Cultural Procedures for Chrysanthemums
Where propagation material is being retained, it is important that this be selected carefully. Hot water treatment of the stock may be desirable for eelworm control before the stools are boxed up with good clean compost, when cuttings will freely form with warmth and moisture. It is important not to induce growth too early, particularly in the case of earlies which often produce better from a shorter period of growth. Initial growths from stools are in any case of poor habit and should be removed and discarded.
Rooting and planting of cuttings
Whether cuttings are prepared below a joint or node or merely snapped off is a matter for individual choice, although cuttings below a node are more desirable for amateurs who will often have a lower level of heating with consequent slower rooting.
Cuttings are taken 5-7cm (2 – 2-1/2in) long, trimming off the lower leaves and dipping the base of the cuttings in rooting hormone if this is thought necessary before inserting them 1.25-2cm (½—3/4in) deep and 2.5-4cm (1— 1-1/2in) apart in seed trays or, on a smaller scale, in pots, in a mixture of equal parts peat and sand or for later propagation in John Innes No 1. Jiffy 7s may also be used with success. Cuttings are well watered-in and given bench heat to 12.8-18.3°C (55-65°F) level. Rooting will take place within 7-21 days. Various techniques are practised to induce quicker rooting: mist propagation, polythene bags over pots or boxes, plastic dome covers. Too high humidity can lead toproblems.
When rooted, as confirmed by a freshening of the top growth, or visible evidence of root formation (in Jiffy 7s), cuttings can either be potted into 8cm (3in) clay, plastic or peat pots, using John Innes No 1 or a soilless equivalent or, where applicable, planted out 13 x 13cm (5 x Sin) apart in well-preparedin frames. Plants should be potted or planted firmly. Early flowering varieties which are rooted in mid- to late winter may have to be boxed up in boxes containing compost and kept in the greenhouse until the danger of frost is past and they can be put into frames. Alternatively, frames can be protected from frost by the installation of electrical tubular heaters (preferably controlled by a thermostat) which will maintain the air temperature above freezing point.
Stopping is usually carried out when 15-23cm, (6-9in) growth has been made (up to 38cm/15in with some varieties) and the bottom buds are seen to be breaking naturally (ie anticipating the natural break). It is achieved by the removal of the whole top of the main stem, without removing the first fully developed leaf With programmed crops under glass it is unnecessary to be so exact, the tips of the main shoots being stopped in a routine manner 10-14 days after planting. Stopping should not coincide with planting or potting. After stopping it is usual to thin down the number of remaining shoots (generally 3-5) according to purpose and of course variety, although one or two extra shoots should be allowed to compensate for breakages.
Time of stopping can be critical, especially when showing is involved and it should be noted that varieties which produce the beston second crown buds (having fewer petals or being ball shaped) will require a second stop, which means, in general terms, stopping varieties to be flowered on their first crown buds (and therefore stopped only once) 14-21 days later than those to be flowered on second crown buds, which will be stopped for a second time after an interval of 4-6 weeks, whether in borders or pots. The first stop will, in many cases, be while the plants are in frames or small pots.
Sometimes the break bud develops before the plant has produced sufficient laterals for flowering requirements, and to offset this the top two or three laterals should be stopped by carefully removing their terminal buds before they reach an appreciable size, allowing them to produce second crown flowers which will generally flower about the same time as lower placed laterals or first crown flowers.
Some large exhibition varieties may require stopping 14-20 days earlier than the appearance of the natural break warrants in order to ensure time for the development of a full flower. Conversely, varieties which produce over-full flowers are improved by stopping on the natural break and allowing free development of the upper laterals, removing the lower ones. There can be no general rules, and top exhibitors generally achieve results because they have learned by experience what to do and what not to do.
This will apply to earlies, lifters and tobeing grown under protected cultivation. Ground must be well prepared with a pH of 6.5, phosphate and potash index 4 or slightly higher, magnesium index 2, and salt concentration index 4. A base feed of 136-204g/m2 (4-6oz per sq yd) using one of balanced proportions is usually applied before planting out of doors, but some guidance from analysis is always useful. Planting distances are usually 30 x 30cm (12 x 12in) or 30-36cm (12 x 14in) in beds 1.2m (4ft) wide, although for lifters more space is generally given between the rows to allow easier lifting. Support will be necessary by canes or stout nets, although for lifters nets are obviously not suitable.
Plants in 7.5cm (3in) pots are moved to 13cm (5in) pots once the roots are well through the ball, this being ascertained by holding the pot upside down and allowing the root ball to drop into the hand. John Innes No 2 potting compost is invariably used, with plenty of roughage in the bottom of the pot, the plants being well firmed-up. Final potting into 20 or 23cm (8 or 9in) pots is carried out when once again the roots are well through the 13cm (5in) pots, this time using John Innes No 3 or special compost, roughage and a potting stick to ram the soil in firmly, as uneven potting affects water retention and nutrient release.
One of the main requirements of the growing of chrysanthemums in pots is to have a compost with a high fibrous content which assists the retention of moisture and provides improved feeding for the roots. Most exhibitors try to maintain a stack of loam for this purpose.
After final potting, three strong canes 10-13cm (4-5in) apart are inserted around the edge of the pot and the plants initially supported by strong twine around the canes, later tying the number of shoots left individually to each cane. Pots are placed close-up against each other for a few days to give them some protection, then placed in a line 15cm (6in) apart, usually on gravel or ash paths not recently weedkiller-treated, especially if the usual weedkiller used is with sodium chlorate which can last up to 2 years in the surface of the soil. The paths must be absolutely level, a spirit level being used to check this if necessary. At least one cane per plant must be tied to a strong wire or fence.
Plants must be fed and watered regularly and the pots given an occasional turn to prevent rooting into base, although it has now been established that a considerable amount of moisture is pulled up from the base.
(Chrysanthemums can of course be grown on thesystem in much the same way as .)
Disbudding and lateral removing
Any generalization on disbudding procedure is impossible owing to the differing cultural methods involved. It is usual, however, where single stem or standards are being grown as opposed to sprays (year-round or spot cropping) to reduce to all but the central or terminal bud in the absence of individual preference to the contrary. With spray varieties being grown either direct or semi-direct it is usual to remove the terminal bud to give a better shape of spray, and in addition some stopping of the lower side shoots may be carried out. Lower laterals must also be removed.
Watering and feeding Chrysanthemums
Regular watering and feeding with liquid or solid fertilizer is essential on a regular basis for all chrysanthemums, whether growing out of doors or in pots. Trickle irrigation systems are extremely useful for the watering of large pots. Medium nitrogen liquid feeding should be practised unless growth is too hard, when high nitrogen is necessary, or too soft, when less nitrogen is necessary. The above table is a summary largely for greenhouse grown chrysanthemums, but it is broadly applicable also to conventional pot culture.