The cups serve two purposes. One a few degrees of frost protection and... now you can put blankets on them and they won't get crushed.
Beware... Put the cups on around 3 or 4pm if you have full sun and temperatures in the 60's. You don't want to cook your plants. If it is cloudy or in the 50's, don't worry about putting them on too early.
|20-24 Ounce Clear Cups for Frost Protection: Gary Pilarchik|
|Twist the Cup in to Firm it in Place: Gary Pilarchik|
|Frost Protected Celery - The Rusted Garden: Gary Pilarchik|
I haven't grown celery before. I am guessing it can take some frost but guessing always turns out to be a risk. I purchased the cups for them and added some on peas just to see, if it matters. I'll leave some peas unprotected this week and cover others. I put the domes on below around 3:30pm. Moisture is collecting in them. Don't forget to take the domes off in the morning or you run the risk of disease and cooking your plants.
|Protecting Celery from Frost - The Rusted Garden: Gary Pilarchik|
|Celery Under a Cup - The Rusted Garden: Gary Pilarchik|
|Peas Protected From a Frost: Gary Pilarchik|