Greenhouse Gardening E-Book

Jonathan Edwards

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2011

Beschreibung

The greenhouse opens up a new dimension to gardening; making tropical conditions, a temperate room or even an alpine house a possibility. This practical guide adopts a simple and logical approach to what to do and when for the best results. Routine tasks as well as new ideas are included in any easy-to-follow monthly calendar of progress in the greenhouse.

Leseprobe

Greenhouse Gardening

Step by Step to Growing Success

Jonathan Edwards

First published in 1988 by The Crowood Press Ltd, Ramsbury, Marlborough, Wiltshire, SN8 2HR

www.crowood.com

This e-book edition first published in 2011

© The Crowood Press 1988, 1991 and 1996

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

ISBN 978 1 84797 359 7

Dedication

To Mum and Dad.

Picture Credits

All photographs by Dave Pike except for the step-by-step pictures on the following pages by Dr EJM Evesham: 31, 32, 34, 35, 36, 37, 66, 67, 84, 92, 93 and 97.

All colour artwork by Claire Upsdale-Jones.

Contents

Introduction

1 Choosing a Greenhouse

2 Siting a Greenhouse

3 Greenhouse Equipment

4 Compost and Containers

5 Propagation

6 Spring

7 Summer

8 Autumn

9 Winter

10 Pests and Diseases

Index

Introduction

Whatever your experience or expertise, a greenhouse offers the chance to extend your gardening activities. You can use it to help save money by raising bedding and vegetables from seed every year, as well as propagating other plants to fill garden beds and borders. If you can install a reliable source of heat, there’s an opportunity to get off to an earlier start and grow crops that require a long growing season. In colder climes, a heated greenhouse enables you to grow crops that would not thrive outside, and in a milder climate the options are almost limitless. For many gardeners, though, a greenhouse is a retreat where they can escape the worst of the weather and still carry on with their favourite hobby.

No matter what your reasons are for buying a greenhouse, you will get a lot more from it if you plan carefully and keep a watchful eye on the plants you are growing. This book will help you choose the right greenhouse and enjoy growing success for years to come.

Mini-rose ‘Sunblaze’.

CHAPTER 2

Siting a Greenhouse

It doesn’t matter how good your greenhouse is or how green your fingers, if your greenhouse is sited in the wrong place (for instance, under overhanging trees) results will be disappointing.

LIGHT

Good light is essential – preferably on an open site well away from fences, buildings and overhanging greenery. If the available light is reduced, then the crop yields will be diminished. Furthermore, in autumn deciduous trees create an additional problem with falling leaves blocking the gutters and drainpipes. Trees also harbour pests and diseases or even spatter your house with a sticky exudate that is soon colonized by algae and moulds.

SHELTER

Although the best light may well be on top of a nearby mountain or hill this is probably the last place you want to site your greenhouse. The exposure, if not destructive, would certainly curtail crop yields and increase heating costs considerably! In effect a balance is needed: away from shade, but sheltered from the worst weather.

FROST POCKETS

Frost pockets can usually be found lurking behind walls or dense evergreen hedges at the bottom of a slope. They are in effect trapped cold air that has run down the slope and been caught by the solid barrier. Don’t erect your greenhouse in such a position.

MAINS SERVICES

Supplying water and electricity services to a greenhouse can add considerably to its initial cost. Although desirable, it is not essential to have either. However, it is worth noting that a greenhouse without these services will have limited use. After all, the easier a job the far more likely it is to get done.

If you want these services then they should be a prime consideration when you are deciding on a site since the further a greenhouse is from the mains supply the more costly the installation.

ACCESS

Just as a new town needs to have good road links to prosper, so a new greenhouse needs weather-proof pathways and be conveniently sited. If it is at the bottom of the garden at the end of a long, narrow, muddy path then it will, at best, become a fair-weather hobby.

Best of all, site your greenhouse a few yards from the back door with a clean, even paved access path to it and right around it.

ORIENTATION

Much confusing advice is available about which way to point a greenhouse for the best results. For general-purpose growing the apex of the greenhouse should run north-south, but if you intend cultivating winter crops that need a lot of light then it is better to position it with the apex running east-west. This argument, though, tends to be rather academic since most small gardens do not provide enough space to afford the luxury of choosing direction. The difference it makes is rather marginal anyway, except with a particularly long, narrow greenhouse.

PUTTING UP AN ALUMINIUM GREENHOUSE STEP-BY-STEP

An aluminium greenhouse is made from a surprising number of components. Before you set about trying to put the structure together, it is worth checking them off against the delivery note supplied by the manufacturer. This will not only make sure you have all the bits you need, but will help you to familiarize yourself with the different components.

1. Check that all the ‘pre-drilled’ holes have been completed and are in the right place.

2. Check aluminium bars are not twisted or damaged.

3. Lightly oil bolts before you start to prevent the nuts sticking.

4 If your greenhouse is supplied with a base, construct this section first making sure each corner is perfectly square (see ‘Foundations’ opposite).

5. In an open space (e.g. a lawn) assemble each side and end and then both roof sections. Then take each section to the prepared site.

6. Bolt together the various sections according to the manufacturer’s instructions. It’s worth having a drill handy just in case a pre-drilled hole isn’t in the right place or hasn’t been finished properly.

7. Tighten bolts evenly over the greenhouse until it is firm and rigid.

8. Anchor the frame to the base or where no base is being used, concrete in ground anchors according to the manufacturer’s instructions.

9. Assemble the door and vents, then attach them to the frame.

10. Glaze the frame from the bottom up on a calm dry day to reduce the risk of breakages.

PUTTING UP A WOODEN GREENHOUSE

This is relatively simple since the sections come ready-assembled. All you need to do is lay the base as for an aluminium greenhouse, then bolt together the sides and ends, fit the ridge bar and roof spars or roof sections and glaze the structure. Some models even come ready glazed.

FOUNDATIONS

Laying good foundations makes greenhouse construction a simple job. Many models are available with ready-made bases (sometimes as an optional extra) that consist of pre-cast concrete kerbstones which fit accurately together to form a rectangle. These usually require setting in the ground to a depth of a couple of inches or so. Check that the corners are exactly square using a 3, 4, 5, triangle before firming in the soil. (A triangle of sides 3, 4, and 5 units (inches, metres, etc.) gives an accurate 90-degree angle.) Also, on exposed sites, further anchorage may be necessary, so consult your dealer.

DIY FOUNDATIONS

You can make your own foundations for a greenhouse by digging a trench 8in (20cm) deep and wide, and filling it with concrete. In addition, you could raise the greenhouse slightly by laying one or two courses of bricks on the concrete to match the dimensions of the greenhouse. More than this will make access to the greenhouse difficult.

On exposed sites, further anchorage may be necessary.

PUTTING UP A POLYTHENE TUNNEL STEP-BY-STEP

This is quite different from putting up a greenhouse and probably less fiddly, although you will need at least two people (preferably four) when putting on the polythene sheet.

1. Before you start, check through the delivery note to make sure you have all the parts.

2. Mark out and level the site, clear weeds and any other debris.

3. Position pairs of foundation tubes (short pieces of metal tubing that hold the ends of the hoops) so that the sides of the tunnel are straight and the ends at right angles. They will need hammering into firm earth for small tunnels and setting in concrete for larger tunnels.

4. Put together the hoops and slot into the foundation tubes, then fit the corner braces. Tighten all bolts so the frame is rigid.

5. Dig out a trench right round the tunnel (apart from the doorway) to bury the ends of the polythene sheet. A trench 6in (15cm) wide and 6–10in (15–25cm) deep should be sufficient.

6. Assemble the door frame and attach to the end hoop, making sure it is square so the doors fit snugly.

7. Wipe the hoops then put on anti hot-spot tape to all outside edges that would come into contact with the polythene.

8. On a warm, calm day pull the polythene sheet over the frame. Bury one side in the trench already excavated and stretch the sheet evenly over the hoops. The polythene must be kept taught while it is buried in the trench running along the other side. The warmer the day the tighter the polythene fit.

9. Pleat the ends neatly so that they can be attached to the door frame using battens – again pull the polythene as taught as you possibly can before hammering on the battens. Trim any surplus polythene from around the door frame and fit the door.

10. Pull the polythene taught at each end by burying it in the prepared trenches.

GLAZING

Always glaze your greenhouse after erection. Many models come with glass cut to size and ready to be slotted into position, but others need glazing. Use horticultural quality glass (3mm or 24oz panes).

Aluminium greenhouses are usually easy to glaze using plastic or rubber bedding strips set in the glazing bars. All you need to do is position the glass and snap in a few glazing clips and the job is done. Wooden structures can be more of a problem, involving the traditional and rather messy business of setting glass on putty and holding with glazing sprigs.

With all types of glazing where panes overlap, start at the bottom and work upwards, otherwise the overlaps won’t shed water, but collect it!

Using a 3, 4, 5 triangle to check that the corners of the base are exactly square.

CHAPTER 3

Greenhouse Equipment

HEATING

It is surprising that so few gardeners heat their greenhouses. If you don’t provide some form of heat, your growing season will be mid-spring to mid-autumn (several weeks shorter in the north) and the range of crops will also be reduced. The three main reasons often quoted why gardeners are put off heating their greenhouse are that it costs a fortune, heaters need constant supervision and there isn’t anything to grow in winter anyway. None of these arguments are true if you take care to select the right heater for your situation and choose the right crops to grow. First of all, make sure your greenhouse is in a fit state to be heated. That is, it is not exposed to the prevailing winds and is fairly air-tight once the vents and doors are closed. Then cut down the volume of air to be heated to the minimum, by partitioning off an area using insulating bubble polythene. Select a heater with a thermostatic control so that it will turn on and off automatically to keep the greenhouse at the correct temperature. Remember an extra 9°F (5°C) can almost double the heating costs.

If you can keep your greenhouse frost free, you’ll be able to overwinter tender perennials such as geraniums and fuchsias as well as overwinter early bedding such as antirrhinums. By maintaining a temperature of 45°F (7°C), however, you would be able to grow a wide range of crops all year round.

Heating a Lean-to Greenhouse

You may be able to heat a lean-to greenhouse by extending your household central heating system. By fitting an independent thermostat on radiators in the lean-to you will be able to keep the greenhouse at the right temperature.

CHOOSING THE RIGHT HEATER

These days, you have the choice between electric fan heaters, bottled gas heaters, natural gas heaters or paraffin heaters. There are solid fuel heaters too, but they are not really a viable option for a small greenhouse. The different types of heaters have distinct advantages and disadvantages so consider the following before you choose:

Small paraffin heaters are ideal for the amateur greenhouse.

Electric

Pros

Clean and small.

Thermostatically controlled so will operate automatically.

Have a fan that moves the air around and keeps the air temperature even throughout the greenhouse.

Cons

Expensive to install if you don’t have a mains supply to your greenhouse already.

Paraffin

Pros

Cheap to buy.

No installation costs.

Cons

Needs constant monitoring to maintain correct temperature.

Needs filling regularly with fuel.

Produces water vapour that may encourage diseases.

Greenhouse needs ventilating.

HOW TO AVOID BIG HEATING BILLS

Don’t heat your greenhouse to a higher temperature than you need.

Keep the volume of air being heated to a minimum by sectioning off part of your greenhouse. If that section is in the middle of the greenhouse or at least not on the side of prevailing wind, you will reduce your bills further.

Insulate the area being heated. Bubble polythene insulation material can be recouped in one season if you live in a cold area or heat your greenhouse to 45°F (7°C).

Draught-proof your greenhouse.

Start heating after the coldest weather is over by avoiding early sowings.

Install soil-warming cables or buy a heated propagator to avoid heating your greenhouse at all.

Bottled Propane Gas

Pros

Clean.

Thermostatically controlled so will operate automatically.

Cons

Expensive to buy.

Produces water vapour that may encourage diseases.

Greenhouse needs ventilating.

Natural Gas

Pros

Clean and small.

Thermostatically controlled so will operate automatically.

Cons

Can be expensive to install if you do not have a mains gas supply to your greenhouse already in place.

Produces water vapour that may encourage diseases.

Greenhouse needs ventilating.

Safety First

Always stand your heater on a surface that is firm and level where it cannot be accidentally knocked over.

Always keep the area around a heater clear, especially of flammable materials such as bubble polythene.

Always keep the door shut and preferably locked as well to keep children out of a heated greenhouse.

Always use an RCD with an electric heater.

Always use premium grade paraffin.

Always turn off a paraffin heater before moving it.