Whether you purchased tomato seedlings from a nursery or grew them from a seed yourself, the moment of truth comes when you plant them out in the garden.
Will they make it? Are they going to be eaten by bugs? Am I going to have a bumper crop and be up to my eyeballs in juicy, red tomatoes?
As gardeners, there are so many variables that are out of our control: weather, pests, and disease.
It makes it all the more important for us to take control of the things we can to ensure a good growing year. I don’t know about you, but it’s just not a good season if the tomatoes don’t do well. Because really, who cares if you harvest three bushels of kale but lose your tomatoes to hornworms.
(Don’t hate me, I actually do like kale. It’s growing on me.)
My tomatoes are my babies.
So, when it’s time to plant my tomato seedlings out in the garden, they get the full spa treatment. I want to set them up to be impervious to as many environmental factors as I can.
Fertilizing is a big part of that.
As most of us who grow them can attest, tomatoes are heavy feeders. When it’s time to plant them in the garden, that’s the perfect time to give them a jumpstart with the nutrients they need to get established.
But it’s important that you’re giving them the right nutrients in the right amount.
If you don’t, then you’re setting yourself up for glorious, bushy tomato foliage without many tomatoes.
Don’t get me wrong, I’m one of those weirdos who loves the smell of tomato leaves, but I kind of prefer those leaves to be nestled around lots of tomatoes, too.
By fertilizing when we plant our seedlings in the garden, we’re encouraging strong roots, steady growth and a plant that’s got everything it needs to set blossoms. Grab your trowel and gloves, and let’s get those tomatoes off to a good start.
Start With the Basics
You should always start with good soil. When was the last time you had your soil tested? (She says, with a raised eyebrow and her hands on her hips.) If you’ve noticed an uptick in garden issues over the last couple of seasons, it’s a good idea to get your soil tested. This way, you can take care of any deficiencies or pH imbalances.
Tomatoes need well-draining soil that’s rich in organic matter.
Break up compacted soil and add some compost or well-rotted manure to it. Mix it in thoroughly before planting. Adding organic matter like this acts as a slow-release feed to replace nutrients.
It also improves soil texture, allowing it to drain quickly while still retaining moisture. All important things for keeping tomatoes happy.
A Once-a-Season Opportunity
Now that the soil is ready, we’re presented with a once-per-season opportunity – adding nutrients to the hole we’re planting in. Doing this when we plant our seedlings puts everything right where the roots can access it, and it’s less likely to be washed away by rain or subsequent watering.
Mycorrhizae need to be applied directly to the roots for it to be effective. (There are some blends that you can mix with water and apply by watering the root zone, but getting it right on the roots is the best way to apply mycorrhizae.) Now is the time to do it. You can read about how to do it here.
(Also, this is the mycorrhizae I use in my garden.)
Mycorrhizae are beneficial fungi that bond with the plant’s existing roots, making the whole root system massive. Using mycorrhizae with tomatoes is a great way to ensure your plants are more resilient to extreme heat. (Oh, hello, August!)
But you can also add things like bone meal, worm castings, crushed eggshells, Epsom salt or even a fish head.
Fertilizer
Now, we get to the fertilizer! You’ll want to add a tablespoon of a balanced organic fertilizer. Something with an NPK ratio of 5-5-5 or 10-10-10 is good. By adding a small amount of fertilizer, you’re giving your tomato seedlings a boost of nutrients to get them growing. Espoma’s Garden-tone is a great balanced fertilizer.
Avoid a Big No-No
While this is the perfect opportunity to put a few extra goodies into the ground right where your tomato seedling’s roots can reach them, there is one thing you want to avoid – burned roots.
When you’re dealing with tender seedlings, it’s important to make sure none of the things you’re putting in the planting hole come in undiluted direct contact with the roots. It will burn them, and you could end up losing the seedling.
Mix everything well into the soil at the bottom of the hole and ensure there is about 1” of soil between the seedling and everything you just mixed in. You can also mix these things in and then put the compost on top before you put the seedling in the ground. You don’t want bare roots in direct contact with fertilizer.
That being said, compost, worm castings, and mycorrhizae are all gentle enough that they will not burn roots if they are in direct contact.
Bury Your Tomato Seedling or Plant Them Sideways
Once you’ve mixed in a bit of fertilizer and your amendments, it’s time to plant your seedlings. But don’t just plop it in the hole. Bury it! Bury it deep!
Tomatoes can be buried, leaving half to a third of the plant above the soil.
While this sounds counterintuitive, it’s one of the best ways to protect your plants against drought.
The portion of the stem that’s below the soil will put out roots, making for a vast root system. The bigger the root system, the better off your tomato will be when the rain stops. The plant will push roots deeply into the soil, tapping into water further down in the ground during times of drought.
A large root system is also better at nutrient uptake, which means you get a healthier tomato plant that keeps cranking out more and more tomatoes.
The whole thing is pretty cool. For further instructions on how to handle burying indeterminate or determinate tomatoes, click here.
Don’t forget to water in your newly planted seedlings. They need a drink right away to help recover from transplant shock and to wet the soil amendments you added.
You’ll want to check your transplants and water them daily if the soil is dry and they look a little wilted. Until they start putting down more roots, they will need a watchful eye.
A Week Later
Now that your transplants have recovered and are settling in, it’s time for another gentle feed—this time, you want to water them well with a diluted liquid fertilizer. Half strength is good.
Fish emulsion is a good option, as are some seaweed fertilizers. But you want to make sure it’s balanced and has a decent NPK ratio. Many seaweed extracts don’t provide much in the way of usable nutrients. Rather, they provide trace minerals and plant growth hormones.
(You can read more about sorting through fact from the fiction about seaweed in the garden here.)
Likewise, you can use a granulated slow-release balanced fertilizer such as this one. Sprinkle half a tablespoon around the base of the plant and water in well.
One Thing You Want to Avoid
You’ll note that I’ve suggested a balanced fertilizer here rather than one that’s high in nitrogen. It used to be that we recommended nitrogen at the beginning of the season and then switching to a fertilizer that was higher in potassium and phosphorus once flowers began to set.
Using a fertilizer too high in nitrogen can backfire, leading to tomatoes with lots of foliage but few flowers.
In general, it’s best to always fertilize with a balanced fertilizer, one that has similar amounts of NPK. Using a blend that’s much higher in one nutrient than the other can end up creating deficiencies in your plants.
Plants are pretty smart at knowing what nutrients they need and when. As long as you continue to ensure that all three – nitrogen, phosphorus and potassium are readily available in the soil, you’ll be just fine.
And that’s that!
You’ve given your tomatoes the absolute best start to the season. They’ve got the nutrients they need to grow and start producing flowers. Before you know it, you’ll have tomatoes.
Get the famous Rural Sprout newsletter delivered to your inbox.
Join the 50,000+ gardeners who get timely gardening tutorials, tips and tasks delivered direct to their inbox.