April 17, 2013

How to grow tomatoes from seed.

It's the perfect time to sow tomato seedlings. It's ok if you accidentally sowed them too thickly like
this, tomatoes transplant well at most any stage.
If you're anything like me, you have taken great effort to try and grow your own tomato seedlings, only to pass a table at your local Home Depot and see these incredible beautiful, thick, lush green and ‘healthy’ tomato transplants that make your own look like the leftovers, the runts of the litter, but let me assure you right now - you will never be able to get your plants to look as lush  or with stems as thick as the commercially grown plants, and that's OK. In fact, it's better than OK, and here's why...

Take pride Mr and Mrs Tomato parent, for your tiny offspring will outgrow and out produce these high-school, one-hot wonders once they get going in June. Why? Well, those nice-looking plants that you see on the shelves at the big box stores are steroidally enhanced. They have been drenched with hormones with every thing from those that cause thick-stems and dense growth, to those that force long roots. They have even been hit with some that cause the plants to blossom at young age. In a plant-way, they are mentally disadvantaged,if not chemically messed up. In the end, your home grown ( even thinner) seedlings will still have a better chance of becoming a doctor, a hero or even the kind of the tomato world by the end of summer.

So relax, and grow your own tomato plants and get over the fact that no home grown tomato plant will ever look like a enhanced seedling from a big  box store. But if you still want bragging rights, you can raise naturally healthy seedlings, and here's how: 

Here are my best tips and tricks for raising tomatoes from seed:
Some of the varieties I am growing this year. I can't wait! What are some of your favorites?

• First choose your variety and have fun  -
I’m not going to talk about varieties, leaving that choice up to you. There are so many choices today, that you can really have fun choosing the type that you like. Naturally, there are enough posts out there about choosing the best variety for your area, taste and growing methods, so go snoop around. I, personally, like a mix of colorful heirlooms and then some disease resistant hybrids. I am a sucker for those that have descriptions that say things like "this won our taste test last year".

• Use clean soiless mix and clean pots – 
This means no garden soil, but a new bag of soilless mix like Promix or a seed starting formula you like. Just never use old soil from last year, even if it is soilless – old soil is like drinking a warm glass of raw, pink chicken juice to tomatoes. They are highly prone to disease and virus’.

• Germinate at high temps – 
Tomatoes germinate best at 75º - 85º
If you didn't sow one - three seeds per pot, thin young plants when the second pair of leaves
emerge. These were sown one seed to a pot, with a heating mat.
So use a heating mat if you have one or place your seed tray somewhere warm for a few days – even if you have to place it in a cookie tray and place it on top of your refrigerator. I use to put ours on the furnace, and now I use the shelf above our Viking range ( we’re fancy, but not fancy enough to care about dirt on the stove, or scratches).

•Thin seedlings to one per pot.
 I know, it’s hard, but if you sowed 2 or 3 seeds to a pot, this should be easy. Just gently pull out the goofiest one, or sacrifice the others. Never cut seedlings out, as the remaining stem will rot and can cause an outbreak of something nasty ( i.e. raw chicken juice thingy).

Heirloom tomatoes are not only beautiful, and often more tasty, they are
also be more vulnerable to disease and virus - often becoming vector plants hosting
an outbreak, so keep them as strong and healthy as possible. No tomato is immune from
the air-borne spores which cause late blight, but with care, you can delay an outbreak.

Transplant seedlings to individual pots if you sowed too thickly. It’s OK, tomato seedlings transplant easily.

• Grow-on warm, but then adjust to gradually cooler temps.-
If you want strong stemmed seedlings, provide them with the strongest light possible, and bring them outdoors on warm, sunny days, as the wind will provide some free Crossfit sessions – it will help the weakling stems become strong, as the tension and flexing will stimulate the cellular walls to strengthen. The use it or loose it theory.

• Fertilize weekly and weakly – 
This point is so essential for success, that you have to promise me that you won’t forget – your tomato plants are babies, and they need vitamins and proper nutrients. Period. 
Last year I grew some plants in felt bags, the larger the better. The black helped
plants absorb heat, and I used sterile soil mix with tomato cages. The only
problem? These had to be watered twice a day.

Know that most sterile soilless mixes can’t provide enough nutrition ( check if your brand has fertilizer already added). Here where it gets squidgy – sure you can use organic fertilizers, but since you’re using a peat-based soil that has been somewhat sterilized ( no soil is completely sterile), organic fertilizer needs time to breakdown, and, well, organisms ( think yogurt in belly or gut flora). Without going into great detail, trust me here too – water soluble salt based fertilizer augmented with micro nutrients is best, and I save the natural, organic stuff for the garden or pots, since in order for it to break down properly, I have to add it to my outdoor soil in the autumn.

BTW- a note about organic fertilizer vs. water-soluble salts - ask any chemist, most water soluble fertilizer is basically the same thing. Chemicals are chemicals, and it’s just good horticultural practice to know that a lot of this hubbub about “organic” get’s a little crazy when it comes to fertilizer for the home gardener. But that’s another post. If it makes you feel better, at least choose a fertilizer that is low in nitrogen, and higher in phosphorus, but some nitrogen is OK for the baby’s first 8 weeks when it need to grow green leaves.

A high phosphate ( the second number) fertilizer is 'THE SECRET' for awesome tomatoes. You don’t want to mess around with nutrition and food crops, especially if you are serious about growing tomatoes as they are especially heavy feeders. Miracle-Gro 10-10-10 formula is just 'white bread' fast food for them.Sure, you will end up with giant, lush 15 foot tall, dark green plants but they will produce few tomatoes ( sorry sis, but I keep telling you this!).  

Commercial brands marketed as 'Tomato Fertilizer' are also not all the same thing - many have more nitrogen ( the first number) and other don't. I can never figure out how so many brands can be so different? Just be sure that the middle number or the last number is higher than the first. I personally don't use Fish Emulsion fertilizer as I use a peat-based mix so I need a more synthetic mix, I also need micro nutrients, so I look for brands that have boron other micro nutrients.

In the garden I need to plan a year in advance, as I use manure. DO NOT add manure in the same year that you are growing plants, and all you will get is foliar growth. Tomatoes LOVE manure, but almost too much. Your plants will look amazing, but you will only get 2.5 tomatoes per plant. I promise. Dig in manure a year in advance if you can, or do what I do - turn it in at the end of the summer.

I use a good leaf-based compost and slow-release organic fertilizer dug into the ground in the autumn so it can start working, and then I augment with a liquid or granular feed (like 5-17-12) in the summer. I don’t care if you don’t tell anyone and you just tell them that you use fish emulsion and organic monkey poo from the Amazon, (but don’t use that black gold fertilizer sold for growing Mary Jane that comes from the Amazon River mud, it may have heavy metals in it).

Tomatoes are so prone to disease, that great care must be taken to keep plants as disease
free as long a possible, as most diseases come from the soil, or from the airborne sources
attaching to the plants when the foliage is wet. I avoid disease for as long as possible by
growing plants in containers with sterile soil, placed on hot gravel that helps the leaves dry off
after a morning watering. Fertilizing is key under these conditions.

• Grow you tomatoes in a new place each year, or in pots.
I grow most of my tomatoes in large tub or pots, and usually they are the ones that grow best. I use expensive Pro-Mix peat-based potting soil, and I never re-use it. When I do, my crop is less than half as good, so I learned my lesson. I think the Scott’s Miracle grow mix is good too, but remember, it has fertilizer in it, which will leach out by the time your fruit is ready, just augment it with Phosphate.

When planted out into garden or field soil, plants do best if you can find a new
plot of land each year. Trying to grow tomatoes in the same place each year
only encourages soil-borne disease, and it's almost impossible to avoid them this way.
Use a plastic mulch to keep soil from splashing onto the foliage.

If you plant your plant out into a garden, a raised bed or in the ground - transplant them into medium-rich  field soil and space 12-24" apart for determinate varieties, 24-36" apart for indeterminate ( the sort you don't stake) For those that you do stake, space them 14-20".  

Water young transplants with a high-phosphate fertilizer solution after transplanting. For the earliest crops, set plants out around the last frost date - avoid setting out unprotected plants until night temperatures are over 45°F (7°C). Any frost will cause severe damage!

You can’t fake it with tomatoes, they seem easy, but the proof is in your harvest! Feel free to send me any questions you have, and I will try to answer them in a follow-up post!


  1. so jealous of your seedlings! i had some perfectly lovely tomato seedlings (cherokee purple, pink brandywine, italian beefsteak, etc) as well as thriving cucumber, eggplant, basil and on and one. then, my cats discovered their thumbs and pulled off coverings, opened doors on their mission to eat the tops off of all of my plant babies. they also ate and then played soccer with the remains of my lemon grass starts.

    maybe i can just plant the cats directly in the garden....

  2. Oh Nanne, well, at least you can alway grow more, and the kitties had fun. If you thin that is bad, Lydia one mama dog got into the baby chicks yesterday - and, well, I will leave it at that, and I would have to censor the comment. Let me put it this way - there is a reason why they make squeaky toys shaped like little animals, suddenly they don't see that cute anymore. Oh, that Mother nature!

  3. I have not been very successful with tomato seeds, but maybe I should try again.

  4. I think too many gardeners forget, after months or years, to have fun too. :) There are so many beautiful, fun things to grow, taste, and enjoy.
    And tomatoes are some of my favorites. So many varieties and so many uses. I think my garden is usually about 1/3 tomatoes.

  5. Thanks for the in-depth info on tomato fertilizing. I love how even as an experienced gardener I can always learn something new when I open myself up to other's ideas. Why again- do you avoid fish emulsion with your peat based planting mix? I keep experimenting with what I use as a fertilizer for my seedlings and I'm not sure I have found one I like yet. Also For perennial seedlings? I have been using Daniel's. Any thoughts? Thank you!!

  6. Christi, if Daniels has kelp added, it might be better, but here are my thoughs on Fish Emulsion - first, nothing attracts fungus gnats faster ( the green, slimy algae and tiny black flys one gets on the surface of seedling soil), second, most Fish Emulsion, such as Alaska brand by Scotts, has an analysis of 5-1-1 which is too not too high in nitrogen , but it far too low in phosphrus and potash, kelp added 6.3.3 is a little better. So if you can find that, great. But the problem I have with organic nutrients is that they are not as fast acting at pure chemical based ones, the elements need to decompose, basically, and that takes time - too long for seedlings to appreciate. Plus, Fish emulsion needs soil bacteria to convert it to be best form of nitrogen which the seedlings can use, but in a sterile soiless mix, it is of minimal value.

  7. Thanks for the in-depth info on tomato fertilizing. I love how even as an experienced gardener I can always learn something new when I open myself up to other's ideas. Why again- do you avoid fish emulsion with your peat based planting mix? I keep experimenting with what I use as a fertilizer for my seedlings and I'm not sure I have found one I like yet. Also For perennial seedlings? I have been using Daniel's. Any thoughts? Thank you!!

  8. Thanks Matt! Just what I needed to know. Your blog is one of my favorites!

  9. When many people hear the term "vegetable garden," they immediately imagine digging around in the yard and if you have the space for it,great!But even if your garden space is limited,compact containers can help certain plants to thrive even if they're hanging on your windowsill or porch.

  10. I tried starting several kinds of tomatoes inside last year and initially became discouraged when they failed to look like the ones at Home Depot... nevertheless they turned out great and produced a lot of tomatoes which had me acting like a proud parent. Thanks for this post, picked up some very helpful information that I am going to try this year!

  11. I recently stumbled upon your blog. Fantastic post. I just ordered some water soluble salt based fertilizer with micro nutrients for my tomatoes, can't wait!


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