Crop Production Info
Dahlias as Pot and Container Plants
Crop Production (Page 3)
Plant Height and Growth Regulator (PGR):
Ancymidol (A-rest) is an approved plant growth regulator (PGR) to control the height of pot dahlias. At an early growth stage it is most effectively used as a soil drench, applied on a uniformly moist, bark free soil medium. It should be applied when shoots are approximately 0.25 inch long. No later than 2 weeks after planting for a greenhouse grown crop. For outdoor culture this stage will be reached a little later, while overall PGR requirements tend to be lower.
Ancymidol also can be used as a foliar spray (50-100 ppm) applied when flowerbuds become visible to limit the flowerstems to elongated above the foliage. Sumagic is also effective for this purpose; at 10-20 ppm.
Index on A-Rest requirements and starting rates for soil drench for different Cultivar Groups:
| A-Rest Requirement | Rate mg/pot | Cultivar Group |
| Low | 0.5 | Short Compacts |
| Medium | 0.5-1.0 | Strong Intermediates |
| High | 1.5-2.0 | Tall Strong Stemmed |
* One liquid ounce of ancymidol contains 7.8 mg of active ingredient
A-Rest starting rates and the number of pots which can be treated from standard Soil Drench dilutions:
| Required Rate | Standard Soil Drench Dilutions | Number of different sized pots which can be treated with standard solution | ||
| Rate mg/pot | Ancymidol/Gallons water | 6" pots drench with 4 liquid ounce/pot | 8" pots drench with 6 liquid ounce/pot | 10" pots drench with 8 liquid ounce/pot |
| 0.5 | 1 quart/15.6 | 500 | 335 | 250 |
| 1.0 | 1 quart/7.8 | 250 | 167 | 125 |
| 1.5 | 1 quart/5.2 | 167 | 111 | 84 |
| 2.0 | 1 quart/3.9 | 125 | 83 | 63 |
* ancymidol is marketed in quarts with 250 mg/quart of active ingredient
Most Common Problems:
Snails and slugs eat the tender shoots, right after they break. Check stacked and outdoor grown containers and use a slug bait, Adress T/O (acephate 75%) or Durham Metaldehyde granulates 3.5 (metaldehyde 3.5%).
Aphids, beet army worms, red spider, white fly and thrips are most common insects encountered in dahlias.
To control these pests a good spraying program, started when first bud become visible between foliage, is recommended. Orthene (acephate 75%) works well to control most insects. Duraguard ME (chlorpyrifos 20%) is best to control beet army worms, cucumber beetle and spider mites which start to build up in warmer weather. Be sure to spray top and undersides of dahlia leaves. Thrips do hide in young flowerbuds, check crop when first buds appear. Disbud heavily infected crop to increase effect of pesticide.
Root rot is prevented through the use of a sterilized soil mix and a regular fungicide program alternating materials effective against Pythium, Rhizoctonia.
