In this Newsletter: Leggy tomato plants, grow pots, watering tips, the best way to feed tomatoes, when to start feeding tomatoes, the benefits of self watering planters.
As we approach the period of “final position planting” which is the end of May for growing tomatoes outside in the UK, or beginning of May in a greenhouse, there are a number of things we can do to “prepare the way” and optimise our efforts.
Leggy tomato plants
This is such a common problem, especially if seeds are sown a little too early.
It’s good to plant as deep as possible, removing the seed leaves and even the first true leaf branch if you can plant deep enough.
Roots will start to grow from the main stem, below soil, after about two weeks.
More about how to avoid and deal with leggy plants here.
It is difficult to plant deep if transplanting into a grow bag, although grow pots will provide extra depth of soil.
Grow pots are highly recommended for grow bags as they provide a separate inner ring for feeding and outer ring for watering. The feed doesn’t get washed away by plain water.
After the nutrients in the soil or potting compost have been used up by a plant, we usually add a general purpose food, or tomato food when watering.
Plain water will wash away the nutrients from around a plant’s roots!
So, if we feed once a fortnight and water every other day, our plants won’t be able to access the food they need on a regular basis.
The best way to feed
The ideal way to feed is to decrease the amount and increase the frequency – or in other words … little and often.
Some nutrients are depleted from the soil quicker than others as hungry plants require nitrogen (N) more than other nutrients in the early to middle stages. For this reason it is a good idea to continue with a balanced feed containing a good amount of nitrogen, rather than tomato feed with reduced nitrogen. We can feed with tomato food after the flowers begin to set fruit.
When to start feeding
If a grow bag has enough nutrients to feed three tomato plants for around five or six weeks, we won’t need to start feeding our toms until the first or second week of July, if we plant them at the end of May (outside).
Plants grown in a greenhouse will grow more quickly, owing to the more moderate and higher temperatures, so a grow bag will feed for a shorter period – around four or five weeks before the plants require feeding.
Of course it depend on the size of your grow bag … the average grow bag contains around 30 to 35 litres of soil. Super size grow bags contain 40 to 50 litres of soil, so we can add a week or two, to the timing above, before we start feeding when using the larger grow bags.
The most important consideration about feeding
In Holland they say: “Let the tomato plants tell you what they need” or something similar!
The point is … observation of a plant’s leaf colour will tell us if they are getting what they need and if there is a deficiency.
I talk to my plant’s regularly but I don’t expect them to answer back! 😉
Self watering planters (SWP’s)
The great thing about self watering planters is that they provide tomato plants with water and nutrients 24/7, whenever they want to drink and feed.
Also, it is possible to feed via the reservoir rather than adding all of the nutrients to the soil.
This helps avoid nutrient competition and excess in the soil. Some roots will grow down into the reservoir and take water and nutrients into a plant, avoiding the soil altogether!
It is possible to feed in three ways:
- Through the soil
- Through the reservoir
- Through the leaves – with a foliar spray
This flexibility of self watering planters, allows us to avoid a number of problems including nutrient lock up – when the excess of one nutrient blocks another from being absorbed through the roots.
Pots and grow bags
If you decide to use just basic pots or grow bags, it is a good idea to optimise them in some way.
Adding perlite, vermiculite, water gel crystals etc. helps to retain and hold more moisture in the soil – important on a hot day when plants are fruiting.
To avoid water logging, stick a few pencil holes through each end of a grow bag an inch above ground level.
If you poke holes in the sides of a grow bag, the water may flow out before the entire soil area is watered.
Grow bag trays are useful for making sure the soil is fully watered and great for standing pots in.
Air pots and fabric pots are very good for adding oxygen to the root zone (see respiration and tomato plants).
The soil in these pots tends to dry out a bit quicker, so sitting them in a tray with a watering valve is ideal, or watering them manually in a tray – from the bottom up – is good too.
If this is your first season growing tomatoes
If this is your first season growing tomatoes, you don’t need to have all these extra’s. In fact, it is a good idea to get some experience with the basic equipment, find out which varieties you like to grow and how you like to grow them.
It is about experimenting and learning along the way – finding out what works best for you, in your garden and in your part of the world.
Have a good week – I think wet weather is on the horizon for some of us!