RSS Feeds

A few tips for planting those tomatoes

Saturday - 5/10/2014, 3:27pm  ET

The weather is getting warmer, which means it's time to plant those tomatoes. Not so fast, Mike McGrath says.

WASHINGTON -- It's Tomato Planting Time!

Maybe. Lots of itchy fingers out there! Many listeners write that they want to put their tomato plants in the ground, and many have already done so. Just remember that it's not the daytime temps that count with tomatoes, peppers and the other crops of summer. It's the nighttime lows that can shock the plants and dramatically slow their growth.

Nights in the 40's won't kill your plants as impressively as frost, but it will stunt growth, and they will resent you like ungrateful children the rest of the season.

Nighttime temps are always warmer in the heat sink of the city, so it's safer to plant a little early in D.C. proper. But if you're in the suburbs, nighttime temps could still drop into the low- to mid-40s, so be patient. Early planting often equals late tomatoes.

Compost Goes on the Surface; Not in the Hole

Jarrett in Fredericksburg has a question about compost and tomatoes. He writes: "I generally dump a shovelful of compost in the hole prior to planting. Is this a good idea? Or should I spread the compost around the plant?"

You absolutely want that compost to be applied as a two-inch deep mulch on the surface of the soil, and not placed down in the hole, Jarrett. Compost applied to the soil surface will deliver a nice gentle feeding to your tomatoes every time it rains, and it provides a physical barrier against disease. The living organisms in compost eat disease spores to protect your plants against evils like late blight. Whatever you do, don't mulch with wood or bark; wood mulches breed plant disease.

Location, Location, Location!

When you plant your tomatoes, be sure to choose an area that gets morning sun; tomatoes, roses and other disease-prone plants do best when they're planted where the sun can dry their leaves off first thing in the morning. Never wet the leaves of your plants in the evening; if you must wet the leaves when you water, do that watering in the early morning.

Don't plant your tomatoes in the exact same spot where tomatoes have grown the past few years or they will suffer from a soil-borne wilt that causes the plants' leaves to turn yellow from the bottom up.

If you have no room left to rotate to, plant in containers this year or try to find grafted tomatoes whose rootstock is wilt-resistant. (Resistant tomatoes in general will have the letters "V" and "F" after their variety names.) Grafted tomatoes are being offered at more garden centers every season, so look around. And whether its grafted tomatoes, grafted roses or grafted fruit trees, always keep the graft well above the soil line.

Two Tomatoes Walk Into a Bar…

It's important to know the difference between the two basic types of tomatoes. "Determinate" varieties are bred to produce their fruits early in the season on vines that stay relatively short—about four or five feet long. Often called ‘patio', ‘bush' or ‘compact', these are the best tomatoes for containers and small-space gardens.

"Indeterminate" tomatoes typically produce much larger fruits, later in the season, on monster vines that can easily reach ten to twelve feet in length. All of the legendary great-tasting heirlooms fall into this category, and require a sturdy cage made of welded wire fencing to keep the tasty fruits safely contained.

A six-foot linear length of fencing makes the perfect cage when formed into a cylinder (which will be just shy of two feet wide). Don't stake the vine; let it sprawl inside that big cage and stake the cage so it don't fall down.

By not forcing the vine to grow straight up, you can contain a ten-foot vine in a five-foot high cage!

Tomato Planting 101

  • Dig a deep hole, remove the bottom leaves of your plants and bury three quarters of the stem underground; tomatoes — and only tomatoes — develop extra roots all along the buried stem that allow the plant much better access to water and nutrients.
  • Before you fill that hole, add the dried, crushed shells of a dozen eggs to supply the calcium that prevents the heartbreak of blossom end rot—when ripening tomatoes turn black at the bottom late in the season. If you don't have eggshells ready for this season, crush up a dozen calcium carbonate pills (like Tums) and/or use a bagged compost that's rich in calcium, like the Coast of Maine lobster compost I've see at most big independent garden centers this season.
  • Then fill the rest of the hole with regular garden soil, and apply two inches of compost to the surface of the soil to prevent disease.
  • And be sure to provide sturdy support so the vines don't sprawl—unless you're growing your tomatoes for slugs and bugs to enjoy.

Follow @WTOP on Twitter and WTOP on Facebook.

© 2014 WTOP. All Rights Reserved.