Greenhouse gardening tips for beginners

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Growing in greenhouses the basics you need to know

  • Choosing a greenhouse.
  • How much does a greenhouse cost.
  • Greenhouse gardening tips.
  • How do plants get pollinated in a greenhouse.
  • Correct temperature for a greenhouse.
  • Benefits from owning a greenhouse.
  • Selling your surplus produce

Things to think about before buying your first greenhouse: size, type, plastic or glass, aluminium or timber frame and accessories you will need.

A Greenhouse will probably be one of the most expensive things you buy for your garden, but if carefully selected and used properly it will pay for itself many times over and more importantly give you many years of enjoyment.

 

Types of Greenhouse

There are many different sizes and shapes of greenhouse at all sorts of prices from "free to collector" to commercial greenhouses costing thousands, from polythene poly tunnels to aluminium or timber construction, from lean-to greenhouse to apex greenhouse.

 

The two main greenhouse designs are:

  1. A lean-to greenhouse, Lean-to greenhouses are designed to lean against another building, usually your house. Good if you have limited space and the temperature will be more stable because the house wall prevents large temperature fluctuations you also get a heating benefit from the heat escaping through the wall from your home, but it does cut down the light entering the greenhouse depending if the long bit is facing north or south. 
  2. An apex greenhouse is freestanding and has an apex roof which lets in light from both sides and permits growing on both sides providing more room. 

Plastic or glass?  Plastic is cheaper, easier to fit, is not brittle and won't break when the kids wack it with a football, but glass lets more light in than plastic and the more light that gets into your greenhouse the better. If the people using the greenhouse are prone to tripping plastic is the best bet.

 

Greenhouses frames are made from two main materials aluminium and timber.

 

Which material is best? 

Aluminium frames are light weight, corrosion free, and require no maintenance. It is also cheaper than wood  but does not look as nice, it also heats up and cools down much faster. 

Wooden framed greenhouses need to be treated every few years to protect them from rot, but hold heat better.

 

What size greenhouse is best for me?

Economy of scale comes into play here, the larger the greenhouse, the less it will cost per square foot of growing space, so it is best to buy the largest greenhouse you can afford and have space for. Once you get hooked and taste the difference, you will have no difficulty in filling it! 

 

How much Work-space will I need?

Your greenhouse interior should allow room for moving around and potting plants. 

Have benches to suit your height, to low can cause a bad back, to high you will have to stretch.  

Potting benches can be designed to fold down to make more room when not being used they're usually slotted so soil and water can fall through. 

You've got to get in and out carrying pots and compost, so make sure the door opens onto a solid path.  

 

What greenhouse accessories will I need? 

Guttering to collect rainwater and store in a water butt. 

Staging and shelving with slatted surfaces for planting seed trays and potting up and doing other work in your greenhouse. The slatted surfaces are important as they let soil and water fall through and allow air to circulate more freely. 

Ventilation window. It is very important to have a vent fitted in the roof of the greenhouse for ventilation.

What does a new or used greenhouse cost to buy?

What should I pay for a new Aluminium greenhouse? 

There are a lot of companies selling greenhouses, so drive a hard bargain. If an opening vent isn't included in the price, ask for it to be included. As a general rule expect to pay around £500 for a good  6ft x 8ft aluminium greenhouse with a sliding door and vent, £400 for a 6ft x 6ft  greenhouse and around £280 for 4ft x 6ft greenhouses. Or place an add on this site and maybe get one for free.

 

How much will a new wooden greenhouse cost?

A 8ft x 6ft timber framed greenhouse will cost about £900 make sure it comes with a minimum 10 Years Anti Rot Guarantee and includes Integral wooden staging.

 

How much will a used greenhouse cost.

You should be able to pick-up a secondhand aluminium greenhouse for about £100 or even free to collect A secondhand timber framed greenhouse will cost about double depending on the condition.

Because aluminium doesn't deteriorate and if you can wait until one becomes available in your area,  consider buying (or if you are lucky get it free) a used greenhouse. 

There were quite a few small greenhouses offered free to collect, but if you can,  go for as large a size as you can fit into your garden, or find two smaller greenhouses and link them end to end to form one large greenhouse.

You will probably need to dismantle it and certainly put it back together, It is a nightmare job especially putting the glass clips in, but you will probably end up with the racking and greenhouse heater too.

 

It takes a good long day to put a secondhand greenhouse back together, and you might need another pair of hands to help replace missing or broken glass, but it is a cheap way to own a greenhouse.

 

Tip: If you are positioning the greenhouse backing on to a raised area or building, fit the door into the frame first. I forgot, and had to dismantle the greenhouse frame.

Top Tip: Take photographs before you dismantle the greenhouse, having photographs makes it a lot easier to put it back together.

 

 This time of the year we sometimes have secondhand greenhouses listed here.

How do greenhouse plants get pollinated

Greenhouse plants get pollinated in the same way as plants growing outside

Opening the doors of your greenhouse for ventilation allows bees and other Insects to fly in and do the pollination for you. It will also help pollination of plants like Sweetcorn that are wind pollinated.

 

However if you want to give nature a hand try these tips to pollinate your greenhouse plants.

 

  • Pollinating tomatoes yourself. A little tap on the tomato plant will encourage pollination. You can also just gently shake the Tomatoes plant or flower truss.
  • How can I assist pollination of Courgettes,  the pollen can be transferred with a cotton bud or you can cut off the male flower, remove petals and stick the bit into the female flower 
  • Assisting pollination of greenhouse grown Sweetcorn. Sweetcorn has male and female flowers, male flowers at the top looking  like grass seed heads, the fine hairy tassels lower down the plant is the female flower. You can encourage the male pollen to fall onto these tassels by tapping the plants when the pollen is forming.
  • How do I pollinate Sweet Peppers growing in a greenhouse? Sweet peppers can be polluted by gently putting your finger inside the flowers and gently moving it about the flowers.

 

Giving nature a hand pollinating greenhouse plants.

There is nothing wrong with giving nature a helping hand, but opening the doors of your greenhouse allowing bees and other Insects to fly in and do the pollination for you and letting the breeze pollinate plants like Sweetcorn is best.

 

What is the best place in my garden to site a greenhouse

Best position for a Greenhouse.

Choose a level bit of garden preferably out of the way of young children, your greenhouse should receive the maximum amount of winter sunlight available.

  

Things to consider when working out where to position your greenhouse.

  • Try to avoid shadows cast by building or trees to allow maximum sun through.
  • Have the long side of your greenhouse facing south to catch the maximum amount of light and sun in the spring, autumn and winter.
  • Plan it to work with your landscaping, a greenhouse in the middle of a lawn or kids play area might look odd.

What Fruit and Vegetables can I grow in a greenhouse?

You can grow almost any plants you want to in a greenhouse.

Greenhouse gardening is much the same as gardening in the open, just altering it a little to grow stuff under glass. Remember a greenhouse doesn't have to be a "hothouse" unless you are growing a tropical jungle. Plants actually do best in temperatures slightly lower and with a much higher humidity than in our houses. You can control the temperature in small greenhouse quite easily.

 

You can plant and grow all the plants and more that you would normally grow in an outside garden in a greenhouse.

Early planting in your greenhouse is a good way to make the most of fruit and vegetables you are growing to eat. They should be ready just as prices are still high in the shops. I have listed plants that can be grown through winter here.

Feeding and watering greenhouse produce.  

If you  have a compost heap a mixture of one part compost, one part good topsoil from your garden, and one part sharp sand, and a little lime is the optimal soil for use in a greenhouse, particularly for growing tomatoes. If you don't have a 

compost heap  bags of potting soil from a local supplier are OK, but if you want to grow organically check the contents label. 

The only time you need to water is when the soil is dry. Over watering will kill your plants.

What is the optimum temperature for growing plants in a greenhouse.

Greenhouse Temperature tips.  

The more sun your greenhouse gets the more heat the greenhouse will produce. The ideal greenhouse temperature  (depending on what plants you want to grow)  is about  5 C.  

  • Place a thermometer in the shade near the middle of your greenhouse and check the temperature at different times during sunny and cloudy weather. 
  • If the temperature is higher and the plants you are growing need a range of about 5 C you will need to ventilate the greenhouse. The minimum temperature readings you record on a hot sunny day with doors and vents open will determine what plants you can grow. 
  • Key temperature for growing in a greenhouse. Two temperatures are key - the air temperature required in the greenhouse and the minimum outside temperature that your heating equipment must overcome. 
  • For most plants, a night temperature of 5 degrees C in the greenhouse is adequate. The general rule, however, is not to have a higher temperature than is necessary.
  • If you grow plants that require a higher temperature than is provided in the greenhouse, use a propagating case or a warmed bench with thermostatically controlled warming cables to warm the air surrounding those plants. This can be done at a fraction of the cost that would be necessary to heat the whole greenhouse to provide the same temperature. 

Greenhouse heating in autumn and Winter

How to keep greenhouse winter heating costs down, cheapest way to heat a greenhouse in winter, how to insulate a greenhouse in winter are answered on another page of my site   Winter greenhouse heating .

If you are looking for or are recycling a greenhouse visit this page  second hand greenhouses

Eight good reasons to own a greenhouse 

  1. Supply of vegetables out of season, 
  2. Growing cuttings of tender plants for next year.
  3. Protecting frost vulnerable plants from the Winter frosts, 
  4. Early start for tender plants started from seed.
  5. Getting in early with seedlings you may want to sell at a car boot sale.  
  6. Experimenting  with various plants as a hobby, or even  to develop new varieties.
  7. But most of all just the enjoyment of greenhouse gardening.
  8. Remember mistakes don't matter, its a learning curve.

 

 

 

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