Thessaloniki Tomato
(Solanum lycopersicum)

For detailed step by step instructions for growing the Thessaloniki tomato, visit our growing tomatoes page.

Heat Tolerance:  This tomato likes heat but a string of days in the 90's can cause blossom drop.  This stress can take a week or more to recover from, delaying and reducing harvest.  Woven shade cloth supported above the plants by poles is used by some growers to moderate temperature.

Fruit: 5 oz average, round, slightly ribbed, red fruit. Grows in loose alternating groups which ripen sequentially.
: Juicy, firm, average tomato flavor. A bit seedier than most.
Disease Resistance
: Good. Late blight: Average
: Excellent.
Maturity: Mid season
: Heavy
: Heirloom, indeterminate, slicing.

Thessaloniki Tomato Germination Data

Germination rate: 80%

Time to Germination:
     1st up: 5 days
     Average: 5 days
     Last up: 5 days

Seed Info:  2 years old.

We use older seed regularly with success.  Germination rate is still excellent for this variety.  Older seed can take longer to germinate.

Starting Seed Indoors:

  • Planting depth:  1/4 inch
  • Soil Temp.: 75-80˚F
  • When: Plant 6-8 weeks prior to the date your garden soil reaches +65˚F in your area.
  • Soil: Seed starting soil or mix your own (see growing tomatoes page for recipe).
  • No. of seeds: 2-3 per cell
  • Cell size: 1 x 1 x 2" (Length x Width x Depth) Larger sizes are fine.
  • Water with warm water/fertilizer solution (see growing tomatoes page).


  • When: Seedlings are 5-6 inches tall and sturdy.
  • Pot size:  6" tall or more.
  • See growing tomatoes page for transplanting details.

Planting Seedlings Outside:

  • Full Sun
  • Soil Temp: +65˚F
  • Hole depth: 12+ inches
  • Spacing: 24" apart.  36" apart if you need to walk between plants.
  • Planting depth:  Bury root ball and most of the stem.  Keep 3 or more leaved stems above ground.
  • Windy Locations:  Plant at a slight angle away from the prevailing winds.  This greatly reduces breakage.


  • Without Rain: 1 - 2x / week (depends upon temperature and soil type).
  • Timing:  Late morning or early afternoon.  The sun will quickly dry the leaves reducing the occurance of disease.

Your soil type will affect water needs.  Carefully observing the plants and how long your soil remains damp is the best way to learn how to manage your unique conditions.

Many diseases that attack tomatoes, infect the plants when water stays on the plants for long periods or splashes up from the ground.  Avoid getting water on leaves as much as possible.  If you must water on cool cloudy days, wet the soil below the plants, ie. keep the leaves dry.

Seed Genetics: Non-hybrid, characteristics usually "fixed" through inbreeding.

Seed Collecting: Seeds will come true if crosses with other varieties are prevented. Tomatoes mostly self pollinate anyway but to prevent hybrids, bag an unopened flower with spun bonded row cover material. You can vibrate or gently tap the flower stem to aid in self pollination. Remove bag when fruit starts forming or petals fall. Mark stem with a string so you can find it later.

  1. Pick fruit when very ripe.
  2. Spread seeds on a paper towel to air dry. Don't try to get all the pulp off the seeds. You could damage the seeds and its not necessary.
  3. Mark the variety on the towel.
  4. Move seeds around on the towel in a day or two to prevent them sticking to the towel.
  5. Store when completely dry. Keep in a cool dry environment. If the air is really dry (you run a dehumidifier or live in Arizona) or really humid then store in sealed moisture proof containers such as glass jars or foiled ziplock bags. Freezer bags are the next best choice.
    If your humidity is "normal", you can use a paper bag. The seeds will be able to breathe and will last longer.

Life Cycle:
     Zone 10 or lower:  Grow as annual
     Zone 11 or higher:  Perennial

Indeterminate:  Plant will continue to set and ripen fruit until frost.

Staking:  These plants cannot support their own weight.  Use stakes, tomato cages or trellis if you want them to grow upright.

Growing on the ground:  Plant the seedlings at about a 20-40 degree angle from the ground so the stem doesn't snap as the plant gets heavy.

  • Advantages:  Less expensive, less work then staking.
  • Disadvantages:  Lose more tomatoes to pests such as beetles and slugs.  Uses up more space in the garden.

Pruning: If you have a long growing season, indeterminates can get quite tall.  Pruning the terminal leaves at the top of the plant will induce new branches to form lower on the plant and help control height.

If you are growing tomatoes as a perennial, biannual pruning will reduce the quantity of stems and leaves that are being supported by the root system and improve productivity. 

  1. Prune (head back) to between 2 - 3 ft high
  2. Thin, if necessary, by removing some of the oldest branches.
  3. Fertilize.

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Note:  Germination performance is affected by many factors including temperature,  package type, seed age, etc..  All our seeds are grown under the same conditions of moisture, temperature, soil content and light unless otherwise noted.  This allows us to compare varieties so you can see which ones are easier to grow.  But, since your conditions may differ, you may not experience the same results. 

These are not statistically significant sample sizes.  To do so would require we plant over 6000 tomato seeds!  But we do have germination data from previous years.  If data appears atypical, we'll note it.