The Gardeners Almanac

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My Back Garden

Growing 'Indoors' or 'Under glass' in May


This is the time for getting lots of stuff out of the greenhouse to harden off for planting outdoors.

Idealy place these plants in a well ventilated coldframe.

If a Coldframe is unavailable move plants outdoors during the day and return them into the greenhouse each evening.

Note: As with most advice on gardening the advisors location will often influence the content of the advice.

To alleviate this problem I have produced this chart indicating how you can make adjustments to the timing of events as seen in this website.

I hope you find this useful! .......Tg

Week 18 - 30th Apr. to 5th May.

Wash dust off indoor foliage plants in the shower or with a pump spray.

If not already done, prepare greenhouse beds for future plantings.

Similarly,remove winter insulation and possibly consider fitting some shading.

Ensure seedlings are out of direct sunlight, and regulary inspect them for pest / disease damage.

Feed Aeonium, Ficus, Strelitzia with a balanced Water-Soluble fertiliser.

Place Berberis seedlings in coldframe to grow on.

Re-pot Freesia, and divide if necessary.

Pinch out fruiting laterals on Grape vines.

Pot up Melons, and Sweet Peppers if necessary.

Pot up new Pleione bulbs, or re-pot established plants.

Week 19 - 6th May. to 12th May.

Plant out Tomatoes.

Alternatively, plant Tomatoes out into large containers or Growbags ready for placing outdoors when all fear of frost has passed.

Increase watering of Draceana.

Week 20 - 13th May. to 19th May.

Plant out Aubergines and Sweet Potatoes.

Deadhead Auricula and collect seeds if required.

Check Auricula root system for root pests.

Pot up previous seasons Calceolaria and Mimosa seedlings.

Prepare bed / pots for Cucumber and Watermelon.

Commence feeding Peach / Nectarine trees.

Week 21 - 20th May. to 26th May.

Plant out year old Azaleas into coldframe, or nursery bed.

Plant out Chilli, Cucumber, Melon, Sweet Peppers, and Watermelon seedlings.

Commence feeding Streptocarpus.

Pot up Calceolaria.

Place potted Camellia outdoors for the summer.

Week 22 - 27th May to 2nd June

Commence feeding Aucuba, Bougainvillea, and Zantedeschia plants.

Re-pot Calathea if required.

Manually pollinate Peach / Nectarine trees.

Place Cymbidium / Orchids in sunny position.

Move potted Figs outdoors for the summer.