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Greenhouse Growing Guide

by Matt W (Greenhousestores) Greenhouse Fruit and Veg

What can I do in my greenhouse all year?

Our Greenhouse Growing Guide gives a month by month guide on what to grow and when. A greenhouse allows you to grow vegetables all year round. It's a great place to start for Greenhouse Beginners.

  Tasks Plant
November/December
  • Remove shading and clean glass, framework and staging with garden disinfectant
  • Repair any cracks or holes which could cause heat loss
  • Insulate greenhouse
  • Ensure gutters and downpipes are not blocked with leaves
  • Keep greenhouse dry and cool, and ventilate on sunny days
  • Ensure that heaters are working properly
  • Clean and tidy flower pots, trays etc and store neatly, ready for spring
  • Store Fuschia and Hydrangea plants under staging for winter
  • Store Chrysanthemum and Dahlia tubers
  • Plant Iris bulbs ready for spring
  • Pot on hardy annuals such as Pansies and Sweet Peas ready for bedding in the spring
  • Pot up perennials such as Lupins and Delphinium
  • Sow types of Lettuce, Carrots, and French Beans
  • Pot up Chives, Parsley and Mint for winter supply
January
  • Maintain temperature above 45ºF
  • Keep plants well lit but cover if possibility of frost
  • Water plants according to their individual needs
  • Don’t wet plants or staging to avoid diseases
  • Check for slugs and pests
  • Order seeds and compost ready for spring
  • Feed spring flowering bulbs ie. Hyacinth, Crocus and Narcissus
  • Store Polyanthus and container-grown Roses inside
  • Take Chrysanthemumcuttings
  • Pot up rooted seedlings, such as Pelargonium
  • Sow some bedding plants in heated propagator, ie Lobelia, Verbena and Carnations
  • Plant Early Potatoes for cropping in May
February
  • Water more often, but make sure soil not overwatered
  • Check for frosty weather and keep temperature constant
  • Cover tender plants if necessary
  • Spray pests if necessary
  • Prepare seed trays
  • Sow Bedding Plant seeds
  • Bring stored Fuchsia Hydrangea and Dahlia into sunlight
  • Sow Tomato seeds
  • Sow Onions, Parsnips, Sprouts, Cabbage, Broad Beans, Peas and Aubergines
  • Pot up Strawberry runners
March
  • Keep temperature between 45ºF and 65ºF
  • Heat greenhouse at night and ventilate during day
  • Use liquid fertiliser for young plants
  • Watch for greenfly, whitefly and red spider mite and spray if necessary
  • Use capillary matting if beneficial for watering
  • Prepare hanging baskets
  • Prick out Bedding Plant seedlings from last month and sow later seeds
  • Take Chrysanthemum and Fuchsia cuttings
  • Prick out Tomato seedlings
  • Sow Cucumber seeds
  • Sow Courgette, Celery, Sweet Corn, Runner Beans, Leeks and Peppers
April
  • Keep temperature between 45ºF and 70ºF
  • Open roof vents
  • Use shading on sunny days, or cover seedlings with newspaper
  • Keep watching for pests Feed growing plants regularly
  • Use less heating and remove insulation
  • Sow Marigold seeds
  • Prick out last month’s Bedding Plant seedlings and harden off
  • Plant out Dahlia cuttings, Pansies and Sweet Peas
  • Feed Tomatos, pick out side shoots
  • Plant Cucumber plants into grow bags
  • Sow Marrow and Courgettes to plant out in May/June
  • Begin to harvest Strawberries
  • Re-pot and split some Houseplants
May
  • Keep temperature below 80°F when sunny
  • Use shading, especially on south facing glass
  • Heating may still be required at night
  • Open all ventilators if necessary and open door
  • Damp down floors if weather sunny to cool and humidify greenhouse
  • Feed and water plants regularly
  • Pot up any cuttings which have rooted, ie. Fuschia
  • Take cuttings from Houseplants
  • Harden off Bedding Plants
  • Make up Hanging Baskets and Tubs to put out in June
  • Harden off Dahlia plants
  • Train up Tomato and Cucumber plants, feed and water
  • Harvest Lettuce, French Beans, Potatoes and Strawberries
June
  • Stop using greenhouse heating - service and store heaters until winter
  • Keep using shading as plants prone to scorching
  • Keep temperature down by continued ventilation
  • Feed and water plants regularly
  • Damp down floors if weather sunny to cool and humidify greenhouse
  • Move plants for garden out of greenhouse (harden off first)
  • Clean and tidy up plant pots and trays
  • Move Carnations and Chrysanthemum outside
  • Move Hanging Baskets and Tubs outside
  • Plant summer flowering Bedding Plants in garden
  • Harvest early Tomatoes and Cucumbers
  • Harvest Lettuce, Carrots, French Beans, Beetroot, and Radishes
July
  • Keep using shading as plants prone to scorching
  • Keep temperature down by continued ventilation
  • Feed and water plants regularly
  • Damp down floors if weather sunny to cool and humidify greenhouse
  • Take cuttings
  • Move Fuchsias and Pelargoniums outside
  • Move container grown Roses outside
  • Take cuttings of shrubs such as Forsythia and Weigela
  • Harvest Tomatoes and >Cucumbers
  • Sow Parsley
  • Harvest Lettuces, Radishes and Peppers
  • Peg down Strawberry runners
August
  • Watch out for mould and use fungicide if necessary
  • Regulate heat using ventilators
  • Feed and water plants regularly
  • Take cuttings
  • Plant bulbs
  • Plant Hyacinth, Narcissus and Cyclamen for Xmas and Primula
  • Take Fuchsia and Pelargonium cuttings
  • Take Hebe and Lavender cuttings
  • Harvest Tomatoes and Cucumbers, Lettuce, Radishes and Peppers
  • Plant Potatoes in pots for Xmas
September
  • Temperature can fluctuate and heaters may be required
  • Remove shading so maximum light in greenhouse
  • Bring in frost sensitive plants from outside
  • Check plants for pests before bringing in
  • Bring in pot plants before frosts arrive
  • Sow Pansies and Sweet Peas for spring
  • Store Pelargonium and Fuchsia plants
  • Harvest Tomatoes, Peppers and Aubergines
  • Clear up Cucumbers
October
  • Maintain temperature above 45°F
  • Ventilate only on a warm day
  • Water plants sparingly and carefully
  • Remove dead heads, fallen leaves etc to prevent mould
  • Bring all half hardy plants inside
  • Insulate greenhouse again if necessary
  • Plant Tulip, Hyacinth, Crocus and Snowdrop bulbs ready for spring
  • Bring Crysanthemums indoors and cut flowers
  • Lift Tomato plants when crop finished
  • Harvest Tomatoes, Peppers and Aubergines
  • Sow spring cropping Lettuces

Plant Selections for a New Greenhouse

A greenhouse is a piece of garden infrastructure that serves many horticultural functions: it can be an "orangery" for potted plants that aren’t quite winter hardy, a summer home for crops that need a bit of extra heat, and a sheltered space to start all kinds of new seedlings for the season.

For the gardener looking to get a head start on cultivation during the cooler months of spring, there are a variety of plants that can be easily germinated and cared for through the seedling stage in a greenhouse.

Below is a list of some of the more easy­to­grow selections for spring germination in a greenhouse.

Brassicas & Other Leafy Greens

Brassicas are plants in the cabbage family. Generally, they are cool­weather crops, and will germinate even when soil temperatures as low as 10C. Therefore, they are some of the first plants that can be started in a greenhouse, in late winter or early spring (depending on the current and expected temperatures of the year).

"Leaf vegetable" ­­on the other hand­­ is kind of catch­all term for plants that are grown for their leaves, belonging to a wide variety of botanical families: not just brassicas. Lettuces, for example, are in the A steraceae (daisy or aster) family.

After being planted in seedling flats and growing their first set of "true leaves", most brassicas and leafy greens can be moved out to a cool or covered section of the garden.

Brassicas to grow:

  • Asian Greens

    Asian Greens

    Asian vegetables like pak choi (also known as bok choy), chinese or nappa cabbage make a tasty addition to a stir fry.

  • Broccoli

    Broccoli

    Most broccoli purchased in stores is a single cultivar: calabrese broccoli. From seed, however, gardeners have an array of options: purple sprouting broccoli, for example, gives a flower head full of dark and antioxidant anthocyanin pigments.

  • Brussels Sprouts

    Brussels Sprouts

    Growing up the stalk of the plant, these "mini-cabbages" are an attractive and healthy addition to the garden.

  • Cabbage

    Cabbage

    A classic of European cuisine and gardens, both red and green cabbages are experiencing something of a culinary renaissance, owing to their extremely rich profile of vitamins, minerals, and antioxidants, and long shelf life.

  • Kales

    Kales

    Classed as a superfood, kales are also extremely ornamental: cultivars like "Red Russian" and "Dinosaur" like grow into attractive palm-shaped plants that can be harvested all summer long.

Leafy greens to grow:

  • Chard

    Chard

    Closely related to beets, chard is a pleasantly earthy-tasting leaf vegetable. Cultivars like “Rainbow” boast brightly-coloured stalks, coming in shades like pink, red, orange, yellow, and white.

  • Endive

    Endive

    A bitter favourite of Italian cuisine, endive or chicory can be sown in a greenhouse in spring, but perpetually cultivated as a perennial thereafter, as it re-grows from a thick taproot. Come harvest time, it is best served sautéed.

  • Lettuce

    Lettuce

    Lettuce is a crop that goes so far beyond what is seen in supermarket shelves: fresh-plucked greens don’t need to be selected to shelf life, so heirloom or exotic cultivars like the bright red and curly-leafed "Galactic Lettuce" are perfect for the home gardener.

  • Spinach

    Spinach

    Originating in Asia, this classic Amaranth-family green is loaded with nutrients and can be plucked from all summer long.

Cucurbits

Belonging to the botanical family Cucurbitaceae, these vining plants are often sown indoors, and transplanted out (or to a permanent, larger pot) once they have their first set of true leaves.

Care should be taken not to sow them too early in a greenhouse, because after they grow to a certain size, they don’t like being transplanted. They are best sown in late spring, after the risk of frost is passed and things start heating up.

Additionally, for the cucurbits that need to spend the entire summer in a greenhouse, care should be taken to open the vents every day during blooming time, in order to let pollinators in: otherwise, they need to be pollinated by hand.

Cucurbits to grow:

  • Cucumbers

    Cucumbers

    Cucumbers come in cultivars that are suited to both indoor and outdoor cultivation, as well as both mounding and vining forms: take care to read the seed package to see exactly how to cultivate the variety in hand. Exotic relatives of the cucumber, like the Kiwano -also known as the African horned cucumber - can be grown in a greenhouse all summer.

  • Gourds & Pumpkins

    Gourds & Pumpkins

    A favourite come autumn, gourds both decorative and edible come in an amazing array of forms and colours: warted, smooth, elongated, bottle-shaped, round, striped, tiny, enormous are just a few descriptors. For a useful addition to a garden of gourds, the “Luffa” or loofah gourd can be grown in a greenhouse, and the fruit dries to produce a natural abrasive sponge-like tool for the shower!

  • Melons

    Melons

    Muskmelons like the French heirloom "Charentais", or super-sweet watermelons like the "Sugar Baby" are easily cultivated from seedling stage to harvest in the warmth of a greenhouse.

  • Squash

    Squash

    Coming in green, gold, and orange colours; oblong, bottle, and "pattypan" shapes; and winter and summer harvest times, squashes are a multi-purpose crop.

Nightshades

These plants, belonging to the botanical family Solanaceae, are unexpected relatives: most gardeners don’t know that their tomatoes are related to both tobacco and petunias. They are generally heat-loving tropicals, most originating from South America.

Most of these plants benefit from "buzz pollination", which is something bumblebees provide. For those grown all summer in a greenhouse - barring the presence of bumblebees - they can be hand-pollinated with an electric toothbrush.

Nightshades to grow:

  • Aubergine

    Aubergine

    The large purple aubergines - or eggplants - seen in the supermarket aren’t the only option: this fruit also comes in white ("White Casper") and purple striped ("Antigua") colours, as well as round ("Aswad") and elongated ("Fond May") forms.

  • Physalis

    Physalis

    Also called "ground cherries", these sweet little fruits grow packaged in their own little lantern-like casing, and are a decorative addition to summer salads. Started in a greenhouse in spring, most cultivars can happily be transplanted outdoors.

  • Pepino

    Pepino

    Perhaps a little exotic, this nightshade tastes like a honeydew and a cucumber: the name means "sweet cucumber" in Spanish. This fruiting tropical will give the best results cultivated in a greenhouse all summer long.

  • Pepper

    Pepper

    With sweet, mild, and super-hot options available, peppers can be cultivated all across the Scoville scale. Most are more productive spending the growing season in a greenhouse.

  • Potato

    Potato

    Though potatoes are an impractical crop to grow in a greenhouse, they can be "chitted" or sprouted there in late winter or early spring.

  • Tomato & Tomatillo

    Tomato & Tomatillo

    Both tomatoes and the smaller tomatillos vary between cultivars as to their cold-hardiness over summer. Some can be germinated in a greenhouse and then transplanted-out, whereas others should be cultivated inside a greenhouse all summer. Heirloom cultivars can give a huge range of colours, sizes, and patterns that are not typically available in a grocery store.

Tropical Annual Flowers

All the delightful annuals that can be found in flats in a garden centre can instead be started at home from seed, in a greenhouse. The options are too numerous to list, but browsing the seed selections for flowers at a local store is a good place to get started.