I killed a whole flower bed one July. Not slowly, not subtly. I planted a dozen petunias on a Saturday, the temperature hit 97 on Tuesday, and by Thursday they looked like they had been through a drought that lasted a month.

The flowers were fine. My watering habits were the problem. Here is what I do now.

Water deep, not often

The number one mistake is giving flowers a little splash every day. That keeps the soil surface wet, so the roots stay shallow and weak. Water deeply twice a week instead, so the water reaches the roots and they grow down where the soil stays cool.

The test: poke your finger two inches into the soil. Dry there means water. Damp there means wait a day. I check every morning with my coffee, and I stopped guessing.

Water in the morning, not the evening

Morning watering gives the leaves time to dry off during the day. Evening watering leaves plants damp overnight, which invites mildew and fungus. Early morning is the sweet spot, before the sun is strong enough to evaporate the water before it soaks in.

If you cannot do mornings, late afternoon is the backup. Just try to avoid noon, when most of the water evaporates before it helps.

Mulch is the unsung hero

A 2 to 3 inch layer of mulch around the base of plants keeps the soil cool and traps moisture. It cuts evaporation dramatically and keeps the soil temperature from spiking in the afternoon sun. Shredded bark, straw, or even grass clippings work.

I use shredded bark because it looks tidy, but any organic mulch does the job. The flowers under mulch survive the hot weeks that used to kill mine.

Shade during the worst hours

If a heatwave is coming, rig up temporary shade for the tenderest plants. An old bedsheet on stakes works fine for a few days. The goal is not full shade, just relief from the brutal afternoon sun. Take it down when the heat breaks.

Do not fertilize in a heatwave

Fertilizer pushes new growth, and new growth needs more water. In extreme heat, skip the fertilizer. Let the plants coast. Feeding them during a heatwave is like asking a tired runner to sprint.

Pick the right plants

Some flowers shrug at 100 degrees, and some melt. If you are planting in summer, choose heat tolerant varieties: zinnias, marigolds, lantana, and portulaca all laugh at the heat. Save the delicate ones for spring and fall.

My petunias made it through the rest of that summer after I switched to deep morning watering and added mulch. Now the only flowers I lose are the ones I forget to check on.