How to Harden Off Tomato and Vegetable Starts

It’s May and gardening season is in full swing. Our garden beds are ready and the weather is warming up.  Before you actually plant, it’s important to take your time when it comes to moving your new seedlings to the great outdoors. This applies whether you grew your own tomatoes, vegetables and flowers from seed or bought them from our greenhouse. Moving your plants from the house or greenhouse directly into the garden without giving them time to adjust will mean you’ll lose most, if not all of them. At the very least, you’ll set the plants back weeks due to transplant shock. This slow transition from indoors to the outside is called “hardening off”. Hardening off plants gradually exposes them to outdoor light, wind and temperatures. The process is easy, but it takes time. In fact, you should plan on a week or so to get your immature plants ready to transplant into the garden. 

On the first day, pick a sheltered, shady spot under a tree or on the patio and leave them there for 5 or 6 hours. Bring them in that night. The second day, place your plants where they will receive morning sun and afternoon shade. This will help your plants adjust to direct sunlight. Leave them in this spot for 6 to 7 hours. Over the next few days, gradually increase sunlight exposure until your young plants are sitting outside for the entire day. Once this has been accomplished, start leaving them out later at night, always keeping an eye on the nighttime temperatures. If the temperatures at night fall below 50 degrees, bring them inside. After 7 or 8 days, your plants should be ready to plant. Even then, you'll want to keep an eye on the forecast. 

The average last day of frost is May 10, but this can vary greatly. May's weather can change quickly, so keep a  frost blanket handy to throw over your plants to protect them. Make sure you keep your plants watered during this hardening off process. Being outside means they will dry out faster, so keep an eye on the watering. Finally, when you’re ready to plant, pick a cloudy day. This will help your plants make the transition from container to the garden even easier.