Tomato Series Part 1: The Basics, Starting With Food

It's important to know these basics about growing tomatoes:

1) They're heavy feeders and will easily deplete the soil of nutrients in just one growing season.

2) They're sun lovers and need at least 6 hours of full sun (though 8 is even better).

3) Most varieties have deep roots and need space to grow.

4) Consistent watering is critical.

5) Wet leaves are tomato killers.

Ideally, I would have started this tomato series at the beginning; where to plant them, the importance of soil, what varieties to choose.  Unfortunately, it's August and all those decisions have been made for 2020, so I'll save those topics for spring.  Instead, I'll address what's most useful for people growing plants right now, the first one being plant food.

Asking tomato growers about fertilizer is like asking elderly couples what's the secret to a lasting marriage. You'll get a hundred different answers and all of them will be right. I've heard everything from filling the holes with fish heads to mulching with egg shells and coffee grounds, to bi-weekly doses of Epsom salt.  There's no shortage of tomato wisdom and lore out there, so rather than trying to give you the definitive be-all-end-all must-haves for tomatoes, I'll simply tell you what I do.

When it comes to plant food, here's me being cheesy with my pantry:

No, I don't use these all at once.  Think of them as infant formula, special supplements, and the daily multi-vitamins.  Of importance is the numbers on each container, shown here (L-R) as 5-1-1, 0-5-4, 4-4-4 and 3-4-3.  These are percentages of the following:

Nitrogen (N) -Phosphorus (P) -Potassium (K)

So for example, the Fish Fertilizer on the left contains 5% Nitrogen, 1% Phosphorus, and 1% Potassium.  The ratios are important depending on the situation:

Nitrogen (N):  This gives your plants that lush green foliage.  If you've got pale, spindly tomato plants, they could be hungry for nitrogen.  Be careful, though, because too much nitrogen will cause the plant to produce leaves and no tomatoes. 

Phosphorus (P):  The middle number helps your plants set good roots, and also gives them a boost when they begin to flower and set fruit.  Either the Happy Frog or Down To Earth 4-4-4 are good choices to add to your soil at planting time to encourage good root growth and get them off to a healthy start.

Potassium (K):  The last number, potassium, is also needed when plants are flowering and setting fruit.  But Potassium is also important for continual growth throughout the season and to keep them free of disease.

My Fertilizer Time-Table

At Planting Time:  Both the Happy Frog and Down To Earth Vegetable Garden are granular mixes that I work into the soil when I plant. If you're planting in raised beds or in the ground, you'll want to dig your hole deeper than you need it, toss a couple tablespoons in the bottom, incorporate it with some dirt then place your plant on top.  If you're planting in containers, you'll want to mix it throughout all the soil if the pot is on the small side, or follow the in-ground rules if you're planting in half-barrels.  You don't need both of these fertilizers.  Either one is sufficient to get your plants started off on the right foot.  And while these brands are my favorite, the important thing is finding a fertilizer where the N-P-K numbers are in roughly equal proportions.

Between Planting and Flowering:  If you're starting out with rich, organic soil that you've amended since the last growing season and then boosted with fertilizer at planting time, you probably don't need to fertilize again until the plants start to flower and fruit.  But if your plants don't seem to be taking off at all since you planted, I'd recommend periodic doses of Fish Emulsion, which I'll talk about below.

A warning!  Starts that won't grow could also mean that you've planted too early.  No matter when you put them in the ground, tomato plants will sit there stagnant until night time temperatures are well into the 50's and day temps are in the 70's.  And most nurseries put their plants out long before it's time to plant them.  So if you thought you'd get a jump-start but those days and nights are still chilly, you may have just planted too soon.  Wait until temps are optimal before boosting them with fertilizer.

When They've Started To Flower And Set Fruit:  I happen to love the Gringo Rasta.  You'll notice it has no nitrogen, so it won't encourage the plants to keep making more leaves.  Instead, it's heavier on the Phosphorus and Potassium to encourage bud growth, and will encourage good sized tomatoes as well.  I try to fertilize every two weeks, alternating between the Gringo Rasta and the Fish Emulsion.  I think the Gringo gives a continual boost to tomato flowering and production, but the Fish Emulsion also has very important trace minerals (calcium, magnesium, sulfur, chlorine, and sodium) that the plants need to stay healthy and fight disease. 

Both the Gingo Rasta and Fish Emulsion are to be mixed with water, so be sure to follow the container's measurements and instructions.  When watering, I typically give each plant somewhere between 1-2 gallons of fertilized water that I apply using a 2 gallon watering can.

The Importance of Water

Never--EVER--fertilize dry soil!  You will burn your plants.  Instead, make sure you've watered well and let it drain off for a bit before watering with liquid fertilizer or sprinkling granules around your plants.  I also sometimes give the plants an extra dose of plain water after, just to soak it deep into the soil.  I tend to think that's more important with dry fertilizer than liquid.

Organic vs Chemical

You'll notice my pantry of fertilizers are entirely organic.  You'll also notice that I use relatively low N-P-K numbers.  If you browse through garden aisles, you can find fertilizers in concentrations of 10-10-10 and higher.  So why not more of a good thing?

First, I'm not a MiracleGro hater.  I've got a box of it in my shed, and use it from time to time.  But I look at chemical vs organic fertilizers the same as I look at vitamins vs healthy eating.  It's best to get nutrients naturally, and organic fertilizers typically include many trace minerals you don't find in chemical fertilizers.  They also tend to be milder, so you run less risk of over-fertilizing and harming your plants.  Also, those fertilizers with high numbers are often designed for a special use, often when a soil test has been done and a specific amendment is needed.  For the average person growing a typical back yard vegetable garden, I prefer higher frequency of a milder, organic fertilizer.

Can't I Buy Just One?

Absolutely!  For many years, I only fed my tomatoes with Fish Emulsion Fertilizer, and if you only want one product, that's the one I'd choose.  Though I also like the Down To Earth products, a whole series of which you can find at Friedman Brothers and Harmony Farms.  They have one specifically for tomatoes, and I'm sure it would be good.   It is powdered granules, so you would water then sprinkle it around your plants then water again to get it soaked it.  I haven't tried it, but it would probably be my choice if tomatoes were all I'm growing. 

A Caveat On Containers

My schedule is based on plants grown in-ground, I heavily amend my soil between planting seasons, and I rotate my plants around so tomatoes aren't grown in the same spot two years in a row.  Most all this advice on fertilizing can be applied to container growing as well, the only difference being containers will need more frequent fertilizing.  If you're growing in pots or half-barrels, I'd recommend fertilizing weekly, and alternating between a 5-1-1 fish emulsion and something else where the ratio favors the (P) and (K), such as the Gringo Rasta that is 0-5-4.  Or go with the Down To Earth All Purpose pictured here:

There you have it!  You made it to the end!

Next Week I will be posting about pests and diseases and what you can do about them, so I hope you will come back.  In the meantime, please leave questions in the comments if you have any.  I'm glad to help!

Happy Gardening!