It’s the end of April and the nighttime low temperatures should stabilize above 50°F in the coming weeks. This means that it is time to discuss transplanting tomatoes. The reason 50°F is an important number is because below that temperature, tomato plants get their chemistry thrown out of whack and as a result get stunted and produce less fruit due to blossom drop. If you want to learn more about why this happens, click here for a good article from the USDA on the subject.
With all this in mind a common question we get is: what procedures to follow when planting tomatoes in pots or in the ground? Addressing this question requires a multifaceted answer that will be tackled presently.
If you have a favorite soil, keep using it. If you don’t know what soil to use for pots or raised beds we like Kellogg brand Raised Bed and Potting Mix. We get it from Home Depot in 3 cubic ft bags. It looks like this:
If you buy this it does not need to be amended with compost until after it has been used for a season in a garden bed.
If you are putting a single tomato plant in a pot, aim for one around 24″ across or greater. Anything less than that will constrict the plants root system and make them unhappy later in the growing season. If you want to try putting 2-3 plants in a single pot, try a halved whiskey/wine barrel. They are usually a good size to support multiple plants.
So you have your tomato plants ready to go in some soil either in a large pot, a whiskey barrel, a raised bed, or in the ground. Tomato plants are special, they can grow roots from the main stem in humid conditions or if the stem is in the ground. Consequently, tomato plants can be planted in the soil much deeper than they are in the 3-4″ seedling pots. We bury the plants so that half of the stem is below the soil. We have heard that up to 2/3 of the stem under the soil works too. This admittedly sounds really counterintuitive, but because the tomato plants will produce roots from their buried stems, it will strengthen the support system (the roots) and let the tomatoes gather nutrients from the surface all the way to deep in the soil-column. Stronger plants and better tomato harvests are achieved this way. Fred Gonsowski over on his blog has an excellent illustration depicting what should be done as well as a nice article on the subject. Go check it out by clicking here.
There is another way to bury the plants and achieve the same results too. If the tomato plant is leggy, the pot not deep enough to bury them that far down, and/or if your soil is hard and clay-like a foot below the soil, here is what you can do. You can lay the plants on their side at a shallow angle in a trough in the soil and cover them with more soil, leaving the growing tip and some top leaves above the soil. The growing tip will turn up as it grows and the plant will produce a more sideways root system that is comparably strong to the vertical.
A note for either method. Just remember to remove the leaves that will be buried under the soil. The leaves cannot produce roots so they will rot if they are submerged in soil.
I will try to keep this article updated with any other information I forget. Good luck with your gardening adventure this season!