leaves like deciduous plants, and the leaves are flat rather than thin like pine needles, they are vulnerable to dehydration in the winter. If your rhodie is less than five years old, or if we’ve had a dry summer or fall, then it’s a good idea to soak well your rhodie once in the fall, after the soil has cooled down but before it freezes. October is a good time for this. Put a hose under your rhodie, turn on a trickle of water, and leave it for 6 or 8 hours or overnight.

Think Darwinian

Roots go where the resources are. If they find water or nutrients in a certain direction, they keep growing. If they don’t, they don’t. So there’s a sort of natural selection going on within the plant itself, as roots that are well-nourished grow at the expense of those that are not.

This means you can predict or even control where the roots will grow. If you frequently water your garden a little bit, the top of the soil will remain damp, so roots will grow primarily at the top of the soil. And when a hot summer day comes along, and the top of the soil heats up, the roots will get scorched and the plant will be in trouble.

You want to encourage your plants to send roots down, where both the temperature and the water levels are less variable. Deep roots will make your plants healthier and less dependent on you – which means less work for you, and the plants are less likely to die if you go on vacation.

One way to encourage deep roots is simply to let the plants, after their babyhood, get watered by rain. If there isn’t enough rain, they may get a bit stressed, but their response will be to send roots down in search of water. Some of this is OK, but too much may lead to stunting or death.

If you pay attention, you will learn to notice when a plant is water-stressed. One clear sign is that the leaves are less full and plump when they have less water in them.

You can choose whether or not to do something about this stress. You are not, after all, obliged to keep every plant alive. And maybe that water is more needed by the fish.

If you do water your plants, water them deep and long. Your goal is to get a lot of water into the soil, deep into the soil, so the roots go deep and the water won’t all evaporate in the next day, or even the next hours.

Water the Soil, Not the Plants

Many people “water their plants” by spraying their leaves. This does the plant no good at all. Indeed, it can encourage fungal diseases if the weather is cool and encourage sunburn if the weather is hot. (Drops of water focus sunlight on a small area of the leaf, creating burn spots.) So try not to get water on leaves.

Most of the time I just carry water in a watering can, so I can direct it where I want it, but trees need more than that, so if you are planting a tree see the note in about tree irrigators.

A sprinkler can be helpful for watering newly-planted seeds in the spring or fall (lawns are best seeded in the fall), but don’t use a sprinkler on a hot day – most of the water will evaporate, and you shouldn’t be planting seeds in hot weather!

The best way to water the soil is generally to use soaker hoses, which are available in just about any hardware store nowadays. Lay them around the plants, turn on the tap, make sure the water flow is low enough that the water is soaking into the soil rather than flowing away on top of the soil, and leave it on for a few hours. If you aren’t sure how long to leave it, put a trowel into the soil when you think you might be done. It should be damp six inches down.

Then mulch your plants, if you haven’t already, so the water stays in the soil and the roots stay relatively cool.

Don’t Water a Lawn

Watering a lawn keeps the roots near the surface, where they are more likely to be injured or killed by the summer heat.

Grass is supposed to go dormant during the summer – its natural response to heat is to shut down and wait until cool weather returns. If you keep it artificially growing, by watering and fertilizing it, that can work, but it requires a significant investment of time and money on your part, and it also makes the grass more vulnerable to a heat wave. Even if you keep watering it, a water-dependent lawn may die when it’s hot, when an independent lawn would simply go dormant and bounce back later. If your town has to institute a watering ban, as happens in more towns as our water supplies get over-stretched and our weather gets more variable, your water-dependent lawn is in deep trouble.

Replacing a lawn is expensive. Especially since a young lawn is more vulnerable to dying in a heat spell, so you may have to replace it again and again.

So one of the best things you can do for your lawn is to not water it.

(Other good things for a lawn are not cutting it too short, sprinkling it with compost every now and then, and encouraging it to include clover, which fixes nitrogen and keeps the grass healthy.)

Containers Are a Different Issue

Plants in containers generally need water once a day in moderate temperatures, twice a day or more in high temperatures. If you want to grow plants in containers, you have to commit to watering them.

Shading the sides of the containers can help, as can investing in so-called self-watering containers. There are lots of options at Gardeners’ Supply Company and Lee Valley Tools.

Next page: Transplanting