Tomato feeding, watering, comfrey and other organic fertilisers

I just thought I would bump up this post from last year.

Tips on Watering Your Tomato Plants

One of the most important aspects of providing adequate care to your tomato plants is watering.   
Because people often feel lost about when and how much to water their tomato plants, I’ll give you some  tips that you can use to make sure that you are watering your tomatoes just about right.

All fertilisers contain at least one of the major plant foods that is:

Nitrogen (N)-for stem and leaf growth;
Phosphate (P)-for root growth
Potash (K)-for flower and fruit production

This is shown on packets or bottles of feed as the NPK ratio, but it can be misleading as it is quoted in different figures, but for tomatoes you basically need a 1.1.3 ratio or percentages of that. But the main thing is to have more Potash than Nitrogen. There are always other minor ratios of other chemicals added to most feeds, which the plant also requires, these are usually described as trace elements.

The compost used to raise your plants in should have enough fertiliser until you see the first bunches forming. Then to make it simple for the first few weeks just feed with half strength tomato feed. After that it will depend if you are growing in the soil or a growing medium in posts or bags.

The soil will have a reserve of nutrients so maybe feed once a week, growing mediums will need feeding more often.

The only time you might need a high nitrogen feed again is if your plants are loaded with fruit and the heads are thin, so require a foliar feed i.e., a flower feed, which is high in nitrogen.

As for organic feeds, nettle tea is not so good as it is very high in nitrogen, comfrey on the other hand is high in potash and has plenty of other elements that it has taken up from the soil deep down, as it has a deep root system. Seaweed again is high in potash.

This advice is based on getting a good production, I am sure people with a short season, do not always stick to this and still get good results.
At the end of the season, when you have stopped the head of the plant, you can then stop feeding.

A little added advice for the end of the season to help prevent splitting fruit is to leave the shoots on after you have stopped the head, these tend to take up any excess moisture. To be fair, I have not tried this but it was   recommended in the Gardener's World magazine.

Watering in the greenhouse
Plants put directly into the soil are far easier to water, as you have a large reserve of soil, so follow the tips on outdoor watering and you will not go far wrong. 
Far greater care has to be taken when watering pots or growbags, as you have little reserve to play with.

Growbags are best watered with a drip irrigation or very gently with a hose. You must soak all the compost first by making a small hole in the top of the bag and let it gently fill with water. Then leave it for a few hours to soak in. Then cut  three slits about two inches long either side of the grow bag, about an inch off the floor. This will allow the excess water to drain.  Do this a day or so before you plant your plants into the grow bag. Three plants per bag is the recommended amount, although some people like to stand their bags on end to give a greater reserve of compost, but then only put two plants in.
The idea is to keep the compost constantly moist, which means that if you squeeze it with your hand, then you should get water dripping out. If it drips out before squeezing, then it is too wet.
In ideal conditions with automatic watering,  you would water 3 or 4 times a day on hot days, but once a day will be OK, but make sure the bags are thoroughly wet i.e., the water should be dripping out of the drainage holes.

Home made drip irrigation system (thanks to Big Mally Grow Your Own Forum) You never know when something may come in handy. I had some tubing & adjustable connectors saved from my aquarium days as I hate to throw things away. Anyhoos, today was that handy day when I found myself a plastic box, drilled a hole in the side near the bottom, fastened the tubing & connectors & Bob's yer uncle, cheap irrigation for my toms. The beauty is that I can adjust each connector so that it drips just as I want it to.

Pic 1 = Box (obvious really..........)

 You could use an outside water butt as well.

Pic 2 = Setup

Pic 3 = Adjustable connectors............easy to get hold off from aquarium shops.

This is a big dilemma for many people, especially with plants raised in peat bags or containers. So a system like above is a really good solution unless you have someone who could come in and water your plants.
This a how BM managed to keep watering his tomatoes while away.

Quote from BM.
 I set up a gravity system and went on holiday for 2 weeks & the container was still half full. I have  changed the plastic box as I could not stop the first one leaking but as you can see the drip system seems to have worked.The toms may not be as tall as some but I'm pleased with the experiment so far. Please bear in mind that the drips are at approx 30 sec to 1 minute interval so it is not a continuous flow of water.

As you can see he came back to really healthy plants.
So it just goes to show that you do not need to spend a fortune to make up a simple watering system. As mine are all in the soil, I use a simple seep hose system connected to the hose, and for feeding I just use a watering can. However, I think in the future I will copy BM's system so that I can put my feed directly into the tank.

You can also purchase a bottomless large pot that sits on top of the grow bags, this has a rim around the base which you pour water into, that gradually soaks down. This gives you a greater reserve of compost, and makes watering easier with a hose.

Watering pots is similar to growbags and easier to water with a hose. Some people stand their pots on a gravel base enclosed in a tray. They then water the tray so that the pot soaks up the water. Or you could stand the pot just on soil. If you do water from the base, always make sure that the pot is sometimes watered from the top as the compost could dry out. A very good way to test if your pot is wet enough is to lift it gently and feel how heavy it is. However, I would not do this later in the season, as you will disturb any roots that have grown through the base of the pot.

Watering outdoor tomatoes

Never hurry while watering the plant. A sprinkler or a drip hose is a much more effective way of irrigating your plants since they provide the water in a slow and easy way.
Most people don’t know how often to water the plants. Now there are a lot of aspects that will help you decide. If the weather is too hot, you may need to water your tomato plants more often than when it‘s relatively cooler. However, watering them once every 2-3 days during summer is a good idea. When it is raining, you don’t need to water it so often. If the weather is cold, watering them about once a week is just fine.
The thing to remember is  that there should be enough water, although you need to be careful that there isn’t so much that it hinders the growth of the fruits. Lack of water will stunt the growth of the plants and you may end up with  blossom end-rot. So the blossom end of the fruit will appear as soaked with water and you will not get a decent fruit.
On the other hand, over watering is a problem many home gardeners face. It can result in lush foliage with cool and moist soil, but fruits are less in number and ripen slowly. Furthermore, if your soil is too wet when there is too much water after rain, you make the plants susceptible to disease. Excessive water has been known to destroy the entire crop of tomatoes. So, make sure you don’t over water as well.
Make sure that tomato watering is done early in the morning. This helps in hydrating your plants before the sun gets out and the plant begins to produce the necessary energy to make it grow. Avoid late afternoons or early evenings.
Mulch is very effective in preserving the moisture since it slows down evaporation. So, if you are finding it difficult to keep the soil moist or you live in a place that has an extremely warm climate, using mulch could come in very handy.
Also, remember that the root is where the water is required the most. So make sure the water is absorbed by the roots. Watering from above on the leaves of the plant may cause pests and diseases and isn’t effective in improving the growth of the plants either.
Some people prefer using an automatic watering system. Nothing wrong with that, but if you water your plants on your own, you are more likely to notice any problems on time. So try and spend some time watering your plants on your own, so that you can act immediately in case of any pest infestations or diseases. Besides, there is a risk of providing too much or too little water also.

Organic feeds like Comfrey, will save you money and some would say an even better tasting crop. Comfrey is a dynamic accumulator which extracts the nutrients in the soil and can then be used as a fertiliser. It's root system can grow up to 10 feet down to extract nutrients from places which other plants cannot reach. Other dynamic accumulators include, Borage, Bracken, Clovers, Stinging Nettles, and Yarrow.

To use Comfrey as a fertiliser there are several options. Firstly, they can be used straight from the plant as a lining for trenches or as a simple mulch, they can also be mixed with water and used as a liquid manure, or they can be incorporated into other composts. My favourite method is to cut the leaves and place them in a large water butt, with no water. The leaves will break down quickly and produce a black (very smelly) liquid, which can be diluted (10:1) with water and applied to crops.

The basic rules are to use confrey feed on plants with flowers or fruit, as it contains lots of potasium and nettle feed for leafy plants which contains mostly nitrogen.

To order Comfrey on line click here

This link will tell you all you need to know about COMFREY

This link will show you how to make other ORGANIC FERTILISERS

These links are to GYO Forum discussions on Comfrey, which should answer other question that you might have. There are a number of people that post on there who have years of practical experience of using Comfrey.


  1. what a great article. love your blog! keep doing a good job. take lots of your recommendation to my attention and i will try it. thanks!

  2. Well I am sure any of my readers in Israel will know where to go for some good irrigation eqipement now!
    Glad you like the blog.

  3. That is going to be very helpful for the growth of the tomatoes.vegetation that is grown with organic fertilizers will healthier and also more beneficial for the soil as it will stop the pollution.

  4. Tomato feeding, watering, comfrey and other organic fertilisers. I just thought I would bump up this post from last year. Tips on Watering Your.

    Automated Feed Pump for Drains Lines

  5. Answers my question on Comfrey, the high Potash content sounds good & may well explain what has gone wrong in the past. Many thanks, Tone from Devon

  6. Glad I could point you in the right direction Tone


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