Growing Heirloom Tomato Plants from Seed

Starting Heirloom Tomatoes from Seed is Easy!

Note: This article was originally posted March 18, 2013. The links have been updated for 2014. 

Last week I started 25 varieties of heirloom tomato plants from seed; planting more than 500 seeds!  It would appear that I have a problem controlling myself, but after last year’s success at selling heirloom tomato plants at the Kootenai County Farmers’ Market, I’m going to offer plants for sale again (click here for 2014 Tomato List).

Growing heirloom tomato plants from seed is fairly simple, and I love the anticipation of seeing the first tiny sprouts appear.  So grab a packet of heirloom tomato seeds and let’s get planting!

Getting Started

Timing Is Everything.  It’s a good idea to start your tomato seeds about 8 weeks before the last average day of frost (May 15th in northern Idaho). Anytime within the next three weeks is prime-time to start your seeds.

A plastic shoebox, turned upside down, becomes a mini-greenhouse.

Gathering Supplies.  Retailers and seed catalogs would like you to think that you need expensive equipment (heating mats, grow-lights, prepackaged kits, etc.) to successfully start seeds. Not so. All you really need is a sunny window, quality seed-starting mix, and some up-cycling ingenuity!  Of course, if you don’t have a sunny window, a grow light will come in handy, but chances are you have a window that will work for at least a couple of pots of seeds.

Ground coconut husks can be used in place of peat.

The Scoop on the Dirt.  For best results use a commercial seed-starting mix or mix your own. Soil from your garden is a no-no — it’s just too heavy.  Commercial mixes are generally a combination of sphagnum peat moss mixed with perlite or vermiculite. Some mixes contain a wetting agent and/or fertilizer. I use a mix of peat and perlite (about 5 parts peat to 1 part perlite). Another option is coconut coir (ground coconut husks). Burpee sells dehydrated blocks of coco-coir which expands to 8 quarts of material when water is added. I add one block to 8 quarts of mix. Unless you are planning to start mass quantities of seeds, one bag of seed mix (8 to 10 quarts) is all you will probably need.

Using newspaper to make pots.

Pots.  There is no limit as to what you can grow your seeds in. A quick look around the house will reveal lots of options: paper cups, egg cartons, paper milk cartons, or cardboard rolls from paper towels and toilet paper.  There’s even a nifty little pot maker you can purchase to make pots out of newspaper.  Intriguing, but I don’t have time to make my own pots. I use 3″ peat pots, and I don’t recommend using anything smaller.

Recycled lettuce containers make perfect mini-greenhouses for seed germination.

Mini Green Houses.  Tomato seeds need a warm, moist environment to germinate. Again, no need to purchase a seed-starting kit. All you need is a plastic lettuce container (or any waterproof container that is deep enough to hold your pots with a little head room). Nestle the pots in the container, pop on the lid, and viola!, a perfect mini-greenhouse. No lid? No problem, stretch a piece of plastic wrap over the top and secure with a large rubber band. The lid is only needed until the seeds germinate, then it can be removed.

Planting Seeds

Well moistened peat pots planted with 5 seeds in each.

With your supplies gathered, it’s time to plant.  I’ve been using this method for several years with great success.

1. Wet your peat pots with warm water.  I make sure they are well saturated. (I don’t wet my soil before planting. However, you are not using peat pots, you will want to dampen your soil — don’t make it soggy!)
2. Fill the peat pots about 2/3 full of seed-starting mix.  Don’t compact the soil, but lightly press down.  Using a spray bottle, spray warm water on the soil in the pot to moisten.
3. Place your seeds on the moisten mix.  I place 5 seeds in each pot and transplant the starts into individual pots later.
4. Spray the seeds with water just to dampen.
5. Cover the seeds with about 1/4 inch of seed-starting mix and spray the soil again.
6. Place the lid on your container and put it in a warm, sunny spot.
7. In 7 days your tomatoes will sprout!

Heirloom tomato seedlings take about 7 days to germinate. The seed above were planted on March 11…on March 16 the soil was still bare. As if by magic, the seedlings appeared overnight and greeted me on March 17.

And that’s just how easy it is! Once your seed germinate, you can remove the container cover or prop it open. If the seedlings start to touch the lid, you will need to remove it.  Don’t let your pots dry out — keep them moist, but not soppy-wet. The seedlings do require daily monitoring of  moisture levels.  When your seedlings develop their first set of true leaves, (about 3 weeks after seed starting), they will be ready to transplant into individual pots (one plant per pot).

Of course, if you don’t want to grow your own, I’ll have plenty of heirloom tomato plants for sale by the middle of May!

What types of heirloom tomatoes are your starting this year?  Let me know in the comments below.