Many-faceted Career in Horticulture
Speaker: Steve Bradley
Date: 30th September
Steve introduced himself and described his career in horticulture. He is a broadcaster both on radio and TV, lectures on courses at the English Gardening School at Chelsea Physic Garden and writes for the sun in conjunction with Peter Seabrook. He has also authored 53 books on gardening with his wife, also a horticulturist.
His talk was basically about the soil, understanding it and how to manage it to improve our gardening.
He described the soil in terms of four layers, see table, and then posed the question “what is the soil like in your garden?”
Top Soil (From 1″ to 2ft in depth)
He told us to beware gardens in newly built properties as the builders take off the topsoil and mix it up (or sell it) so what they put back could be anything and need notbe native to the area. He advised against double digging as it mixes up the top soil with Lower layers and thus reduces fertility. The top 6 inches will be the most fertile so always put the manure and compost on the top and let the worms take it down.
He then went into the pH of the soil and how to test it and change it or noting it and growing plants to suit it. The pH varies from 1 to 14 and 6.5 is neutral in which the widest range of plants will grow.
Above 7 is alkali and roses carnations, apples and pears pink hydrangeas and the pea family will grow well to name but a few. Acid soil, less than 6.5, is good for camellias and rhododendrons, heathers and blue hydrangeas. White hydrangeas don’t mind the pH. Kits are available to test the pH but be careful not to use tap water as this will affect the result. Soil probes are not effective.
Steve recommended testing the top layer of soil and also down to where the plant roots grow as pH varies with depth. It is possible to test for nitrogen and potash levels and other nutrients too. Universal kits cost roughly £6/7. He advised that a wide range of fertilisers is not needed, he uses Growmore and a tomato feed and makes his own ericaceous treatment by mixing one tablespoon of vinegar into two gallons of water. This will reduce the PH from say 7.6 to 6.8.
Putting used tea bags around camellias is also effective. Compost and manure work by acting as catalysts and helping to release the nutrients already in the soil. Organic compost releases organic acids which also release the nutrients. Always put the fertilizer in the top layers for efficient nutrition.
Bonfire ash opens up the soil and mixing sand with clay soil improves the structure, cultivating the soil damages the structure which is why the “no dig” method is now advocated. Four inches of mulch is recommended for weed suppression and to conserve water, especially effective to spread it when the ground is cracked as it can penetrate lower down.
Steve then went on the talk about water profiles and different types of soil. The depth to which the water penetrates depends on the type of soil, with sandy soil a “carrot” shape profile emerges with time, i.e. it leaches away fast, and with a clay soil the profile is more like an “onion”, with wider and slower penetration.
To slow things down sandy soil needs some kind of “sponge” introduced. Steve didn’t recommend sprinkler systems, rather a slow running hose left in place for a long time before moving it on, “Leaky” hoses are ideal. He also advised us to water before rain to help it soak in and water only the plants themselves, not the surrounding soil.
Steve next told us that slow release fertilisers should be called controlled release fertilizers and explained their action and went on to tells us that the best active additive for compost bins is a small quantity of soil itself.
He finished his very interesting and informative talk with a tip about the latest snail/slug control made from wool shoddy. These pellets when spread over the soil swell up with moisture and create a blanket which immobilises the critters and also provides mulch and feeds the plants as well. It’s effectiveness last for about a year. It came over very clearly from Steve’s talk that “the answer lies in the soil!”