Tomato Plants

How to Feed Tomato Plants

Today on Grow It With Science I’m looking at some different ways to feed your tomatoes.

Whenever you go to the garden centre you’ve probably noticed that there’s millions of different plant foods available.

There’s bottles of liquid, boxes of powder buckets of chicken manure. But which ones are the best for feeding your tomatoes?

Today i’m going to compare two of the more popular shop bought options.

You’ve got your liquid tomato food and your liquid all-purpose plant food.

When we compare the contents of the bottles you’ll notice the tomato food is this dark orange kind of colour, all-purpose plant food is like a dark greeny brown sludge kind of colour.

Both of the plant foods that we’re testing today are what we call NPK fertilisers and that stands for nitrogen, phosphorus and kalium or potassium if you’re not Latin.

In this brand of tomato food we have 21 7 14 fertilizer.

So it’s potassium-rich plant food.

Compared to the all-purpose plant food which has seven percent nitrogen, three percent phosphorous pentoxide and five percent potassium oxide, so this is a nitrogen-rich fertiliser and obviously i’d recommend using the tomato food on your tomatoes.

All you have to do is check the directions on the back of the bottle and apply the mixture to your plants every 14 days at first increasing to every seven days as the plants grow bigger and start to develop fruit so with this brand we need to use 20mls in four and a half litres of water.

So if possible use rain water which I’ve just got in this bottle here, again i’ll cover the reasons why in another video, but if you don’t have rain water collected tap water will do just fine.

I’m going to be feeding the three tomato plants in this grow bag, which according to the instructions require four and a half litres.

Now i don’t want to give them that much at the moment because they’re only quite small, so i’m just going to give them 500mls each which is the contents of the sports bottle.

A quick little tip is to use a small drinks bottle with a sports cap for measuring how much each plant gets that means that each one of these bottles needs 2.2ml of food, so i’m going to round that down with two mils using this handy little syringe.

You get these in kids medicines like Calpol, absolutely worth keeping if you can get hold of one.

Just give it a shake and ready to go.

So you just want to let it soak into the soil around the stem, don’t touch the stem or the leaves with the liquid because it will damage the plants.

And then you just leave it and that’s it, so as you can see I’ve got a brand new grow bag here I’ve got three identical money maker tomato plants.

I actually managed to get these for half price because they were looking a bit worse for wear in B&Q’s reduced section.

So i’m just going to get these into the grow bag and then we’ll take it from there.

So, plant one, here on the left this is going to be fed with the specialised high potassium tomato feed so i’m just going to stick that in now now plant number two in the middle, this is going to be our control plant so this one’s just going to be getting plain water, no plant food at all.

Now with this being a grow bag it’s a bit of a sealed environment, so chances are the roots from this plant are going to spread outwards into the other plant sections and probably take a bit of both food from each so it’s going to be really interesting to see actually how this plant does in the middle and whether it does do that and you know, maybe it’ll do just as well as the others, so here it is plain water for you.

So then finally this is plant three, this one is just going to be getting the high nitrogen content all-purpose plant food that we saw earlier on in the video.
So let’s just mix this up.

So it is probably worth mentioning that with this being a new grow bag, they actually recommend seven liters of water goes into a new one, so as you’ll probably see there I’ve only actually put in three and a half litres, so while it might seem quite a lot that’s actually going in the plants might be getting too much water, they’re actually just going to soak that up and it’s just going to disperse out through the soil, and the actual plants themselves were pretty dry when i was putting them in so that shouldn’t be a problem.

Look out for the results of this experiment in the summer and we’ll be coming back and checking the quality and quantity of the fruit produced by these plants.

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