We recently experienced extremely hot and humid weather, and summer had only just begun. We can expect more days like that – often called “dog days” – so let’s get ready for them.
The hottest weather is rough on people and dogs, but it also kills or damages plants. Our flower baskets, vegetable beds, or home landscapes are investments, and precious to us. And we can take steps to help them survive, thrive, or recover from tough conditions.
Let’s do some proactive gardening. I’d call it “weatherscaping.”
What can be saved
If you went away and didn’t water during a brutally hot week, or you didn’t water deeply enough, some seedlings (vegetables or flowers) or basket plants may have died. End of story. You still have time to replace many plants; see what’s in your garden center.
What’s less obvious: Woody plants (trees and shrubs) or perennials that you planted during the last couple of years may have suffered damage from drought and heat. Below ground, the little roots were searching for moisture exactly when the above-ground plant was putting out new leaves or buds. They might have been stressed enough that the roots shriveled up, and buds or leaves dropped or came out puny. Prolonged stress like that can kill a recent planting.
Here’s a typical garden center experience: The customer brings in a dead plant that he dug up to show the store manager. “You sold me this bad plant, and I watered almost every day!”
A professional can see that the roots have withered and died (even if they are momentarily wet from a watering attempt). What the customer (or nature) didn’t do well enough was to provide water to the depth of the roots in the soil. A daily surface watering did nothing. The root ball is desiccated, fatally.
You can bring many plants back, though. If you see wilting it means “Help!” Water immediately anything that is wilted. If a hanging basket plant is very wilted and dry, its soil pulling away from the pot, then sink it into a large tub of water to reabsorb moisture. This works best with high-quality potting; buy your plants from professional growers. And water new plants deeply, where the roots are.
Prepare for the worst
In the western United States, the term “xeriscaping” entered the popular gardening culture long ago and crept its way here. Smart landscape designers and gardeners advocated the use of native plants, or others that suited the existing climate. (Don’t plant a New England woodland garden in an Arizona front yard.)
These xeriscaping principles apply to all of us:
• Group plants by their water requirements. Mediterranean (lavender) or prairie plants (grasses, black-eyed Susans) or desert plants (succulents) grow on high ground and sunny places, with good drainage. Moisture-lovers (Astilbes, hydrangeas) should be in organic soil, near the hose or in-ground water system and out of baking, afternoon sun.
• Choose heat-loving and drought-tolerant plants. Portulacas, for instance, flower incessantly in hanging baskets or in dry ground, in spite of some neglect and minimal water. Many lovely flowers that you bought in May do not do that.
• Maintain a tall lawn (more than 3 inches) to preserve soil moisture, and let it rest in summer. Thick, healthy lawns grown in compost-rich soil can go brown (dormant) for weeks in summer, and then turn green when rainfall resumes.
• Grow less lawn or low-maintenance lawn: Let some areas become meadow. Replace some grass with low-maintenance perennials or native grasses. Purchase quality seed or sod that suits your soil and site.
• Deliver water to the plant roots: Use in-ground watering systems to serve important plants (especially trees) in time of need. Hand water at the base of plants when necessary.
• Add compost to new and existing lawns and gardens; compost helps retain soil moisture.
• Make the most of the water you have: Reuse household water (greywater). Water in the morning for best efficiency. Place rain barrels to capture rainfall or roof runoff.
Finally I advise what every good gardener does intuitively: Walk around the garden every day and observe: Dry, cracking soil tells you it needs compost mixed in (and then a good soaking). Soil that dries too quickly suggests you should spread mulch after a good rainfall, so moisture lasts longer. Wilting plants cry for immediate watering.
Containers in full sun may ask you to move them into some shade, and some perennials clearly ask for transplanting to better sites in the future. (Last week I even dug up a couple of stressed perennials or young shrubs that appeared to be struggling in their locations, and put them in great potting mix in pots for the season.)
And you will cut back finished flowers and stems, and pull weeds as you go along.
Heat and drought are the extreme conditions that are fresh in our minds. But remember wind storms, severe cold, and flooding?
My “weatherscaping” concept suggests steps for surviving those times too; we’ll take them on as we face them. Rain gardens, trenching, installation of drainage, wind breaks, preventive tree care and plant selection are all part of preparing for garden and landscaping health and survival.
Plan ahead, realistically. It will get very hot again out there.
Sally Cunningham is a garden writer, lecturer and consultant.