Planting Techniques for Chrysanthemums
Direct planting techniques
(for late-struck cuttings, early planting, spot cropping and year-round planting)
Direct planting is often thought to be a very complicated procedure, whereas in fact it can be a lot simpler and less demanding in care and attention than conventional culture. The only difficulty is in obtaining the necessary cuttings in the small quantities desired, as few specialist suppliers are willing to supply less than 50 of each variety.
It is possible to take and root cuttings at the normal period of the year in late winter or early spring and plant them out in greenhouse borders or frames at 23 x 23cm (9 x 9in). These, if stopped once or twice again, will serve as a source of late cuttings which if necessary can be rooted again and the same procedure followed.
This involves planting from early summer until as per the programme already outlined, selecting the single, double or triple stem crops. Beds in the greenhouse approximately 1.2m (4ft) wide must be put in good physical condition by the liberal addition of peat and adjustment of the pH to 6.5, phosphate index 5, potash index 4, and magnesium index 3-4. This can usually be achieved by the application of a standard base dressing at 136g/m2 (4oz per sq yd) or 2 parts hoof and horn, 2 parts superphosphates, and 1 part sulphate of potash and 1 part magnesium sulphate, leaving out the hoof and horn if liquid feeding is to be practised from the outset. Spacings are according to the table previously given. It is important not only to space the plants exactly, but grade out the cuttings so that the smaller ones are placed on the outside of the beds. They are planted firmly and evenly and watered in.
The same procedure is followed for spot or year-round culture.
Seasonal culture for direct planting
It is usual to keep plants more humid for a few days after planting to help them to re-establish themselves. Support by means of stretched 15cm (6in) mesh nylon netting is essential at an early stage of development, raised gradually on posts as the plants grow. Regular, even watering, coupled with temperature control to the level stated in the programme should be the aim, with the object of achieving 12.8-15.6°C (55 — 60°F), especially during early to mid-autumn when buds are being formed.
The flowering period will be as outlined in the programme, either summer for early flowering or mid-autumn to early winter for autumn natural season cropping, with flowering at other times according to the programme followed. It cannot be emphasized too strongly that while the culture of natural season direct planters is relatively straightforward, specialist and year-round cropping requires tremendous precision, particularly where quality is important, and a highly specialized approach to cropping and strict planning is necessary.
The timing for this is stated in chrysanthemum-growing programme 5. Nutrition from an early stage is important to encourage sufficient vegetative growth during the outdoor period, and liquid feeding from the outset may be necessary.
Where plants are put into peat pots, these should be 12-13cm (4-1/2in) and John Innes No 2 or its soilless equivalent used, the plants being placed in rows 15 x 15cm (6 x 6in) apart on a layer of peat and mulched well with peat in order to reduce watering needs. Alternatively the plants can be planted up 15 X 15cm (6 x 6in) apart in goodwith a pH of 6.5 and the standard stated for outdoor planting.
Growth must not be too soft otherwise breakage readily occurs through wind and when planting: wind protection in one form or another must be provided, and considerable care must be exercised when handling the plants. Very careful watering is necessary to avoid checks.
The plants should be lifted into a more comfortable environment before the third week of September at the latest, unless the weather is very mild or temporary cover can be laid on. It is not desirable that budding should coincide with lifting and planting, but when the plants are indoors too soon they tend to make insufficient vegetative growth and to flower on stems that are far too short.
Stopping is carried out as per the respective programmes, unless for single stem or standard crops which are grown on the break bud.
Pest and disease prevention measures and control should be given constant attention.
Plants in pots are better safely housed in early to mid-autumn before any frost occurs, this being particularly important with plants with good bud development. Before housing, the plants and pots should be laid carefully on their sides and given a thorough drenching with a suitable insecticide and aspecific. They should then be allowed to dry off before being taken into the greenhouse pot first to avoid damage to the breaks. Space about 56cm (18in) apart each way.
Keep the greenhouse fully ventilated for a few weeks to let the plants sweat; heat is then given to the 7.2-10°C (45-50°F) level. Watering and feeding must be continued with, it being usual in the latter case to concentrate more on potash to limit growth and encourage better flower colour although there can be no hard and fast rules in this case. Mildew can quickly establish itself under conditions which are too humid, so also can botrytis which causes spotting on the blooms, particularly of white varieties. Pest control should also be given regular consideration.
Before lifting in plants, greenhouse borders which have previously grownare given a good forking and, while fertilizers are usually unnecessary, some ground limestone at 136-204g / m2 (4-6oz per sq yd) is advisable to adjust the pH to the 6.5 level. Plants are lifted with a sharp spade, it frequently being advisable to cut around the root area a week or two beforehand. Whether plants can be lifted with a good root ball depends on soil type, this being difficult with light soils, especially if dry. Growing in plastic or wire baskets is sometimes practised to avoid disintegration of the root ball, while at the same time achieving a measure of root restriction. Plants being lifted must be handled very carefully otherwise side shoots can be broken off, particularly with brittle varieties, eg ‘Loveliness’. Planting in the greenhouse is usually close; 15-23cm (6-9in) apart in rows 30-45cm (12-18in) apart, and thoroughly soaked-in. The greenhouse is kept cool by ventilation and, while some wilting is unavoidable, the plants usually recover fairly quickly and start growing again when heat is given to the 7.2-10°C (45-50°F) level, the same precautions being carried out against and botrytis as described for pot-grown plants. Feeding is stopped when the buds are showing colour.
The canes invariably used as supports for lifters are of course lifted in along with the plants.
Sterilization of borders
Where spot or year-round cropping is practised then soil sterilization, usually by the sheet method, is imperative. For natural season cropping following, experience shows that where the soil is of an acceptable standard nutritionally (generally speaking, if it is acceptable for it will be suitable for ) the soil sterilization carried out for the tomatoes will suffice for the following crop of chrysanthemums in that year. There can, however, be no generalization.
More recentlyor sunken polythene-lined beds filled with soilless media have been used successfully for chrysanthemum culture, also growbags on a limited scale.