Surviving a heat wave: 6 hot weather watering tips
Garden of Eatin', How-To

Surviving a Heat Wave: 6 Hot Weather Watering Tips

This post is in partnership with Gilmour Garden and Watering. All thoughts and words are my own.

It’s here — the dog days of summer. Or should I say, it’s been here, as we’ve been feelin’ the heat for the past few weeks with seemingly no end in sight.

My Southern California garden is accustomed to the sultry weather this time of year, but it’s not any easier on the plants than it is on me. We have a full south-facing garden and September is generally the hottest month for us coastal dwellers, when Santa Ana winds blow in from the desert and bring extremely dry, hot and dusty winds that amplify an already dry season.

Keeping the garden cool and well-watered is key to helping plants survive the sweltering weather. Even with drip irrigation installed in my garden, I find that I still need to supplement with hand watering during our drought and heat spells. I keep a few sets of Gilmour’s Flexogen Super Duty Hose and Heavy Duty Thumb Control Watering Nozzle in different parts of the yard, and have been using them for the past year to water our containers and hard-to-reach corners.

Having tested all types of nozzles over the years, I’ve discovered that I really like having a thumb control. The water turns on and stays on, without me needing to squeeze a trigger — no more achy hand after a day in the garden! It’s almost life-changing when you’re someone who spends a considerable amount of time outside (and I’ve actually started replacing all my trigger squeeze nozzles with this thumb control model). I can easily adjust the water flow with my thumb as I move from plant to plant, and I’m always a fan of pattern nozzles, which offer so much more versatility than a standard spray nozzle.

Gilmour Heavy Duty Thumb Control Watering Nozzle

As for the hose, well, it’s a hose — it works, it’s relatively lightweight, and so far it’s burly enough to take some abuse in the garden. (I am definitely not one to be gentle on my gardening gear!) The thickness of the material also seems to help keep the hose from kinking. But the thing I like most about it is actually the neutral gray color and glossy coating. While this may sound superficial, the color and coating resists dirt very well — a huge plus in my book.

I have some lighter-colored hoses, and a slight annoyance with them is the fact that they seem to grab onto every speck of dirt and look really grubby pretty fast. (I use and abuse my hoses, remember?) I guess some people would prefer function over form, but putting my hands on a grimy hose deflates the fun of watering a bit (which, for me, is already more a chore than a meditation). So if a hose can stay clean and sharp-looking as well as get the job done, I’m all for it.

Gilmour Flexogen Super-Duty Hose

To help your plants switch to summer survival mode — while being mindful of our limited resources — I’ve partnered with Gilmour to bring you my top six tips for hot weather watering.

1. Time your watering for the morning or late afternoon.

The best time to water your garden is from 6 am to 10 am — before the heat of the day sets in, giving your plants plenty of time to drink up and any moisture on the leaves to dry off before nightfall. If that isn’t possible, the next best time is from 4 pm to 7 pm. Unless you live in an arid climate, try to avoid watering at night, as cool and wet conditions could encourage fungi and bacteria, slugs and snails, sow bugs, earwigs, and other pests into your garden.

But all told, don’t worry if all you can do is a midday watering — any water is better than none at all, and the oft-repeated belief that watering on a hot sunny day will damage your plants is a gardening myth that’s been debunked by science.

Leaf scorch caused by midday watering or water droplets is a gardening myth

Sunburn (which often appear as bleached areas on the foliage of young transplants, heat-sensitive plants, and distressed, underwatered plants) is caused by simple overexposure to the sun, not by water droplets that supposedly magnify the sun and scorch the leaves. There are good reasons for not watering in the middle of the day under a blazing hot sun, but leaf scorch is not one of them.

In the morning, the air and soil are cooler, which minimizes evaporation. The lack of wind means you avoid wasting water to wind drift. And most importantly, plants absorb water more readily when they’re not under heat stress — a condition that’s more likely to occur when the sun is at its peak.

2. Water well and water deeply.

Just like people, plants need thorough hydration during times of excess heat. This is especially true of outdoor container plants, as well as new plantings that haven’t yet established their roots.

Container plants — particularly those in smaller pots, clay pots, and baskets lined with coco fibers or sphagnum peat moss — are more susceptible to drying out than their in-ground counterparts. In the height of summer, these potted plants need special attention and may require watering every day or even twice a day. A good rule of thumb is to water when the first 2 inches of potting soil feels dry. The smaller your container, the more you’ll have to water it.

Water container plants more frequently than those in the ground

Both annual and perennial plants in the ground benefit from a good deep soaking up to three times a week. Allowing the water to penetrate slowly and fully into the soil (to a depth of at least 6 inches) encourages roots to grow deeper and stronger and protects them from the hot soil surface. Remember: Infrequent deep soakings are better than frequent light sprinklings.

Aim the water right where it’s needed — at the root zone of your plants — to reduce the chances of runoff and evaporation. During periods of extremely dry, hot weather, I also like to give my plants (especially the more fragile or heat-sensitive ones) a gentle overhead shower with the “garden” setting on Gilmour’s thumb control watering nozzle (a full, consistent spray similar to a soft rain).

Give your garden a gentle overhead shower when needed

From a conservation perspective, it’s not the most economical use of water, but there are times when it’s called for to promote a healthy garden. In dry, windy weather, a fine layer of dust can build up on your plants and reduce their ability to photosynthesize efficiently. Heat-stressed plants are also more prone to pests like aphids, which can naturally be controlled by a sharp blast of water (I like the “jet” setting on the nozzle for this purpose). And finally, a quick, cooling shower can offer relief to a drooping plant, as it helps lower leaf temperature and prevent heat stress.

3. Promote high humidity.

Plants that like it humid, such as ferns, ginger, hibiscus, and elephant ears, should be misted frequently during periods of dry, hot weather. The “flower” or “soft wash” settings on the nozzle are perfect for delivering a delicate, uniform spray of water to these moisture-loving plants.

Mist plants with the "flower" setting to promote high humidity

If it’s particularly breezy, you may need to mist them a couple times a day and give the garden a second watering in the late afternoon to increase humidity.

4. Shield heat-sensitive plants from excessive sun.

A heat wave is hardest on new transplants that haven’t had time to develop a strong root system (including drought-tolerant transplants, which — contrary to popular belief — still need regular watering for the first year or two while they get established).

If your plants are in containers, move them to an area of the yard that’s partially shaded in the afternoon. Transplants that need to go in the ground sooner than later should be hardened off first, then planted in the garden where they get only dappled light or afternoon shade. (Quick tip: Grow them next to taller annuals or deciduous perennials that offer some cover. By the time the new plants establish roots and require full sun, those taller plants will have died back.)

Harden off transplants and plant them in dappled or afternoon shade

Other plants in the ground can be protected by shade cloth or row cover, which still lets in light and water but blocks a specific amount of sun (called a “shade factor”) from 25 percent to 90 percent, depending on its configuration.

In a pinch, even a white (or light-colored) bed sheet strung across your garden bed or draped over your plant cages will work. The sheet lets in all the warmth and light of the day while shading your plants and reflecting light off of them at the same time.

5. Don’t fertilize during a heat wave.

Very high soil temperatures (above 85°F) can cause plants to go semi-dormant, so they use very few nutrients while they’re in survival mode and aren’t prepared to make use of them. Withhold the fertilizers (or apply a weaker diluted solution) until the weather cools off a bit and your plants have a chance to recover.

Avoid fertilizing during heat spells, or use a weaker diluted solution

When I need to give my plants a nutritional boost in high summer, I make sure the soil is evenly moist first (to reduce heat stress and improve absorption) and use a half-strength organic liquid fertilizer right at the root zone.

6. Keep as much moisture in the ground as possible.

This really should be the number-one tip, but I hope that adding it last ensures you won’t forget it! An organic mulch like shredded bark, wood chips, or straw (not hay — you don’t want to introduce all those weed seeds to your garden) conserves moisture, smothers weeds, regulates soil temperature to keep plant roots cool in summer, and adds small amounts of nutrients to the soil through decomposition. It also prevents soil (and whatever fungi and bacteria are lingering in the ground) from splashing up on the leaves while watering, which reduces the spread of disease.

Lay a thick layer mulch to conserve moisture, regulate soil temperature, and reduce the spread of disease in the garden

A minimum 2- to 3-inch layer of mulch should be added on top of the soil, taking care not to pile it up around the base of your plants (as it can hold too much moisture against the stems and lead to rotting). Replenish the mulch as needed throughout the year. During intensely hot weather, don’t be afraid to layer it on thick — up to 4 inches if needed to shade the soil from heat and sun.

Brought to you by Gilmour Garden and Watering. Thank you for supporting the brands that support Garden Betty.

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  • Aimee

    Absolutely love the bedsheet idea – we started doing that a few years ago, going down to Goodwill to pick up a few white queen/king size sheets and it works perfectly as a shadecloth over our tomatoes and bell peppers.

    However, I’d disagree strongly with watering in a heatwave from 4-7pm – at least here in Oregon, that’s the hottest part of the day and during summer, is when the direct sunlight is on the plants and the water evaporates very quickly. We prefer to water in early morning, but our alternative is 7-9pm when the sun is not directly beating down on everything.

    • The suggested times should only be used as a guideline — northern and southern climates will differ in the intensity of sunlight their garden receives throughout the day, as well as when sunset actually occurs, so everyone should exercise reasonable judgment when watering their plants.

  • Karen Fergason

    Great tips. Early this spring I planted an apple seed and have watched the young tree grow like a weed….until I left town for a weekend and it died in the desiccating winds, crisped like fall leaves. My lesson learned: make sure you have the appropriate size pot for your plant because it will suck the soil dry.

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