Ickenham and Swakeleys Horticultural Society

Growing advice
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Onion pest is likely to spread.

Allium Leaf miner is spreading in Britain, attacking onions, leeks, chives, garlic and shallots and may also affect ornamental species and cultivars of Allium. Signs include characteristic white lines of puncture marks in the leaves from feeding adult males and stem and damage caused by burrowing larvae.  Ultimately, plants rot from secondary infections of bacteria and fungi. No effective insecticides are available to home gardeners. For further information visit www.rhs.org.uk/advicesearch and enter ‘alliumleaf miner’.

The spring season is when we should be preparing the ground for the bounty to come, hence the second edition of an article first published in February 2003.

In short, Nitrogen has a marked effect upon the rate & vigour of growth & the colour of foliage. Phosphorous also enhances growth but is most beneficial on roots which grow freely when it is abundant. Potassium/potash is the principal fruit forming fertiliser.

If you want to know more about what type of soil you have, (ie acid, alkaline, or neutral) why not buy a soil testing kit at the Hut. The cost is only 70p (RRP 2.10) and could save you a lot of money, both in applying the right fertiliser but also to ensure that you won’t lose expensive plants by planting them in unsuitable soil.

Acid soil = below 7pH. Ideal fertile soil = 6.5pH to 7pH. Above 7pH = alkaline soil. Below 5.5pH or above 8pH = real problem soil so seek advice from the Hut.

As dosage is all important we have prepared a free leaflet quantifying the application rates per square yard. Please pick one up from the concrete hut.

Product and typical N:P:K ratios.

When to use and notes.

(N = nitrogen, P = phosphorous, K = potassium/potash).

Bone meal (phosphate).

Spring. Summer. Autumn. Winter. Do not apply around lime hating plants as bone meal brings about an alkaline reaction in the soil.

Epsom salts

Spring. Summer. Autumn. Year round for pot plants.

Fish, Blood, Bone 6N:7P:6K

Spring. Summer. Autumn. Base & top dressing.

Garden lime 

Spring. Autumn. Winter.  Do not mix with or apply within 2 weeks of using other fertilisers.

Growmore 7N:7P:7K

Spring. Summer. Autumn. Base & top dressing.

John Innes base 5N:3P:10K

Spring. Autumn. Base dressing & for making up John Innes composts.

Lawn sand

Spring. Summer.  Different brands may vary the ratios.

Lawn Weed & Feed 6N:4P:2K

Spring. Summer.  Different brands may vary the ratios.

Rose fertiliser 5N:6P:10K

Spring. Summer. Autumn. Different brands may vary the ratios. Use as base & top dressing.

Sulphate of ammonia (nitrogen)

Spring. Summer.  Uses up lime in the soil and should only be applied to adequately lime ground; but see Garden Lime above. Use as base and lawn dressing.

Sulphate of iron

Autumn. Discourages diseases, fungi, moss, weeds and worms in lawns.

Sulphate of potash (potassium)

Spring. Summer. Autumn. Base & top dressing.

Superphosphate of lime (phosphate).

Spring. Autumn. Base dressing.