Year Round Greenhouse Gardening Reminders

Greenhouse Gardening Reminders for January

January is the month when there is possibly more space in the greenhouse than at any other time of year and the opportunity should be taken to thoroughly wash down the house, both inside and out. This includes cleaning the gravel on the staging, cleaning the heating pipes and treating them with sump oil, and cleaning pots and boxes, in preparation for the busy seed-sowing season which lies ahead.

Cuttings of chrysanthemums should be taken at this time and fuchsias and pelargoniums potted on. Sow seeds of begonias, gloxinias and streptocarpus and germinate in a propagating frame with a temperature of about 18°C. (65°F.).

Towards the end of the month, start to bring pots of narcissi, daffodils and hyacinths into the greenhouse from their plunge beds.

If strawberries are grown in pots then bring these into the greenhouse from the middle of the month onwards, and continue to do so at regular intervals.

Greenhouse Gardening Reminders for February

With the days starting to get longer and the sun having more power, February is the month in which to root your pelargonium cuttings in the greenhouse, at the same time cutting back the old stock plants and repotting them.

Trim back fuchsias, shake the soil from the roots and repot them in fresh soil. Calceolarias should be ready to go into their 6-in. pots, and schizanthuses will be ready for their move into 6, 7 or 8-in. pots. Continue to sow seeds of begonias, gloxinias and streptocarpus as in January. This is also the time to sow freesias, coleus and Primula kewensis. More chrysanthemum cuttings can be inserted, both of indoor and outdoor kinds. Pot bulbs of gloriosas. Take cuttings of Lorraine begonias.

Continue to bring narcissi, daffodils and hyacinths into the house, a few at a time, to provide a continuity of colour. As tulips begin to show their flower buds, they may also be brought into the house.

Start planting up your hanging baskets if fuchsias are being used, putting these in now. Add Ivy-leaved pelargoniums, verbena and trailing lobelia in March and pendulous begonias in April.

Greenhouse Gardening Reminders for March

March brings much longer days and spring begins in the greenhouse long before it does out of doors. Many plants are now making active growth. This is the time to pot Regal pelargoniums, and to stop pelargoniums generally to encourage them to make bushy growth.

Seeds of many summer-flowering plants for the garden should be sown this month. Sow tomato seed about the middle of the month. Start tubers of begonias and gloxinias into growth by putting them into boxes filled with moist peat. Continue to pot the bulbs of gloriosas if this was not completed last month. Also, if freesia seed was not sown last month do this now.

If you have a peach tree on the wall of your greenhouse it will be in flower now and pollination must be attended to.

Perpetual-flowering carnations should be ready for potting on into 5-in. pots, and as poinsettias finish their display they should be cut down to half their present height and kept dry until the end of June when they should be started into growth again to produce material from which cuttings can be made.

As hippeastrums finish flowering the flower stems should be cut down to just above the bulbs. The leaves are now beginning to grow and it is time for regular watering and for feeding once a week with liquid or soluble fertiliser. Cyclamen should be ready for potting into 3 or possibly 4-in. pots.

Sow seeds of Primula obconica, P. sinensis, P. kewensis, impatiens, Solanum capsicastrum, Asparagus sprengeri and A. plumosus. Start watering cacti and succulents again after keeping them dry in the winter. Chrysanthemums raised from cuttings in January will be ready for stopping. Repot cymbidiums when they have finished flowering if they have been in the same pots for a number of years. The same applies to paphiopedilums.

Strawberries in pots will need feeding as they come into flower, and the flowers need thinning to reduce them to not more than 10 on each plant.

Greenhouse Gardening Reminders for April

April is yet another busy month in the greenhouse when the plants are growing rapidly. Many of the bedding plants are ready for moving out into the garden frame. Sow seed of cucumber and melon for greenhouse or frame cultivation.

Cuttings of fuchsias and pelargoniums root and grow on readily at this time of year. Many plants such as chrysanthemums will now be filling their pots with roots and need moving on into larger pots. Over-wintered hydrangeas can be brought into the warmth to start them into growth. Non-flowering shoots from these can be used as cuttings. These will make good plants for twelve months hence.

Cut back all Maidenhair Ferns now and divide and repot them. Pot on other ferns and generally clean them up. Make sowings of Asparagus sprengeri and Asparagus plumosus, if this was not done last month. Plant out your tomato plants in the greenhouse, as soon as the first flower buds appear.

Greenhouse Gardening Reminders for May

Again, May is a very busy month for the greenhouse gardener.

Plant tomatoes in the greenhouse if this was not done in April, and also plant cucumbers and melons in the greenhouse or garden frame.

Many more plants that have been raised for use in the garden will now be ready for gradually hardening off, these being moved first to the garden frame and then to a sheltered place out of doors before planting in garden beds or flower borders.

Seeds to sow during the month of May include those of cinerarias, calceolarias and Primula malacoides, along with Asparagus sprengeri and Asparagus plumosus, if this was not done in the previous month. Thin out the fruits on peaches and tie in the growths. More hydrangea cuttings can be taken and those rooted in April can be potted in 3-½-in. pots.

Spray and fumigate regularly to keep all plants free of pests and diseases.

Greenhouse Gardening Reminders for June

Jobs in the greenhouse, during the month of June, include the final potting of chrysanthemums and cyclamen. Pot on many other plants, before they become starved in their present pots. Begin to feed plants, particularly those growing in hanging baskets, using liquid or soluble fertiliser added to the normal water supply. Many plants will need the support of stakes now, and this should be attended to.

On warm days both the top and side ventilators should be kept open as well as the door, and shading should be provided for such plants as begonias, gloxinias and streptocarpus.

Sow cyclamen seed now. I like to allow at least 15 to 18 months between seed sowing and the production of flowering plants. Calceolaria and cineraria seedlings will need pricking out into boxes.

Plants such as Azalea indica, primulas and camellias should be stood outside. These will need regular watering and feeding to ensure that they develop into good flowering plants for the following season. Arum Lilies should be dried off and rested by laying the pots on their sides in a sheltered spot outside.

Greenhouse Gardening Reminders for July

July is the time when the well stocked greenhouse is filled with many exotic flowers. Chrysanthemums, which are now outside for the summer, need staking and tying and later in the month a programme of feeding should be started.

The later-flowering chrysanthemums are now ready for their final stopping. Pot perpetual-flowering carnations into their final pots. Continue to water and feed hippeastrums to build up strong bulbs for flowering next winter and spring. Prick out cyclamen seedlings as necessary. Some seed may take a long time to germinate, so do not discard the seed pan until enough seedlings for one’s requirements have appeared.

Cucumbers and melons need regular stopping and tying and some of the melons will be ready for pollinating. Tomatoes need feeding and watering, side-shooting and spraying over with water on bright days to assist pollination and the setting of fruit.

Specimens of Solarium capsicastrum should be ready by now for potting into 5- or 6-in. pots. If these plants are then plunged out of doors they will set berries much better than if kept inside. Start cyclamen corms into growth again by watering carefully and spraying lightly overhead to encourage the development of new shoots.

Now is the time to begin taking cuttings of Regal and Zonal pelargoniums, fuchsias, coleus and other plants which are to be kept through the winter.

Greenhouse Gardening Reminders for August and September


August is the time to sow seeds of schizanthus and mignonette in the greenhouse, and there is still time to sow the seeds of cyclamen plants. Make sure that hanging baskets are well supplied with water and that the plants are fed regularly to keep them growing and flowering well on into the autumn.

Climbing plants along the walls and sides of the greenhouse need regular tying in and some cutting back to prevent them keeping the light off other plants.

Cinerarias are ready for potting into 3-½-in. pots, these being placed in the garden frame with shade from the sun. Calceolarias, too, should be ready for potting up in 3-in. pots.


Out of doors we now begin to see signs of autumn and it is time to start planting bulbs of specially prepared hyacinths and Paper White and Grand Soleil d’Or narcissi for flowering in time for Christmas and early in the new year.

More cuttings of pelargoniums can be taken now if they are needed. If it is intended to sow annuals such as clarkia, annual carnations, larkspur, salpiglossis and Sweet Scabious for flowering in the greenhouse in spring this is the time that seeds should go in. Pot schizanthus seedlings into 3-½-in. pots.

As the buds form on chrysanthemums they must be brought inside, and this must be done before the first autumn frosts arrive. These plants will also need disbudding.

Plants such as Azalea indica, Solanum capsicastrum, cyclamen, primulas, cinerarias and freesias which have been stood outside for the summer will also need bringing in. Do not forget to feed these plants at regular intervals. Cyclamen and primulas should have the first flower buds removed to build up the strength of the plants. I like to have my first cyclamen blooms towards the end of October.

Greenhouse Gardening Reminders for October

The greenhouse will probably be packed to capacity with chrysanthemums and other plants which have been brought inside for the cooler month of October. Keep a careful watch on the temperature within the greenhouse and turn some heat on at night if there are forecasts of frost. This will keep the air circulating, which is good for the plants, as well as keep out the frost. Fumigate to keep the plants free from pests and diseases and use the ventilators with care.

During the early part of the month pot the remainder of the pre-cooled daffodils which will be in flower before Christmas. Hydrangeas will need potting into 7-in. pots and calceolarias and cinerarias can be moved to 5-in. pots.

Reduce the supplies of water to hippeastrums, begonias, gloxinias and streptocarpus which will soon be resting for the winter. From now on all watering must be done much more carefully for a dryish atmosphere is necessary if trouble from botrytis is to be avoided.

Greenhouse Gardening Reminders for November and December


Late-flowering chrysanthemums will be at their best during the month of November, which is the time to insert cuttings of perpetual-flowering carnations. Rooted cuttings of fuchsias and pelargoniums need potting into 3- or 3-½-in. pots, and plants at a more advanced stage into 5- or 6-in. pots.

Large fuchsias should have their water supplies reduced because they will be resting during the winter. Reduce, too, the amount of water given to cacti and succulents.

Make a sowing of lettuce seed to provide plants to grow on when the chrysanthemums no longer need greenhouse space, or for planting in the garden frame. Pot on schizanthuses as necessary into their 5-in. pots.


December, the darkest month of the year, and it is necessary to be even more careful with the watering and doubly so with the ventilation in your greenhouse.

The bulbous flowers must be brought into the greenhouse to encourage more rapid growth and get them into flower for Christmas. This applies to pre-cooled daffodils, specially prepared hyacinths, Roman hyacinths and Paper White and Grand Soleil d’Or narcissi. Lorraine begonias will now be needing canes to support their stems and flowers.

As the chrysanthemums finish flowering, cut the stems down to within 9 inches of soil level. It is best to shake the soil from the roots and put them close together in boxes where they take up much less room. These are kept to provide suitable material for cuttings in January and February.

Freesias will be coming into flower and twiggy sticks should be pushed in between the plants to support them.

10. July 2017 by admin
Categories: Featured Articles, Greenhouse Gardening | Tags: , , , , | Comments Off on Year Round Greenhouse Gardening Reminders


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