Knowing the right time to plant tomatoes depends on your soil temperature.
I’m getting lots of phone calls and emails from anxious gardeners and tomato growers wondering if it’s time to plant tomatoes yet? The answer is…it depends!
Where are you growing? What’s your average nighttime temperature? Have you thought about taking the temperature of your garden soil? Soil temperature is the key to deciding when to plant tomatoes. The soil must consistently be 55 degrees or higher for tomatoes to thrive. My general rule of thumb for tomato growers in Southern California is to wait until the end of the third week in March. Then, check your soil temperature (I use a meat thermometer!) If it’s still too cold, give it another week.
If you’ve purchased tomato seedlings but it’s still too cold at night for them to be planted outdoors, let them enjoy the sunshine during the day. Be sure to keep them somewhat protected from the elements and give them a feeding of diluted liquid fertilizer once a week. Bring them in at night, putting them somewhere away from drafts or the furnace.
An Update about Tomato Seeds….
Did you start your tomato seeds yet? If not, you still have time but not time to waste. Tomato Sseds that you start now should be ready to plant outside in 6 – 8 weeks. That sounds like perfect timing, especially if your climate will allow you to begin planting in the next couple of weeks. Spreading out your planting means you’ll be harvesting tomatoes for a longer period and that sounds really good to me!
When your tomato seedlings first emerge they’ll have two tiny leaves called cotyledon. In just a short amount of time they will develop a second set of leaves, called “true leaves”. Begin feeding once a week with diluted liquid organic fertilizer.
When seedlings are about 1 ½” tall they are ready to be potted up into 4″ containers with organic potting soil. (This will be in about 30 days.)
You”ll need to “harden off” the seedlings before moving them outdoors. Start the process by moving the seedlings outside for a few hours every morning. Pick a spot where they get a few hours of gentle sunlight and are sheltered from the worst weather extremes (eastern exposures are great). Don’t take them outside if temperatures threaten to drop much below 60ºF or if rain is imminent. After a few hours, move them back inside. Extend their time outside a few hours at a time over the next two weeks. At the same time, gradually increase their exposure to full sun and the elements. It’s not uncommon at this stage to find your seedlings bending over as they adjust to harsher conditions outside. If they start looking sad, reduce the time outside or stake them up with bamboo skewers.
Transplant outside when day time temperatures are consistently between 70-75 degrees and night time doesn’t dip below 55.