Potting Plants Successfully for Greenhouse Growing

Some Popular Pot Plants:


The variegated foliage of this plant makes it an attractive subject for pots, especially in spring and summer. It is, however, a plant which must be kept out of draughts, as the leaves may fall if it is given conditions it does not like in this respect. This is one of the most common troubles. Over-watering will also give rise to leaf drop, and it is best to make sure that the crocking of any pot containing coleus is adequate for best results. Compost must also be well drained to allow free passage of water.

If re-potting is needed, use a rich compost – if possible: 3 parts loam, 2 parts sieved compost and 1 part of coarse grit. When re-potting, do not re-pot too firmly. 

greenhouse Coleus can be raised from seed, but this gives rise to a percentage of green or greenish foliage types, and these should be discarded, keeping only the reddish ones or those which appear promising as far as leaf colour is concerned. 

The usual method of propagation is by cuttings. These are best taken as follows: select a shoot 3 ins. long from the side of the plant, preferably from the lower part, leave the tip intact and neatly remove the lowest pair of leaves. Cut through the leaf joint and insert firmly in sand, or half sand and half compost in a 3 in. pot. Water carefully as required. 

If long shoots at the top of a plant are trimmed back to keep the shape neat and well balanced, the tips of such shoots can also be used for cuttings.


Chrysanthemum Plants

 Some of the dwarf varieties are very suitable as potting plants and the yellow, Jante Wells, is probably the best known. It is best to grow these in 5in. pots, and to plan for a September and October display. Cuttings are taken in April, rooted in the same way as described in “Growing Early Flowering Chrysanthemums”, and, when ready, moved into 3 in. pots.

When the plants are well rooted in these, pot them on to the 5 in. size. A good potting mixture for this purpose is 2 parts loam, 1 part compost, 1 part peat and 1 part coarse sand. To each bucketful of the mixture add a handful each of bone meal, hoof and horn and wood ash.

If Jante Wells is being grown, when the plants are about 5 ins. high the tops should be taken out, to encourage side shoots and give bushy compact growth. The plants should be hardened off and then stood out on a hard base for the summer months. They need to be spaced out, as growth develops. Pay careful attention to watering throughout, and feed with liquid manure every 10 to 14 days. These subjects should be taken indoors in September, as the buds show colour, and grown under cool, well ventilated conditions. 

There is a group of varieties called the Dwarf Lilliputs that are very suitable for this type of cultivation, all being 8 to 12 ins. high and of compact, neat habit. None of these need stopping or staking. These varieties are very free flowering; some that can be recommended are: Cadet, red; Doris, lilac; Isis, rose pink; Osiris, rosy-mauve, and Pimpernel, chestnut red. They make a valuable contribution to an autumn display.



These potting plants need heat through the winter months and are grown chiefly for spring display. The dwarf multiflora varieties are easiest for small batches. Seed is sown in June, and the seedlings can be pricked out into 3 in. pots. These plants must have good drainage and, when potting finally into 5 in. pots, make sure that enough crocks are laid in position. For the autumn and winter, cool but frost free conditions are necessary.

These bold and colourful potting plants make an attractive display but demand rather more than usual care and attention in their management. They call for extra care with watering, in that too much causes damage to the roots. Often when the leaves are seen to be flagging, it is assumed that the compost is dry and more water is given. As a result, the plant can be killed very quickly.

Before watering is done it is essential to tap the pots sharply to ascertain moisture requirements. Only give water when the compost is dry, i.e. when the pot ‘rings’ on being tapped. If in doubt delay watering for the time being. 

Apart from the root troubles mentioned earlier one of the chief problems can be aphids, and these pests are quickly attracted to the soft tips of the plants. Regular spraying with derris preparations may be essential to keep these plants clean of such pests. 

I find that I can do best with these plants by growing them in a very sharply-drained compost and I like the following mixture best of all: 3 parts loam, 1 part coarse grit, and 2 parts compost. 

Do not start feeding pot plants until the buds are well developed as too much, too soon, can cause an excessive amount of foliage to be produced at the expense of the flower.



This is one of the most popular potting plants for September to Christmas flowering. Many colours are available, but pink and red varieties are the most popular. The plants need a long growing season, seed is sown in August of one year, for flowering during September to December the next year. Sow the seeds in 5 in. pots under glass. When the young plants are 3 ins. high, which will be in early autumn, transfer them to 3in. pots, in a mixture of 2 parts loam, 2 parts compost and 1 part sand. 

In spring move the plants into 5 in. pots, in which they will flower. Use the same mixture for this potting, but place a lin. layer of rotted compost in the bottom, over the crocks. Good drainage is essential for cyclamen. For the summer months stand the pots out in cold frames, paying careful attention to watering. 

Cyclamen will respond to liquid manure feeds throughout this period, and until the buds show colour. 

Bring the plants into the greenhouse in September, before the first frosts threaten. Grow under cool conditions, space out the pots so that they are not crowded and avoid over-watering.



These colourful plants flower through the summer months, and there is a wealth of varieties, of which the double white and pink Ballet Girl is popular, also the double pink Fascination. 

Propagation is by cuttings which can be taken in early spring, using new side shoots 3 ins. long, removing the lower leaves, and inserting firmly in a sand and 1/2 peat compost. Pot up into 3 in. pots when rooted, and later into 5 in. pots for flowering. Staking is needed for most varieties. Liquid manure feeds are of especial benefit and should be given every 10 to 14 days in summer. 

Make certain that this subject is kept out of draughts, which can cause the flowers to drop. Another reason for this same trouble is uneven temperature conditions, i.e. extreme variations, and careful attention to this point can prevent disappointment. 

When the flush of flowers is over, the main branches (shoots) can be pinched back to encourage new growth, and to keep the general habit of the plant neat and well furnished. Remove about a third of the shoots in each case. 

Watering should be attended to regularly; never allow plants to flag, as this, too, can cause flowers to drop. When water is required, fill up the space available, more than once if necessary, and then leave, until the compost dries to the stage when the pot “rings” if rapped with the knuckles.



For an easy to grow pot plant, polyanthus should be tried. If a few plants are lifted during mild weather, and potted into a pot size just larger than the width of the ball of roots, they can be relied upon to give some flowers indoors, so long as they are given cool conditions, not over-watered, or kept in too damp an atmosphere. 

When lifting a few potting plants in autumn select those with ample crowns, that is the central fleshy portion, and not over much leaf. Remove any brown outer leaves cleanly. When potting, use a light well-drained compost, of 3 parts loam, 1 part sand and 1 part of leaf mould. Pot fairly firmly, making sure that the pots are well crocked, as free drainage is important with these plants. 

Such potting plants will make a useful Mothering Sunday gift. If three or four pots are grown, if possible of different colours, an appropriate choice can be made to suit individual preference. Do not try to hurry the plants when they approach the flowering stage, as they do not respond to over-warm conditions.



These are valuable plants for summer flowering and cuttings can be taken from mature plants in September, or spring. Insert these around the edge of a 5 in. pot in a sandy compost. Pot up when rooted, singly, into 3 in. pots, in J.Innes Potting compost no.1 and later when the pots are filled with roots into 5 in. pots, using J.I.P.2 or 3 parts loam, 1 part compost and 1 part of sand. Feed with liquid manure until the flowers open. A popular pink variety is Carisbrook, and, if only one variety is grown, this can be the choice. 

It is essential that these plants be given frost-proof conditions in winter. They need very little watering during these months, and the shoots can be cut back in autumn, or early spring, to encourage bushy, well-shaped pot plants.


Tuberous Begonias

These colourful subjects are grown from corms, which are started into growth in a tray of peat, in the greenhouse in March (or earlier if desired). When they have made roots about 2 ins. long, move each plant into a 3 1/2in.pot, and use 2 parts compost, 1 part loam and 1 part sand for the potting mixture. Later, move on to 5 in. pots containing the same mixture, but place a 1 in. layer of compost or rotted manure over the crocks first. 

A small stake is needed, and early flowers should be pinched off, to improve the size in those which follow. Feed weekly with liquid manure when flowers show colour or use soot water one week and liquid manure the next. Begonias are excellent potting plants and show good response to this type of feeding.


19. September 2010 by admin
Categories: Greenhouse Gardening | Tags: | Comments Off on Potting Plants Successfully for Greenhouse Growing


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