I just planted tomato and pepper seedlings (both are around 5-8 inches in height) two days ago in the main garden. But the forecast for my area NOW is calling for low 40's at night this week instead of the upper 50's/low 60's as was previously forecasted last week.
Are they going to be okay during these cooler temps at night? Then again now that they're planted, I guess don't have a choice.
Peppers will be a problem. Tomatoes can handle it for short duration like hours at a time, but not if this goes on for several days -- turns purple and eventually yellows. Peppers can sulk and stop growing/become stunted.
How many plants are we talking about? You can cover them individually with 1/2 gallon or gallon size plastic jugs with bottoms cut off, leaving the top open. If using tomato cages, you can wrap the cages with plastic bags.
When plants are larger, you can cover with 5 gal buckets or cover their cages.
Or you could cover the entire row/raised bed with hoops and floating cover or plastic sheeting.
Key when covering is to remove the covers the next morning as soon as temperature warms back up, and especially when sunlight hits unventilated enclosed covers.
Temps like that are pretty common here right after planting tomatoes and peppers out. They seem to get by OK. As noted a bucket or gallon bottle with the top cut off makes a good cover for nighttime. Hot caps are a good investment.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-