Top Tips For Getting Your Tomatoes Off To A Good Start

I used to get so excited when TomatoCulture’s heirloom tomato plant sale kicked off in the spring. We always had a flurry of activity at the Downtown Growers Market every Saturday from opening day until the end of May. During these Saturday morning’s, I would receive a lot of questions about how to plant and care for newly purchased tomato starts. I wrote this blog to provide some tips on getting your plants off to a great start.

Harden Off Your Plants

Most tomato plant starts have been raised in a protected greenhouse so they have not been acclimated to the outside. This means they have not been exposed to full sunlight, high winds or cold nighttime temperatures. Therefore, it is important that you “harden off” the transplants before planting them outside permanently. This process involves putting the plants outside in sunlight each day, starting with an hour, and gradually increasing the exposure time by one hour each day over a week. This gradual acclimation helps the plants get used to direct sun, wind and temperature changes. If the forecast calls for extreme cold or foul weather, keep your plants inside and then resume the hardening off process on the next day. Look for plants in deeper as opposed to wider pots, which allows you to keep the plants in the pots for as long as needed while you harden them off and wait for the correct planting time. 

Plant at the Right Time

Spells of warm weather during the early spring ignites the gardening bug in people and compels them to start planting. There are many plants that you can start early, but tomatoes are not on that list. My general rule of thumb is to wait until the nighttime temperatures are consistently at or near 50 degrees. An exception to this rule is to plant sooner but provide protection. If you want to plant earlier, look at purchasing row cover fabric or some other season extender to protect the young plants from the volatile spring weather. Covering your plants with fabric will keep some heat in and help keep out early spring insects like the beet leafhopper, which spreads the fatal curly top virus. I have also had success wrapping individual tomato cages with thin plastic sheeting. The top can be opened on warm days to vent the heat.

Provide Some Shade 

Tomatoes do like a lot of sun and warmth, especially in northern climates, but here in the high desert, over-exposure to sunlight can be a problem. When deciding where to plant your tomatoes, the best possible location is somewhere that gets late afternoon shade (after 2pm). Afternoon shade gives your plants some protection from the brutal afternoon sun and heat, which can cause a number of problems for your plants, including reduced vigor and poor fruit set. Like humans, tomato plants like a bit of shady relief during the hottest part of the day. If your location does not have any natural shade, you can create shade for your plants with shade fabric. If you live in a drier climate, you can get away with spacing your plants as close as 30 inches apart. The closer spacing helps provide thick leaf cover to shade the interior parts of the plant, cool the flowers and protect the fruits from sunscald. I have also grown heirloom tomatoes in the Mid-Atlantic region, where the temperature often hits 100˚ in the heart of summer and my plants in locations with late afternoon shade did the best.

Support Your Plants

The best material for do-it-yourself tomato cages is concrete reinforcement mesh, which you can buy in rolls at home improvement stores. To make a cage that is 24” in diameter and five feet tall, you will need to roll out about 7.5 feet of wire mesh and cut it with heavy duty wire cutters or a hack saw. This size cage will fit nicely around your plants, provides strong support, and allows for easy access for picking ripe tomatoes. The flimsier store-bought cages are fine, too, but you will likely need to add a stake for extra support and to prevent the cage from falling over when the plant gets large and loaded with fruit.  

Water Your Plants

The ideal watering setup is drip irrigation on a timer. This strategy allows you to water evenly and consistently without having to think too much about it. Also, when you are away during the summer for extended periods, drip irrigation on a timer eliminates the hassle of having to find someone to water your plants. 

Another critical part of your watering strategy is to mulch your plants once they have taken hold and started to grow. It is important to cover the soil to keep the roots cooler and the soil more evenly moist. You can mulch with three to four inches of just about any type of organic material. You can mulch with finished compost, straw, hay, pine needles, newspaper, cardboard, or dried grass clippings that have not been treated with herbicide. To make a finer mulch, run over your organic material with your lawn mower to shred it into smaller pieces. 

Feed Your Plants

First and foremost, tomatoes love rich, loamy soil; therefore, work on building your soil over time by adding lots of organic matter and compost each spring and fall. In the meantime, you can work a balanced fertilizer into the hole at the time of planting. At this stage, you want to be sure to choose a fertilizer that is high in phosphorus and not too high in nitrogen. High nitrogen fertilizers will result in a lot of leafy green foliage, but few if any flowers and fruit. The three letters for fertilizer are N-P-K, for nitrogen, phosphorus and potassium, respectively. Look at the numbers corresponding to these three ingredients on the fertilizer bag. The second number should be higher than the first.

It is also important to get a fertilizer that includes calcium and magnesium, two important micronutrients for tomatoes. Check with your local nurseries for the best fertilizer choices. Add a half cup of fertilizer to the hole at planting time, and then fertilize again when your plants start to flower. When the first flush of flowering occurs, pull back your mulch and scratch another dose of fertilizer into the soil surface and add water to help the fertilizer penetrate the ground. I also like to supplement with a foliar fertilizer from a sprayer. Organic fish fertilizer works well and gives the plants a low dose of added nutrients on a regular basis. I spray every two to three weeks early in the morning, when the leaf stomata are open, and coat the top and bottom of the leaves.