How to Prepare Tomato and Vegetable Starts for Transplanting

As planting time approaches, it’s important to include time for acclimating your tomato and pepper plants to the outdoor garden environment. This applies whether you grew your own tomatoes and vegetables from seed or bought them from our greenhouse. Allowing adequate time for warm-weather crops to adjust to the outdoor garden environment will help reduce the stress brought on by exposure to sun, wind, rain, snow and fluctuating temperatures. This is often referred to as 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, allowing them to adapt and adjust to their new environment in stages. The process is easy, but it takes time. In fact, you should plan for a week or so to get your immature plants ready to transplant into the garden. Keeping in mind that May 15 is our average last frost date, the days leading up to Mother’s Day (May 14) afford a good time to start the hardening off process.  

 

On the first day, pick a sheltered, shady spot under a tree or on the patio and leave them there for 3 or 4 hours, then bring them back inside. 

 

The second day, place your plants where they will receive morning sun and afternoon shade. Morning sun is not as harsh as afternoon sun. This will help your plants adjust to direct sunlight. Leave them in this spot for 5 to 6 hours.  

On the third day, increase the exposure time to direct sun and leave your transplants out after dark.  

On the fourth day, if the temperatures are mild, leave your starter plants out all night.

Follow the same routine for days five and six and seven but be prepared to bring your plants back in if the nighttime temperatures fall.

After this amount of time, your tomato, pepper, and vegetable seedlings should be ready to plant in the garden. 

Even then, you'll want to keep an eye on the forecast. The weather in May can vary greatly. Be prepared to bring your plants back in if the nighttime temperatures fall. If they’re already in the ground, cover them with Floating Row Cover 1/2 ounce (5° above ambient temperature) or N-Sulfate 1.5 ounce (10° above ambient temperature). Don’t use plastic. Insulated Plant Protectors act as mini greenhouses to protect your crops. If plants are small enough, throw a box over them to keep the frost off.  

 

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.