As we are coming into the main planting and sowing time I thought I would cover soil and plant feed as they are such an important part of the garden. I know I covered feed in January but I have been doing some planting over the last few days and a couple of things occurred to me which you might find helpful.
My garden soil was awful when I started but I have got it into pretty good shape over a number of years. It has been built by adding large amounts of compost and seaweed but also by dressing with some beautiful organic manure supplied by my friend Clive Bright (to be accurate by Clive's cows rather than Clive himself). You might recognise the photo above from a recent mail which features some of his herd having their breakfast.
I usually add either seaweed, manure or both to some part of the garden depending on what I'm growing. This give me an all round fertile soil. I may need to add some amendments later on for hungry plants like tomatoes or courgettes but for the most part I can leave things as they are.
You may not have a ready supply of manure or access to seaweed so you will need to use some handier packaged products. We have a wide range of options to solve any problem all of which will be gentle on your soil. Just make sure you also add some bulky material every year, the best being your own home produced compost.
Liquid V's granular or bulky feeds
In general granular or bulky feeds like seaweed, manure or compost take longer to have an effect as they need to break down n the soil first. Liquid feeds, on the other hand, are readily available to your plants and will have an immediate effect.
It is a good idea to apply bulky organic feeds at any time of year to improve the long term health of your soil. If treating a specific issue or to give a plant a boost it will be more beneficial to use a liquid. Remember a liquid doesn't build the soil so they should always be used as a addition to your broader soil feeding regime.
The exceptions to this rule are container grown plants. They will always need direct feeding because of the limited root space available to them and the fact that they are growing in a simple growing medium like peat. Peat, coconut fiber or peat free compost has has very low nutrient levels so your plants will need a supplementary feed.
It is a good idea to start is with a home soil test which will show the levels of the major nutrients Nitrogen (N) Phosphorous (P) and Potassium (K). Potassium can also referred to as potash but it is the same thing. Wood ash from a fire or wood burning stove is also a good source of potash with ash from hard woods like beech or oak being best.There are also a range of micro nutrients but you will need to get a professional test for these to show up. Any micro nutrient deficiencies will show up in your plants with symptoms like yellowing between leaf veins (magnesium deficiency) or brown curds on cauliflower (boron deficiency) but most good garden soils will have sufficient quantities.
Plants need nitrogen for leaf growth, phosphorus for root growth, and potassium for fruit growth. All plants need all three, but leafy crops particularly need nitrogen, and fruit crops won't develop well without enough potassium. When you look at a bag of fertilizer you will see the NPK values displayed as 3 numbers.
For example an average tomato feed is labelled as 6:3:10. It has 6 nitrogen (N) for foliage, 2 phosphorous (P) for healthy roots and a high 10 potassium (K) to produce all the fruit we're hoping for. Cabbage, broccoli, chard and other leafy crops will benefit from a high nitrogen feed. Feeds high in nitrogen should be avoided on fruiting plants, however, as they will grow lots of lush foliage at the expense of the fruit.
The major NPK nutrients are in a refined, soluble form in chemical fertilizers which means they don't benefit the soil and are easily washed through into the ground water. NPK is also present in organic fertilizers but they tend to be in a slow release form, usually with some extra bulk which feeds the soil life as well as your plants. Where possible it is always better to use slow release organic fertilizers than artificial for this reason.
Use the minimum possible
With a direct feed, whether artificial or organic, you should use as little as you can. It does not follow that if some is good then more will be better as plants can only use a certain level of nutrients. The excess will be wasted or, worse, run off into water courses and cause algae growth and problems down the line.
Nitrogen will result in lush, leafy growth. Adding too much causes fast and weak growth which leaves your plants open to attack by pests or disease. In the case of fruiting plants excess nitrogen will also reduce fruit yield and quality.