Documents: Latest From: The Real Dirt:

Heirloom Tomatoes are Worth the Extra Work!
by John Harmon
July 21, 2002

As gardeners become skilled at growing tomatoes and master the art of harvesting loads of ripe red fruit every year from the regular seed catalog varieties they are likely to go looking for more challenging fruits to grow. Heirloom tomatoes will provide that challenge.

Growing heirloom tomatoes is a labor of love because you are not likely to get the production you are used to from the hybrid varieties. These tomatoes were usually bred for flavor, not resistance to disease or pests. To give you the best chance of harvesting nice ripe heirloom tomatoes you will have to provide a growing environment that starts and stays disease and pest free.

Right from the beginning make sure your potting mix is sterile before you plant the seeds. A little extra care here really pays off later because you will have strong healthy transplants when it's time to set them out. I like to use commercial starting mixes like Redi-Earth but any well draining sterile potting mix will work.

To get the best seedlings they will need at least 12 hours of direct sun daily. Here in the north you can provide them with 16 hours of artificial light indoors to get them going. Most of the heirloom varieties will take over 80 days so start them indoors in March. The more natural light you can give them the better they will do. I start mine in front of the windows and give them artificial light to boot. They can never get too much light.

The work really begins when you set the plants out in the greenhouse. If you're using soil in beds it will have to be sterilized. Pathogens that wouldn't hurt many of the newer hybrid varieties will quickly kill off heirloom varieties with no resistance. Greenhouse beds where you have grown tomatoes in the past can hold soil borne diseases from previous years and pass them along. Use new beds and soil whenever possible or "solarize" your soil.

This is done in the summer and right now is a great time to get beds ready for next year. Give the soil a light watering. It should be damp but not wet. Cover your beds with a layer of clear six-mil plastic. Hold it down with some two by fours spaced every couple of feet. Then put on a second layer of clear plastic. The idea is that when the sun shines on your beds the soil will heat up. The double layer of plastic will hold the heat. It is recommended to leave the beds covered for at least a month during the hottest part of the summer. This treatment is simple and easy and it will kill many of the soil borne pathogens that would otherwise attack your tomatoes.

Another important factor is the water. Never use cold water on tomatoes hybrid or heirloom. Warming the water to at least 55 degrees F. will avoid shock and help to prevent mildews and molds. Another thing that will damage your plants is chlorine. It is used in almost every cities water treatment to kill germs. If you're on city water it's likely got chlorine in it. Fortunately it will evaporate very quickly if exposed to the air in an open container. You can kill two birds with one stone by pumping your water into an open topped 45 gallon drum that's painted black and gets sun all day. Your water will warm up nicely and that nasty chlorine will be gone. Just put a lid on it to stop mosquitoes from using your water barrel as a breeding site.

With clean soil and clean water you will get the best yield possible for your variety. That may not be much with heirloom varieties but the taste will be worth it.

Harvest your fruit when it is fully ripe. Vine ripened tomatoes will taste better than any commercial tomato that is picked at what they call the "mature green" stage. Never refrigerate tomatoes! Just let them sit on your kitchen counter out of direct sun for a few days until they are just right to eat. The tomato will continue making sugars after it is picked and you can enjoy them at whatever sugar level suits you.

There's a great little booklet that you can get about growing tomatoes. It's called " Gardening Secrets For Growing Huge, Fruit-Packed Tomato Plants" and you can order it online with a credit card and download it instantly. I bought one and it comes as an MS Word document. It's 32 pages and only costs $2.99 US or about a million Canadian. The sales pitch is " Learn hundreds of organic gardening tips for growing tomatoes with Gardening Secrets For Growing Huge Fruit-Packed Tomato Plants. Whether you’re a beginner gardener or a tomato gardening enthusiast, you’ll learn everything you need to know to grow tomatoes like a pro." The sales pitch is slightly overstated but there is some very good information in the publication and it downloads quickly as a Zip file. Look for it at

For heirloom tomato seeds you can't beat the over 3000 tomato varieties available along with 650 kinds of peppers, 3,500 beans and thousands of other rare varieties for your garden and greenhouse from the Seed Savers preservation farm in Decorah, Iowa. You will find them at

The extra work that heirloom tomato plants require and the smaller yields are more than compensated for by the great tastes and unusual colors these old-time tomatoes can provide.

John Harmon owns and operates Tropicals North. Write John at The Real Dirt, c/o 211 Wood St., Whitehorse, Y1A 2E4 or e-mail

  • New Eden
  • Kids Garden
  • Plant a Row Grow a Row