Noah Chase studied horticulture at the Eden Project in Cornwall, England. He now co-manages a family run nursery, Deelish Garden Centre in Skibbereen, specialising in rare, unusual and edible plants. His passion is sustainable gardening, useful plants and care of the environment
‘Feed your soil; not your plants’, a wise saying often used in organic gardening.
The reason for this is that once you have created a healthy, living soil, your plants are going to thrive. It’s the micro-organisms in the soil, and their complex relationships with each other and your plants that make nutrients available for growth. A teaspoon of healthy soil contains more microbes than the entire human population!
Traditionally at the start of each new growing season, gardeners top up the soil to ensure that the new crop will get the best start. For new gardeners, the choice can be overwhelming, and it’s hard to choose from the many options available.
Here are some of the common soil improvers gardeners use, with some pro’s and con’s of each:
Manure (horse, cow, sheep)
Well rotted manure from herbivores will greatly increase the amount of organic matter in the soil. This encourages earthworms and microbes, which help with soil structure and nutrient availability. These manures contain some nitrogen but are not overly ‘rich’. Manures from grass animals will always contain seeds, so be aware of potential weeds. It is best to compost manures before use; to help ‘cook’ seeds. If you can’t get your hands on well-rotted manure, Deelish Garden centre sells organic heat-treated bagged farmyard manure.
This manure packs the most ‘punch’ in regard to nutrient content, but it should be used with caution because of its strength. It provides very little organic matter but its nutrient content makes it great to use on hungry crops like potatoes, leafy greens and tomatoes. It is always best to compost poultry manure, and to use it sparingly around acid loving plants. Poultry manure used regularly will raise pH of soil. We recommend Using Greenvale, which is a mix of Pelletized poultry manure and seaweed dust.
Compost can be used as a soil improver, and is great for adding organic matter to the soil. Whether you make it yourself or buy a commercial product, it is one of the best ways to improve soil structure.
Compost is a fantastic way to recycle garden green waste, weeds, lawn clippings and food scraps, and prevent them going to landfill. However, nutrient content of compost varies wildly; depending on the source of ingredients.
A very popular product we stock is Soil Renew, it is a combination of organic plant material and microorganisms which create humus in the soil. It is in pellet form and just needs to be scattered on the surface of the soil. We find it works wonders on tired soil that need a lift for the growing season ahead. It also works very well on damaged soil, for example around new building sites, as a little will go a long way…three kilos of Soil Renew will produce as much organic matter as one tonne of farmyard manure!
Green manure is the name given to any crop, which is grown specifically to chop down and dig into the soil. It is a cheap and effective method for incorporating organic matter into your garden. Green manure crops can be plants like mustard/brassicas, rye, vetch, peas, lupins etc. but any quick growing, lush plant can be used. Cut them before they go to seed or you can end up with a weed problem. Roots and all can be left in the soil to decay. Green manure crops recycle nutrients from deeper in the soil back to the surface, when the plant decays back into the soil. Mustard, Tares and Ryegrass are great for spring sowing as they germinate at low temperatures. Over wintering green manures are a good idea for empty vegetable beds, as they stop weed growth, soil erosion and compaction and can even fix nitrogen in the soil.
Seaweed acts like a tonic for your soil. It will provide a diverse range of minerals and trace elements to the soil, and stimulate soil microbes to make nutrients available to the plants. It promotes beneficial soil fungi and bacteria, which all support healthy plant growth. We supply both dried seaweed (which takes longer to break down but releases over a longer time) and liquid seaweed (faster acting but needs to be applied every few weeks). If you can source fresh seaweed, this is best and can be used as a mulch around the base of plants.
Blood and Bone
A great source of nitrogen and some phosphorous, but little potassium. (Add about one part of sulphate of potash to four parts of blood and bone for a good, general purpose fertiliser for all plants.)
If you are lucky enough to have access to a worm farm, castings are brilliant to use in your garden. Castings are packed with beneficial microbes and concentrated trace elements. They have the ability to retain moisture in the soil. Use a small handful when you plant out seedlings to help get them off to a flying start. Worm juice can also be collected from the bottom of worm farms and used like liquid seaweed for great growing results. We now stock ‘living green’, which is an organic compost with worm castings, made in Ireland and is ideal for growing vegetables.
Often used as a mulch on top of the soil, straw will also decompose relatively quickly and add valuable organic material to the soil. Not particularly high in nutrients, but straw is often inexpensive and the organic material will improve both sandy and clay soil structures. Be aware straw (which is the lower part of the plant after the heads have been harvested) contains less seed than hay (which includes the seed head) but there will always be some seeds remaining – so watch for weeds. Like fresh bark mulch, straw will temporarily lock up nitrogen but will release it, as it breaks down.
If you have added a range of nutrients to your garden and are still concerned about the health and vigour of your plants, it is worth conducting a pH test on the soil. If your soil is either too acidic or too alkaline nutrients in the soil will be unavailable to plants, so you will need to add specific amendments to fix the problem. Add ground lime or wood ash (good on sandy soil) to raise the pH, add pine needles, coffee grounds, compost or manure to lower the pH.
So, as you can see, there are lots of ways to feed the soil, all that is left is to find which ones suits you. Remember, gardening doesn’t need to cost the earth.