"I grow dahlias for exhibition.  I grew dahlias in my soil last year but they did not grow well, they appeared to be short of Nitrogen, I struggled to get them to throw side shoots, also they were very tall.  This is only my second year in this garden.  I applied dung in December last year.  Previously the garden was part of a field which was used for grazing sheep".

Lab Ref No. RS114466
Plant type; DAHLIA
Client: John Wallace

Acidity, Alkalinity,Test
pH level of this sample: 6.7 SLIGHTLY ACIDIC

Treatment required to correct pH:  The soil pH falls within the accepted range for dahlia cultivation therefore no adjustment is necessary.

Nitrate Test LOW 10 Milligrams per litre (ppm) [0]

Phosphate Test MODERATE 35 Milligrams per litre (ppm) [2]

Potassium Test HIGH 600 Milligrams per litre (ppm) [5]

Magnesium Test HIGH 290 Milligrams per litre (ppm) [4]

Soil Conductivity: 800 Microseimens/cm.*

* Low salinity, no treatment required.

Figures displayed in brackets thus [ ] refer to A.D.A.S. index numbers.

Remarks; Low nitrate levels are due to the high sand fraction of the sample.  Nitrates are very mobile in light sandy soil, they are easily leached.  This is the possible answer to your problems with small plants.  A slow release fertiliser base dressing, supplemented by a liquid feeding programme to supplement the base dressing is reported to benefit dahlias.  Liquid feed dahlias after four weeks in open ground with a balanced feed (1:1:1) e.g. Chempak No 3.  Change to a higher ratio Potash feed from July e.g. Chempak No 4.  Take care not to overfeed as oversize blooms will result.

Soil composition is only fair, organic matter/humus level seems low although not measured.  Therefore an annual addition of well rotted organic matter (farmyard/cow/stable manure or homemade compost) is recommended to maintain an average level.  Incorporate well into the soil, autumn/winter.  This will stabilise structure, help to maintain humus levels and improve nutrient (especially Nitrates) and water retention which is easily lost due to high sand fraction of the sample.

Drainage; Good
Aeration; Good
Workability: Good
Structure; Fair
Colour; Dark
Water Retention; Poor
Textural Class; Light Soil
Textural Group; Sandy Loam

Deficiences in nutrient levels can be effectively rectified by using either organic or chemical fertilizers. Usually chemical fertilizers are fast acting and almost immediately available to plants, organic fertilizers on the other hand are generally slow to release their nutrients, although there are some exceptions.
Both chemical and organic fertilizer options are detailed below, this allows you to choose the option you wish to follow. Just choose a nitrogen fertilizer, a phosphatic fertilizer and a potassium, and mix in the recommended amounts.
Use this as a BASE DRESSING a few weeks before planting. An alternative approach is to use a ready mixed compound fertilizer, at least two alternatives will be found in the appropriate section below.

Due to the current controversy, and public concern regarding the link between BSE and the human form, CJD. This laboratory is not recommending organic fertilisers based on mammalian sources, e.g. blood, bonemeal and hoof & horn. Although there is no conclusive evidence of a link, this advice has been given as a precaution. However Vitax Q4 is based on organic components and this is a good organic based alternative. Always wear gloves and avoid breathing any dust when handling any fertiisers.

NITROGEN; NITRATE of SODA (16%) 2 ozs. per sq yd. OR NITRATE of AMMONIA (33%) 1 oz. per sq yd.

PHOSPHATE; SUPERPHOSPHATE (17.5%) 1.25 ozs. per sq yd.

POTASSIUM; SULPHATE of POTASH (48%) 0.25 oz. per sq yd.

MAGNESIUM; None required

1. VITAX Q.4 @ The rate of 4 ozs. per sq. yd. (slow release). OR 2. CHEMPAK B.T.D. @ The rate of 4 ozs. per sq. yd.

All figures in brackets refer to the percentage of that nutrient present in the fertiliser.