When do you start feeding tomato seedlings, and how much/often?

[bobrarian]

First time posting a question. My tomato seedlings germinated about a week ago, and a few have grown their first true leaves.

I'm using a coco coir based starting mix, which I believe has no nutrients. Current plan is to use a water soluable fertilizer, and feed at 1/2 or 1/4 strength, once a week.

I plan to start feeding in a few days, when they're close to 2 weeks old. But I'd like to get your thoughts first, and learn what worked for you. Thanks!

Bobby

[Shule]

What kind of fertilizer is it? I mean, What brand/product, what's the NPK, and does it have any chloride salts in it? Chloride salts seem to burn plants more easily than sulfate or phosphate salts.

For those who don't know, NPK stands for Nitrogen-Phosphorus-Potassium. Those are often considered the most important fertilizer components. A 10-11-12 fertilizer has 10% nitrogen, 11% phosphorus, and 12% potassium. Other important fertilizer components include such as magnesium, zinc, iron, calcium, sulfur, and other trace minerals. If it doesn't say the NPK numbers directly, you can look at the percentages of each in the ingredients.

Diluting it sounds like a good idea until you eventually figure out how much you can use. I'm not sure about the frequency, though.

[mama_lor]

Usually if something is called starting mix, or seedling mix, it has little nutrients indeed, so it's time to start. I think traditionally coir had no nutrients, or almost none, because it was intended for hydro growers not for the casual person. Now, when it's more widespread, there's nothing stopping them adding it just like they add it to peat based mixes. I actually prefer a mix with a decent amount of nutrients, even for seedlings (something around 1.5g/l).

[bobrarian]

Good morning,

[mention]Shule[/mention] - I'll be using MG tomato food, which is 18-18-21. Not sure about chloride salts. I'll look at the ingredients on the label tonight. Now that I'm thinking about it, I may have to dilute even more. That sounds like a high NPK.

[mention]mama_lor[/mention] - Thanks for confirming. This is the first time using this starting mix. What do you use, if I may ask? I'll probably change it up next year.

Thanks,
Bobby

[Texgal]

I usually start fertilizing when the first true leaves appear. I have used a variety of fertilizers like miracle gro and Neptune’s harvest. No matter what fertilizer I used, I got the best results by going half or quarter strength and doing the feed on a regular schedule. I always adjust based on what I see the plants reacting to after feeding.

[MissS]

If I am using a seed starting mix, I start feeding the plants a diluted feed when they get their first true leaf. If I am using choir or DE which have not had any nutrients added, then I will pre-charge the medium before I sow the seeds with a diluted solution of my nutrient mix which is usually some blue stuff. I avoid using organics until my plants go into the ground because I have found that I get more fungal issues using organics indoors on young plants.

[mama_lor]

@mama_lor - Thanks for confirming. This is the first time using this starting mix. What do you use, if I may ask? I'll probably change it up next year.

I use klasmann deilmann or floraself flower mix (around 11 euro per 70l). Probably not available outside Europe. Here all the mixes have written on them what is inside in terms of npk, 'salt content' (which is really mostly npk) and pH. I assume yours should also. The more pro stuff have written an actual value while floraself, a cheap brand, just has a kinda broad range of values. With stuff like floraself the salt content is probably 2-3 g/l, and tomatoes love it, you pretty much don't need to fertilize but not all plants will tolerate that.

[Gardadore]

Once my seedlings emerge in coir and have their first leaves I add some worm castings. When I transplant I again mix more worm castings in and a small amount of a basic fertilizer like Espoma Biotone. A very diluted liquid fertilizer sounds fine as has been recommended as well.

[AZGardener]

I start feeding seedlings after they have their first pair of true leaves. I'd dilute MG down to about 5-5-5 or less. They don't need much at that stage and can burn pretty easily. HTH

[Sue_CT]

I don't feed at all. I start in little dixie cups and when they have their first or two sets of true leaves pot them up into solo cups in MG potting soil that has fertilizer in it. No feeding after that until they go into the ground. I don't start the seeds in anything bigger than a dixie cup, the kind they used to sell in a dispenser for the bathroom, very small cups, because if they do start to get a little leggy I can put them a little deeper into the solo cups when I pot them up. You will probably find almost as many ways of doing things as there are people on this forum, lol. You can try different ways, see how your plants react and find out what works best for you. For me, the less I have to do with them, the less I can mess up, lol. Also, I still work full time so getting them on auto pilot means they don't get neglected when I come home too tired or get too busy.

[bobrarian]

Thanks, everyone! Great to hear what you do. I think, with my setup and what I have on hand, that I will take the advice to dilute to a quarter strength, so roughly 5-5-5 or less. I will start tomorrow, and then keep an eye on them. Probably will wait 10 days to 2 weeks before feeding again, just to be safe.

[mention]MissS[/mention] - I really like your idea of pre-charging the starting mix before seeding. Will definitely do that next time!

[mention]Sue_CT[/mention] - Previously, I used mostly MG potting mix with a thin layer of starting mix on top. The roots would eventually reach down into the mix, and I didn't feed until they were a lot bigger.

Bobby