I cant tell you how many people have told me that they have planted their tomatoes alreadysome nearly a month ago! Too early, too early! When it comes to spring fever the tomato is most abused. Gardeners just cant wait to get out and dig, which is understandable, but when it comes to tomatoes it is best to be patient.
Tomatoes love two things: good drainage and heat. If you have struggled with tomatoes in the past consider what makes them most content when preparing the garden and setting your plants out.
First thing first: wait until our frost free date (on average this is May 10th, give or take a week depending on where you are located). After the frost free date the average air and soil temperature is usually warm enough for tomatoes to function efficiently. Soil temperatures should be at least 55 degrees and the ambient night-time air temperature should be above 58 degrees otherwise the plant will be stunted and less vigorous. The ideal growing conditions for growth, fruit set and ripening are daytime temperatures in the 80s, nighttime temperatures in the 60s. Ah, the perfect summer.
Now that we are ready to plant I can almost guarantee a successful season if you prepare the soil with lots of compost. This provides a slow release of nutrients throughout the entire season; it also dramatically improves drainage while retaining even moisture. Over fertilization can stress the plant so compost is far superior to weekly conventional stimulants. For example, too much nitrogen will encourage leafy growth at the expense of bloom. Lack of magnesium, which aids in chlorophyll production and respiration of plants, can also delay fruit set. Compost delivers a slow, healthy dose of both.
When you plant pinch off the lower sets of leaves and sink the plant as deep as you can. Additional roots will develop at the leaf nodes thus making a stronger plant in the long run. Once the plant is set then mulch it well in order to control weeds, prevent soil from splashing on the plant (which is one of the primary ways that disease spreads to your plant), and to moderate soil moisture (important in controlling blossom end rot). Use any organic mulching material; I typically use newspaper with grass clipping on top. I have found that the newspaper-grass clipping combo works great as winter mulch for weed control, by next spring it has broken down enough that I simply turn it back into the soil.
I cannot emphasize the use of mulch enough. It means that during times of drought you will have to irrigate very little and it moderates soil moisture and temperature which keeps the plant producing. Tomatoes rather like being a bit on the dry side and rapid fluctuations in soil moisture cause of the most common tomato condition know as blossom end rot (as well as being a contributor to blossom drop, leaf curl, and splitting fruit). When plants fluctuate between too wet and too dry, a calcium deficiency develops in the plant which then causes the blossom end of the fruit to rot. You can avoid all of this with a good layer of mulch.
I typically sucker my plants (the practice of removing the new growth that emerges between stems and branches) early in the season to encourage good branching structure; I will stop suckering once the tomatoes start to produce their second flush of fruit to ensure that there is plenty of foliage to shade the ripening fruit from the hot summer sun.
Healthy plants that receive a slow, natural source of nutrients; have adequate moisture and excellent drainage will resist pest problems on their own. If you rotate your crop, keep the garden weed-free and mulch your plants, you will further avoid many of the diseases that plague tomatoes. Remove leaves as they appear infected and dont inadvertently spread it by handling healthy plants afterwards.
And, if you have not stunted your plants by setting them out to soon, you will likely be met with bountiful success.