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  • Writer's pictureGraham Tapp

Baldock Gardens march 2019

An often asked question I get, perhaps weekly, is can you tell me how to get more produce from my raised beds? The answer is usually more difficult than they would imagine. I will often ask them to sit down with me while I ask them some questions; sometimes we will determine between us that their beds are highly inefficient. Some gardeners I speak to are spot on in many details and ideas and will not be able to increase production without diminishing a return on investment, some will have to work a bit harder, why will become evident as we progress. Sometimes we discover that the growing media is usually ordinary garden soil and used over and over every year, sometimes its compost but the wrong type and again used many times. Most peoples expectations of a raised bed are so much more than it can deliver, an essential question for the amateur is why do you want to use raised beds rather than the soil they sit on? Most people can't answer or will give all sorts of reasons, unless you are unable to reach down to your soil or it is in an irreparable state may be contaminated, you will always get the best and cost-effective results from planting directly into the ground. Sometimes I am told that the person just wants raised beds and that's a good enough reason, we will then discuss the basics of the particular choice of crop, it's needs, rotations, nutrition, water requirements etc. Each plant will need a very different environment, but what they all need is light, sunlight. Sunlight is the one resource we cannot turn up, increase the supply or the intensity, we can reduce it by shading with netting, and we have to do that quite often especially in greenhouses. Because plants need sunlight to convert the nutrition we give them through photosynthesis, it is evident then that trying to push up crop returns by an increase in fertilisers or by early planting and late harvesting will not work unless you have vast knowledge on varieties or on-demand feeding, Ph and of course pest and disease control. To get maximum harvest weight from every square metre of your raised beds, you need to be someone with lots of time on your hands and great skill, well beyond that available to the average gardener. Raised beds then, will not grow anything with superior quality, better flavour and will give no increase in health benefits for you, what you will find is that it will cost you a lot of money and time compared to growing directly into the soil you have in the garden or your allotment. If you are a learner, you are best to stick with growing directly into the ground you have, leave the expense until later. Remember that a poor gardener is a poor gardener, an average gardener is an average gardener, a good gardener is a good gardener, and a professional gardener is a professional gardener. You won't jump a skill level by putting expensive wooden sides around bits of your patch, the only way you get better is putting in the time hard work and learning. Now let's step back a bit and look at nutrition, this will be the fertilisers that are available you can use all sorts of soil conditioners, manures straits, compounds and foliar feeds. Soil conditioners do just what it says on the tin, in our case bag, and are very important if you are working with clay soils or soil that has become compacted or exhausted through overuse. The medium you intend to grow your plants in needs to be open and friable, if you take a hand full and squeeze it into a ball you should be able to crumble it easily into small pieces but not dust, generally with the medium being too dry and dusty you will need to add water before testing for friability. The simple way to check for correct moisture is to wrap some newspaper around a finger push it into the soil count to four and pull it out if it comes out wet then it's too wet. If it comes out as it went in it is too dry, the paper should come out mottled or damp. When the moisture is correct, and you are unable to get the ball to break up, you will need to add a sandy/gritty soil conditioner. If it falls apart without being able to stick together, then you need a high organic content soil conditioner, in this context "organic" means high in recycled plant material (Humus) not what is nowadays used to describe a no chemical regime. Your soil or growing medium should have small spaces within it known as AFP air-filled porosity essential for gas exchange and also the ability of the soil to hold water which will also contain dissolved nutrients. If it's over wet, then there will be no air/oxygen, if dry then no water and so no dissolved nutrients. Ph of the soil is critical for what you feed your plants with, allowing it to be available to them. Very important for plants that are Ericacious they need a low Ph, they are not suitable to grow around here as our soils are chalk based with very high Ph. Being able to grow Ericaceous plants would be one reason we would use raised beds or even sunken beds with a membrane essential here in North Herts. Nutrients are supplied in various ways and could be liquid or dry, powdered or granular. It now gets more complicated. You can purchase straits or compounds; straits are a single type of fertiliser, for instance, Nitrogen, Phosphate, Potassium, Magnesium etc. A compound would be a mixture of any or all of them. You will most likely see the makeup expressed as units or %, for instance, growmore is a 7-7-7 a balanced general purpose fertiliser Fertiliser recommendations for growing individual crops can be found in many specialist books or online if you are not sure or don't understand, please call into our garden centre and ask for me and I will explain. There is a lot more to this, and I have run out of space on the page, so I will explain a bit more next time, in the meantime get planning and planting but don't expect miracles the first time. Happy gardening cheers Graham.

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