Watering wisely

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An exuberant summer border should not require any watering once it’s established–if the plants were sited correctly in the first place. These plants are all perennials. This border is never watered or fertilized.

All horticulturists know that the main reason that plants die is improper watering. I see examples of this all the time, both insufficient watering and overwatering, and in this post I’ll explain some ways you can avoid it. But please refer, first of all to the watering guidelines page, which sets out general principles and explains the concept of “establishment.”

The first step is to pick the right plant for your site. If you place a wetland plant in a dry site, you may have to water it pretty much forever (although some wetland plants do quite well in dry sites, once properly established). A bigger problem is the opposite one: placing a plant adapted to dry conditions in a wet site, or in a site that’s watered continually. The plant is quite likely to rot away.

Many people start gardening by planting annuals, and when they go on to perennials, grasses, and shrubs, treat them like annuals. Annuals are plants that live for a single season. They include all vegetables and many ornamentals such as impatiens and marigolds. Because of their short lifespans, they do not develop large, deep root systems, so they do need continual shallow watering. (This is a big reason that I discourage clients from using annuals as ornamentals–growing them is just not sustainable.)

Most ornamentals, certainly almost all native ornamentals, are perennials: their lifespan ranges from several seasons to pretty much forever. These plants develop large, deep root systems. They put down roots that can mine the soil over a large area for minerals and moisture. To encourage them to develop these deep root systems, water infrequently, if at all, once they are established. A little drooping on a hot afternoon will not harm them. Recent research shows that stress is good for plants: it encourages them to grow deep, strong roots.

What does this mean for the average gardener? It means the following key points:

— during establishment, perennial plants need supplemental watering during dry periods only.

— once established, properly sited perennial plants do not need supplemental water except perhaps in periods of extreme drought.

— the rule of thumb for newly planted trees is one year of supplemental watering per inch of trunk diameter. So, for example, a tree with a 2-inch diameter should receive supplemental watering during dry periods for two years.

— established lawn grasses, which are perennial, do not need supplemental water, and if treated this way, they will go dormant during hot, dry periods but green up again with cooler weather or rain

— if you cannot tolerate a dormant lawn, provide deep but infrequent watering to encourage the development of deep roots

— for annuals such as vegetables, deep watering once or twice a week is better than daily shallow watering, which can lead to rot and all kinds of fungus diseases

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Optimal watering for a vegetable garden, made up of annual plants, is deep rather than shallow watering. Monitor rainfall and water only when it’s needed.

7/14/17: In the garden this week

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A luxuriant summer border–a bit too luxuriant this year. With all the rain, I have to keep cutting plants back.

Despite all the rain and warm temperatures throughout this growing season, when I look back at photos of past years’ gardens it’s obvious that many things are blooming 10 days to two weeks later than usual. Normally Rudbeckia subtomentosa begins around July 4; right now the first flowers are  opening, as you see in the picture above.

Over 4 inches of rain this week, and still counting! (It’s raining hard as I write this.) If you have a rain garden, or a spot that might become one, it’s probably been dry for the past 3 years, but it’s most likely nice and wet now. I’m seeing more powdery mildew than in recent seasons, and if it keeps raining, ripening tomatoes may crack on the vine. But all the rain is really good for our poor forest and street trees, which have had a thirsty time recently.

When it stops raining, here are some things you might do in the garden this week:

water new plantings: NOT! Rainfall for the week is well over 4 inches, so nothing should need watering. BUT keep monitoring: perennials and woody plants that you planted this spring or last fall need supplemental water during dry periods. The rule of thumb is at least an inch of water per week for newly installed plants. In dry weeks throughout the growing season (weeks with less than an inch of rainfall), you need to water all plants installed this spring or last fall. How do you know when we’ve received an inch of rain? You can make a highly sophisticated rain gauge–an old plastic container or tin can placed among the plants. I total the weekly rainfall and decide whether to water my new trees or my clients’ new plantings each week.

— all vegetables, including tender crops like tomatoes and peppers and corn, should be planted out by now, and it’s time to remove early greens like lettuce and spinach. Water deeply during dry periods, particularly when the weather is hot, and watch carefully for pests and diseases. Removed diseased plants promptly to prevent spread. Remove the flowers from basil plants as they form, and cut down the plants to make pesto as soon as you have enough leaves for a batch.

— be sure to properly tie, stake, and prune your tomato plants. Most tomato cages are much too small: the plants outgrow them before they start to bear fruit. And unless tomato plants are properly pruned, by pinching out the suckers, they will be so bushy that they’ll be especially susceptible to fungus infections like verticillium wilt. You’ll find general guidelines for growing tomatoes here and specific watering instructions here.

—  It’s a bit late to clean up the perennial garden or to divide and replant. Once the weather turns hot, plants put their energy into top growth and blooming. I would no longer move or divide plants, but if you continue to plant, water very thoroughly and keep an eye on those new plants. They will need extra water during dry periods, as explained above.

it’s too late to fertilize your lawn or to reseed bare patches, no matter what your lawn-care service tells you. Here’s a suggestion: don’t feed at all this year. The lawn will look just fine. Or wait until around Labor Day and use one application of a slow-release organic fertilizer. Avoid pesticides, fungicides, and herbicides. Pesticides kill butterfly and firefly larvae and native ground-dwelling bees as well as “bad” insects. And garden chemicals are not so great for kids or pets either; common herbicides, in addition to killing butterfly host plants like violets, are carcinogens. Best to avoid them.

— it’s also a bad time to prune woody plants. The plants are using so much energy growing, flowering, and fruiting that they have little to spare to healing a wound. There will be short window of time later in the summer. Of course, continue to prune diseased or injured plants at any time and to remove any safety hazards, such as overeager shrub that block sidewalks or diseased trees that might fall down.

It’s supposed to stop raining sometime tomorrow! get out and enjoy the garden this week.

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Rudbeckia flowers are enchanting as they open.

Ripening fruit

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Fruits of cranberry bush viburnum, V. trilobum, are just beginning to show color. Soon they will be bright, shiny red, but the birds won’t eat them until winter.

If you’ve read this blog for a while, you’ve probably realized that I’m obsessed with fruit. I noticed today that two of the many fruiting shrubs in my garden are “in that delightful state, when farther beauty is known to be at hand, and when, while much is actually given to the sight, more yet remains for the imagination.” Jane Austen always said everything best.

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Look carefully amongst the leaves–fruits of black chokeberry, Aronia melanocarpa, turn reddish before they turn black. As soon as they’re ripe, birds will devour them.

7/7/2017: In the garden this week

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Culver’s root (Veronicastrum virginicum), beloved of pollinators, is in full bloom now.

Refer back to last week’s post for some specific suggestions; not much has changed. I can see out my window that we received at least 1 1/2 inches of rain so far today, so no need to water this week. With this much rain, you need to be vigilant about fungus diseases, so carefully prune or pinch out the suckers on tomato plants to allow for air circulation.

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Verbena stricta, or hoary vervain, is one of the strongest bloomers in my summer garden. It starts blooming in late June and continues through the summer.

6/30/17: In the garden this week

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Rudbeckias will start to bloom very soon: this is Rudbeckia subtomentosa, the earliest one in my garden. It’s a large, tough plant, and it blooms nonstop from late June through September.

As you approach this long Fourth of July weekend, filled with outdoor activities, take some time to reassess your garden: would you like to spend more time enjoying the outdoors and less time on lawn care? would you like to see more birds and butterflies? Do you see fireflies? (You should, unless you poison them with lawn chemicals and insecticides.) Do your plants attract pollinators? (They should, unless they are sterile hybrids.) How could your outdoor environment be more sustainable and environmentally friendly?

Here are some additional seasonal tasks you might address during this long hoiday weekend:

water new plantings: We received almost no rain in the past week, so perennials and woody plants that you planted this spring or last fall need supplemental water: at least an inch of water, not just a little sprinkle. In addition, if you are still planting despite the hot weather, be sure to water well after planting to settle the new plants in the ground. In dry weeks throughout the growing season (weeks with less than an inch of rainfall), you need to water all plants installed this spring or last fall. How do you know when we’ve received an inch of rain? You can make a highly sophisticated rain gauge–an old plastic container or tin can placed among the plants. I total the weekly rainfall and decide whether to water my new trees or my clients’ new plantings each week.

— all vegetables, including tender crops like tomatoes and peppers and corn, should be planted out by now, and it’s time to remove early greens like lettuce and spinach. Water deeply during dry periods, particularly when the weather is hot, and watch carefully for pests and diseases. Removed diseased plants promptly to prevent spread. Remove the flowers from basil plants as they form, and cut down the plants to make pesto as soon as you have enough leaves for a batch. If you don’t grow basil, it’s not too late to buy a flat and plant it out this season.

— be sure to properly tie, stake, and prune your tomato plants. Most tomato cages are much too small: the plants outgrow them before they start to bear fruit. And unless tomato plants are properly pruned, by pinching out the suckers, they will be so bushy that they’ll be especially susceptible to fungus infections like verticillium wilt. You’ll find general guidelines for growing tomatoes here and specific watering instructions here.

—  It’s a bit late to clean up the perennial garden or to divide and replant. Once the weather turns hot, plants put their energy into top growth and blooming. I would no longer move or divide plants, but if you continue to plant, water very thoroughly and keep an eye on those new plants. They will need extra water.

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Monarda didyma, the red species, doesn’t do as well in my garden as the more familiar pink/lavender Monarda fistulosa. This year it’s quite lovely, and both are excellent pollinator plants.

it’s too late to fertilize your lawn or to reseed bare patches, no matter what your lawn-care service tells you. Here’s a suggestion: don’t feed at all this year. The lawn will look just fine. Or wait until around Labor Day and use one application of a slow-release organic fertilizer. Avoid pesticides, fungicides, and herbicides. Pesticides kill butterfly and firefly larvae and native ground-dwelling bees as well as “bad” insects. And garden chemicals are not so great for kids or pets either; common herbicides, in addition to killing butterfly host plants like violets, are carcinogens. Best to avoid them.

— it’s also a bad time to prune woody plants. The plants are using so much energy growing, flowering, and fruiting that they have little to spare to healing a wound. There will be short window of time later in the summer. Of course, continue to prune diseased or injured plants at any time and to remove any safety hazards, such as overeager shrub that block sidewalks or diseased trees that might fall down.

Enjoy the garden and the fireflies!

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A view of one of the pernnial beds taken this morning.

 

 

6/23/17: In the garden this week

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June is bustin’ out (couldn’t resist) in a perennial bed glorious with yellow sundrops (Oenothera fruticosa), orange butterfly weed (Asclepias tuberosa), and bergamot/beebalm (Monarda fistulosa), plus grasses and numerous species that have finished blooming or not yet bloomed. This border gets full sun and was originally planted over 20 years ago. The soil, which is very sandy, has never been amended in any way.

During the past few years of drought, I had forgotten what a gardening season with normal rainfall looks like. I had forgotten how the plants grow so exuberantly that I have to keep cutting them back along paths, in front of patio chairs, near the air conditioner, how quickly tomato plants grow (more on that below). And what it’s like not to have to exhort clients to keep newly-installed plants well watered until they’re established. It’s a pleasant change.

As I write this, the predicted rain has just started. Can I confess that given a choice between a dry weekend and a good soaking rain, I’d vote for the rain in most cases? But the thing about gardening is that we don’t get a choice.

Here are some things you might consider in your garden this week (after the rain stops, of course):

water new plantings: We received about 1 1/2 inches of rain in the past week, so no watering should be necessary this week. However, you should always water well after planting to settle the new plants in the ground. In dry weeks (those with less than an inch of rainfall), you need to water all plants installed this spring or last fall. How do you know when we’ve received an inch of rain? You can make a highly sophisticated rain gauge–an old plastic container or tin can placed among the plants. I total the weekly rainfall and decide whether to water my new trees or my clients’ new plantings each week.

— all vegetables, including tender crops like tomatoes and peppers and corn, should be planted out by now, and it will soon be time to remove early greens like lettuce and spinach. Water deeply during dry periods, particularly when the weather is hot, and watch carefully for pests and diseases. Removed diseased plants promptly to prevent spread.

— be sure to properly tie, stake and prune your tomato plants. Most tomato cages are pretty useless: the plants outgrow them before they start to bear fruit. And unless tomato plants are properly pruned, by pinching out the suckers, they will be so bushy that they’ll be especially susceptible to fungus infections like verticillium wilt. You’ll find general guidelines for growing tomatoes here and specific watering instructions here.

—  It’s a bit late to clean up the perennial garden or to divide and replant. Once the weather turns hot, plants put their energy into top growth and blooming. I would no longer move or divide plants, but if you continue to plant, water very thoroughly and keep an eye on those new plants. They will need extra water.

it’s too late to fertilize your lawn or to reseed bare patches, no matter what your lawn-care service tells you. Here’s a suggestion: don’t feed at all this year. The lawn will look just fine. Or wait until around Labor Day and use one application of a slow-release organic fertilizer. Avoid pesticides, fungicides, and herbicides. Pesticides kill butterfly and firefly larvae and native ground-dwelling bees as well as “bad” insects. And garden chemicals are not so great for kids or pets either; common herbicides, in addition to killing butterfly host plants like violets, are carcinogens. Best to avoid them.

— it’s also a bad time to prune woody plants. The plants are using so much energy growing, flowering, and fruiting that they have little to spare to healing a wound. There will be short window of time later in the summer. Of course, continue to prune diseased or injured plants at any time and to remove any safety hazards, such as overeager shrub that block sidewalks.

And don’t forget to count the fireflies! The more you see, the healthier and more sustainable your garden is.

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We moved the patio chairs forward to get out of the way of the raspberries. The elderberries (white flowers in background) are especially tall and vigorous this year.

Second flush

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Look closely at the foliage of this oak tree (swamp white oak, Quercus bicolor). Notice the small, reddish new leaves at top right and bottom left, as well as all the chewed leaves.

This is a closeup of the oak tree we planted in the front yard last year, taken today. Many trees put out a small second flush of new leaves around this time if growing conditions are good. It’s just another sign that we’re getting normal amounts of rainfall this year.

Notice as well that quite a bit of chewing has occurred on these leaves. You can see both tiny holes and marginal bites. That’s just fine. One of the reasons you choose an oak tree is that it supports more species of insect than any other tree. Insects eat plants. But in a well balanced ecosystem, with a variety of native plants, they never do serious damage. A few chewed leaves is a small price to pay for native insects and the birds that eat them.

Look closely at your garden to see if things are in balance.