Bulbs in the Greenhouse

These are planted in pots of one of the JIP composts, often with sharp drainage below. Small bulbs should be covered with their own depth of soil and large ones may be only half submerged. Bulbs near the surface are more likely to need careful staking.

Bulbs being forced for cutting are often planted in deep boxes as appearance is not usually so important. Otherwise they are treated as bulbs in pots.

Bulbs for the alpine house or cold frame are usually small; they are often planted in pans but if a plant needs a deep root run a pot should be used. Very good drainage is necessary.Bulbs in the Greenhouse

Feeding Throughout the time that the plant is growing actively it should be fed. In pots there may be enough fertilizer in the compost to feed the plant for six weeks, but after that liquid feeds should be given once a fortnight. If a plant makes most of its growth during the winter it will need feeding during this season, even if you normally stop feeding in autumn and do not begin again until spring. Generally speaking the fertilizer used should be one with a rather high potash content to assist ripening which is very important in many bulbs from warm parts of the world. Never feed a plant in dry soil, always water it first.

Watering Many bulbs fail completely if they become dry at any time when they are growing, but only plants which are growing strongly need much water in winter as less is lost by evaporation than in summer, and such plants should be watered on the soil only as water on the leaves causes too sharp a drop in temperature and can lead to fungal infection becoming serious.

Ripening This is the name given to the complex chemical processes which occur inside the plants both before and after the leaves die down. Potash appears to be essential for these changes, as are the gradual withdrawal of water and, in many but not all, baking by sun heat. The plants most in need of this are those which experience drought during their resting period, e.g. nerines.

It is important with plants needing sun ripening to ensure that they do not get smothered with other plants, including weeds. Internal changes continue during the resting period and can be adversely affected by incorrect storage temperature.

Resting When the leaves of a bulb start to turn yellow watering must stop and the bulb be rested, unless experience shows otherwise. All the bulbs corms and tubers listed here have a definite resting period. Many can stand being dried right out; tulips like a thorough baking.

As far as many greenhouse pot plants are concerned the bulbs or corms are best left in the soil in the pot until it is time to start them into growth again. This prevents them withering as much as they would do in the open air and keeps them relatively safe.

Plants in the garden should be left to finish their growth before lifting, cleaning and sorting. If they are not to be lifted it may be wise to mark the site.

Grass with bulbs in it must not be mown until the foliage turns yellow, nor should the foliage be picked with the flowers. The leaves make the stored food.

Bulbs in bedding schemes may need to be moved before it is time to rest them. They can be lined up in trenches to finish their growth. Bulbs which were started in pots and plunged up to their rims in the formal beds are easier to cope with.

Bulbs which have been forced for use in the house or for cutting should not be used again for this purpose the following year. Starting into Growth Bulbs still in pots can be put into fresh compost like new bulbs, or some of the old compost can be removed and replaced by fresh, or the whole pot ball can be transferred to a larger pot and top dressed. It is usually, but not always, necessary to water the soil to start growth. If a pot shows signs of growth it must be watered, but the amount given at first is usually modest.

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