I just saw this question: Harvesting sunflower seeds and planting the same year

Now I wonder whether the same is valid for tomatoes, too? About a month ago, I started harvesting the first tomatoes of a fast-ripening variety (42 Days) here[1]. Would it be possible to start a few new plants this year?

The current plants are already dying, so I hope to get at least some more before winter... (Don't know why, that would likely be the topic of another question.)

[1]Middle of Germany, equivalent to hardiness zone 8b.

  • 1
    Here's a handy tool for finding your hardiness zone in Germany: plantmaps.com/… I double-checked, all zone numbers temperature ranges on this map match to the ones on a US map. So a Zone 7 in Germany means the same as it does in the US.
    – GardenerJ
    Jul 29, 2015 at 20:07
  • Great, thanks! Added the information to the original post.
    – anderas
    Jul 29, 2015 at 20:35
  • For the record: I tried to plant some seeds directly from the fresh tomato. None of them sprouted, so the answer might actually be: No, it doesn't work reliably.
    – anderas
    Sep 7, 2015 at 9:11

1 Answer 1


Yes, tomato seeds will germinate without a year having to pass first (even right away, before you even dry them). Just make sure it's not too hot or cold for them to germinate and grow well. If it's consistently very warm in your house, they might have trouble, especially if you have artificial lights on top of that (since artificial lights can produce heat; even the low-heat ones, like CFLs, will make the room more noticeably warm when it's naturally kind of warm).

Edit: However, it should be noted that tomatoes germinate faster in warm conditions (as long as it isn't too warm) than they do in cool ones, in my experience.

Anyway, I've grown newly harvested tomato and pepper seeds before with good results. They don't need to be aged. New is good.

As long as your growing season is long enough and your tomatoes tolerate the temperatures they will be in (indoors and outdoors), you should be fine.

Edit: If you want the plants to fruit indoors (rather than start them indoors and transplant them outdoors), as Stormy seemed to me to understand, then be sure to give your plants enough red light (which helps with flowering; blue light helps with leaf growth), soil, and enough of the proper nutrients. I was assuming that you were wanting to start them indoors while it's still summer outside, and then transplant them outside for the remainder of the season, hoping to get some extra tomatoes during the rest of this season. Whatever season it is, indoors or out, you'll probably want your nighttime temperatures to be between about 55° F. and 70° F. Many people keep their house above 70° F. at night; so, that's something to watch out for. Daytime temperatures should be between about 60–85° F. Flowers might drop if it's too hot.

If you have heat and cold tolerant tomatoes, parthenocarpic tomatoes or such, then your plants may set fruit in a wider variety of temperatures. See this question/answer for information about such varieties.

I concur with stormy about low nitrogen fertilizer for indoor use, but if your soil outdoors is already low in nitrogen (like mine probably is), then adjust accordingly. However, for plant growth, I haven't had issues using an even fertilizer (20-20-20), even though slightly less nitrogen than potassium is generally recommended for tomatoes. However, be careful, anyway, I've found that my indoor tomatoes can get burned by 18-18-21 fertilizer (but 20-20-20 fertilizer doesn't burn at all), which doesn't make a lot of sense, unless with the 18-18-21 fertilizer they're just using a faster-release nitrogen, or the potassium didn't dissolve in the water properly or something. That's one reason I like to mix fertilizer proportions myself (I know it really is what I think it is, and I can adjust it if it isn't what the plants need.)

However, as far as fluorescent lights go, be careful there. A lot of people will tell you to get only 5000-7000k bulbs, which is great for growing seedlings into plants, since it's high in the right kinds of blue light—but lower color temperatures are actually higher in red light, which is important for flowering. Lower color temperatures also help protect against damping off disease, in my experience. Plants don't lean toward the lower color temperatures as quickly, though (but when they adjust to it for a while, they do lean toward it faster than they initially did). They can still grow leaves on lower color temperatures of fluorescent bulbs (I know from experience), although 6500k might be more ideal for that.

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    As long as they have enough light...they'll need extra light in Germany for the winter to produce fruit. Careful with fertilizer (low Nitrogen) and if in pots, use sterilized potting soil, add mychorrizae (sp), bacteria (lots of great soils for pots come with this important life additive)...do not use garden soil in pots! Get a few serious grow lights...'Blaze King' is a great inexpensive fluorescent that would work...around $150ish dollars. Ask for the red spectrum fluorescent, not the blue. This fixture is 4'X12", good for 2 plants maximum.
    – stormy
    Jul 30, 2015 at 21:17
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    Thanks for the addition, would add another upvote if I could ;-) You were right about about my intention of hoping to keep them outside. If the first fruits really mature in under two months (as the description of that variety suggests), that might hopefully be early enough. If not: Well, I already saved some seeds and put some into a pot. My question was about whether that might actually work at all, and my "experiment" is now to see whether it works. Just for fun, nothing to lose if anything goes wrong ;-)
    – anderas
    Jul 31, 2015 at 10:41

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