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A greenhouse looks simple until you stand in front of one and wonder where on earth to start. But no shame in that! Everyone has that early wobble moment. The good news is that you learn as you go, and that’s what this guide is here for.
How to Start a Greenhouse
Everyone has to start somewhere, and for a greenhouse that means getting the basics right.
The type of greenhouse to choose
Since you’re starting, keep it simple. A small plastic or polycarbonate greenhouse does the job. They’re light, easy to put up, and hold heat well.
Glass looks nice, but it’s heavy and expensive, so only go for that if you want a permanent setup. A wooden greenhouse is also an option. It’s traditional, lasts well if treated, and gives a bit more insulation, though it needs a little more care.
Size matters, but don’t overthink it
Big doesn’t always mean better. You want to move around comfortably and reach all your plants. Leave space for a shelf or table to make planting, watering, and harvesting much simpler. A small, organised greenhouse beats a big, empty one every time.
Get more tips here: How to Maximise Space in a Small Greenhouse
Air and ventilation
This one catches most beginners out. Mild days can make the greenhouse feel like an oven. Make sure there are vents you can open or a door that swings wide.
Automatic vent openers help, but a roof vent works fine if you check it every day. Leave space between plants so air can move around.
More tips can be found here: What to Do if Your Greenhouse is Too Hot
Getting plants underway
We know how overwhelming it can get with all the plant options out there. But the trick that always works is starting small and going for forgiving varieties.
Examples are lettuce, radishes, and cherry tomatoes, which are all classic beginner choices. Herbs like basil, parsley, or coriander are also great. They’re low-maintenance, and you can snip them straight into meals. And as much as possible, avoid aubergines or peppers, as they take longer and need more attention.
Another tip is to stagger sowing. Don’t plant everything at once, and start with a handful of seeds every couple of weeks instead. Just take it slow and stick with what you can manage first. After learning the basics of watering and light, try adding a few new crops.
Greenhouse Tips and Tricks
Apart from the tips above, sticking to a few routines keeps your greenhouse manageable and your plants happy.
Look over your plants every morning
Take a walk through your greenhouse each morning to see what needs doing first thing. You might spot some plants that look droopy or thirsty, and you can water them or move them to a different spot. If it’s getting warm, this is the best time to open the vents or doors to ventilate.
As you’re looking around, check for signs of pests, like tiny holes in leaves or sticky residue. Remove anything that looks suspicious and unhealthy before it spreads.
Keep an eye on your trays and pots, too. Don’t let water sit in the bottom, but don’t let soil dry out completely either.
Water your plants the right way
Keep a simple routine for watering. Most plants do better with small amounts regularly than with a single soaking.
Use a watering can with a fine rose, which helps you water without disturbing seedlings. For the little ones, water from the side rather than straight on top. After a while, you’ll notice which plants drink fastest and which trays dry out at different rates.
For big, established plants in large pots or in the ground, you’ll sometimes water more deeply but slightly less often.
Tip: Check the soil before watering. If it’s still damp, skip it for the day.
Learn more: How Often Should You Water Greenhouse Plants
Keep an eye on the greenhouse temperature
A greenhouse heats up fast. Try to keep it between 18 and 24°C in the day, and let it drop a bit at night, around 12 to 15°C.
Some areas can get hotter than others; move plants around if needed. If the sun is strong, put some shade over the hottest spots, such as an old sheet, cardboard, or shade cloth. Open doors or vents if it feels stuffy, and keep a small thermometer to monitor the temperature.
On cooler days, close doors and vents. You may also cover walls with bubble wrap when it gets cold at night to hold in the heat.
What to Grow in a Greenhouse for Beginners
Earlier, we touched on a few beginner-friendly options, but here we’ll go into a bit more detail.
- Plant bush varieties of tomatoes in large pots or growbags. Space them apart and use stakes or small cages to support growth. Water at the base rather than over the leaves to avoid disease. Read on for more details: How to Grow Tomatoes in a Greenhouse
- Sow lettuce and leafy greens seeds in shallow trays or pots. Start with a few seeds and thin out any crowded seedlings as they grow. Harvest leaves from the outside first to keep the plant producing.
- Use small pots or a dedicated herb tray for basil, parsley, and coriander. Snip your herbs often instead of letting them flower to keep them bushy. Keep the soil a bit damp, but not soaking.
- Sow radishes, rocket, and baby spinach in rows for fast results. Harvest the young leaves as needed to keep the plants producing. Then add small batches of seeds every week or two, so there’s always something coming up.
- Grow chillies indoors or in small pots, then transfer once they have a couple of true leaves. Give them the most sun-exposed spot possible, as they like it warmer than lettuce or spinach. Water consistently, but let the top layer of soil dry out between watering.
For something a little different, strawberries are surprisingly easy in a greenhouse. Use hanging baskets or raised containers and keep the soil moist. Bush beans also do well in larger pots and can give a quick crop if they’re kept warm and watered regularly.
Even with these beginner-friendly plants, there are ways to increase greenhouse food growth.
How to Keep a Greenhouse Warm
During the day, let as much sun in as possible – and remember, clean windows and panels make a big difference. Wipe them down to let the light through. And when night comes, and it starts to get chilly, bubble wrap along the walls or roof helps hold the warmth. Shut doors and vents in the evening, and raise pots or trays off the floor if it’s cold.
Covering young plants with a fleece also keeps them from getting cold. Some people also use bricks or water barrels inside. Put a few in sunny spots, like along the walls or near the centre. What they do is hold the heat during the day and hand it back at night.
How to Vent a Greenhouse
There are plenty of ways to ventilate your greenhouse. The simplest is to open the doors and any windows that can be opened. Even better is if there are built-in roof vents; you can prop them open to let hot air escape. Though automatic vent openers can help, they’re not essential (they can be costly, too).
Signs your greenhouse needs fresh air:
- The leaves look limp, even though the soil is damp
- Condensation sticks to panels for hours
- A strong, damp, or musty smell develops.
- Mildew or mould appears on plants.
Make it a habit to check the air during the warmest part of the day. After checking a couple of times, you’ll know which areas stay hot and which need venting.
Read our guide to find out more: How to Ventilate a Greenhouse
Greenhouse Pests and Problems
You’re going to run into a few pests or problems; it’s part of greenhouse life. Aphids might munch on your young shoots, mould can pop up if the soil’s too damp, and gnats love hanging around trays. Sometimes a plant just wilts out of nowhere, and you wonder what’s going on.
So, when you’re pottering about, peek at your plants. Check the leaves and the soil, and make sure they have a bit of space between them. If you see aphids, wipe them off. If mould or gnats show up, ease off the watering and scrape away the worst patches.
Might as well get rid of any dead leaves or bits of debris and bin them. Crowded pots are like a playground for pests, so give things room to breathe.
If pests keep coming back, look at sticky traps, biological controls or a suitable organic spray.
FAQ
How often should I clean my greenhouse?
Once a week is enough. Just brush off old leaves and clear out any pots you’re done with. Give the whole place a wash at least once or twice a year to stop pests building up and let in more light.
Do I need shelves or staging?
You don’t need them, but having them gives you more convenience. With shelves, you can keep your trays organised and free up the floor. Even one small rack opens up space in a small and tight greenhouse.
Can I grow straight in the ground inside the greenhouse?
Yes, you can. Dig in some compost, clear out old roots, and you’re good to go. Plants in the ground often grow bigger and need more water, so keep an eye on them.
Do I need a heater in winter?
Only if you’re trying to grow plants that hate the cold. Most hardy crops cope well without one. Good insulation and closing up early in the evening give enough warmth for basic growing.
