The arrival of ninety degree F temperatures this week is tough on Front Range gardeners used to a cool spring but even tougher on plants. Plants can’t get up and go inside for a cool drink when things heat up!
Plants that grew up in a cool environment aren’t tough enough to take hot, dry conditions. Their cells and structure are simply wimpy. Expect to see some heat stress, leaf scorch, blossom drop and bolting in the garden.
To help plants transition to the heat, water with care. Vegetables like most plants need some soil drying between waterings but don’t let soils dry completely. This is especially critical until leaf tissue toughens. Some vegetables (tomatoes) benefit from more soil drying than others (onions and carrots). Bean blossoms (photo right) drop when short on moisture and pods fail to fill; they require the most moisture of any vegetable.
One note on America’s most popular garden vegetable, the tomato. Fluctuations in water supply, either excessively wet or dry will cause blossom end rot. This could have been triggered in June downpours or by July heat. It begins as a light tan, water-soaked spot on the blossom end of the fruit (photo left). These spots turn brown to black and leathery and there is no correcting it once the damage is done. Future blossoms that set fruit when moisture conditions are better won't be affected by damage to previous fruit. To manage this condition, fertilize and water properly. Use mulch to reduce moisture fluctuations.
Want more specific watering tips? Check Colorado State University Extension's Water Conservation in the Vegetable Garden garden note.
Bean blossom photo credit, Carl Wilson
Blossom end rot photo credit, Colorado State University Extension