Blue Mould on Bulbs

This daffodil bulb is infected with Blue Mould, caused by a penicillin mould (fungus). A dark rot, usually at the base of the bulb (it can also be on the side), causes softening of the tissue.

The mould usually enters the bulb from the soil (often from a wound), but symptoms only develop during storage at too high a temperature in damp conditions. Infected bulbs rot in the soil after planting, and infect the surrounding soil with the disease.

So always plant only firm healthy bulbs and discard any which are suspect. If you damage any bulbs, dust each wound with sulphur powder.

Begonia Flower Size

This is the begonia which was placed in the propagator in early spring to bring it on. The flowers are smaller and the stems are longer than the other plant which was allowed to grow naturally. Both plants are in 38 cm (15 inch) pots.


Of course, this could be because there are more flowers on one plant. But it usually happens that cool-grown plants turn out best (are stronger and have larger flowers).

Die-Back on Conifer Hedge

After a recent cutting, this Leyland Cyprus (Cupressocyparis leylandii) hedge is showing signs of die-back (the brown bits), a problem for a few years now. It hasn't grown much this year; this is the first cut.

However, the other half (about 2/3 actually), which was cut just before the end of the hot dry spell, is clear of die-back.

I gave the complete hedge a couple of foliar feeds of 'Phostrogen Plant Food (14-10-27)' - one in March, then another in April. I think this has hardened the foliage enough (because of the high potassium (K) to nitrogen (N) ratio) to make it less attractive to aphids (which I am told cause the die-back problem, though I have never actually seen any - they seem to have disappeared by the time the damage is noticeable).

To some extent, the treatment has worked. But why on one part but not another is a mystery. There seem to be lots of these, this year.

I have found that if I cut out the dead back to the wood (but careful not to go too far), the hedge grows back into the hole within about 18 months. It would be really good to have a full cure.

Hollow-Tined Lawn

Before top-dressing the complete lawn, I hollow-tined a small part comprised of wet heavy soil.

My lawn is a problem because the soil varies in texture from almost clay at one end, to almost sand at the other (yes, I know it's just right in the middle, and I can't have everything; but it's still difficult to manage).

I don't know if you can see (probably not) that the spacing between rows varies from about 10 cm (4 inches) to about 12.5 cm (5 inches). I only tined a few yards. I would have done more, but the tiner kept clogging up.

However, I feel that, provided water can get into the turf, the best time to aerate the lawn is after the end of cutting: and there's still over a month of this left, yet.

Nevertheless, I have found that deliberate aeration greatly enhances root growth. This is important, because I believe that the grasses grow a new root system each season. We are always starting each year afresh, so to speak.

Re-seeding
I added about 17.5 grams per sq metre (1/2 oz per sq yd) of grass seed before I applied the top dressing.

Geranium Cutting Update

This geranium cutting has done really well since it was taken about a month ago - much better than if it were shorter, I am sure. This definitely seems like the way to go.

Testing the Soil Acidity

Before applying the top-dressing, I added some limestone to remove the soil acidity after testing the pH (acidity level) with an electronic meter. This is not an exact science. But it does give some indication, especially when the average of a few samples is used.



A ph of 7 indicates neutral. As the pH goes lower, soil becomes more acid; and vice versa.

About pH 6.5 suits most (but not all) plants. Calcifuges (lime-hating) plants, such as rhododendrons, azaleas, etc. grow best at pH levels below 5.5 (because the pH scale is logarithmic, a one unit drop represents a tenfold decrease, so pH 6 is ten times more acid than pH7; but pH 5 is 100 times more acid). Calcicoles (lime-loving) are generally found on limestone soils, where the pH is above 7.0.

Lawns are slightly complicated. Normal utility lawns (which are often comprised of only perennial ryegrass) like a neutral to slightly alkaline soil (pH6.5 to 7.5). However, if the turf contains luxury grasses (as most do), these prefer a lower pH of about 6.5.

Persistent moss is often an indication of a too acid soil.

Making a Thatch Sandwich - Part 2

I have just top-dressed the lawn. If you read this, you will see why:

We have seen that reducing lawn thatch can be achieved by:

• minimising thatch and mat production
• enhancing the natural breakdown of thatch and mat
  

MINIMISING THATCH AND MAT PRODUCTION

• remove mower clippings
• avoid high doses of nitrogen feeds during first half of season - slow steady growth seems best
  

I don't want to deal with cutting and feeding here. These have been referred to elsewhere.


ENHANCING NATURAL BREAKDOWN OF THATCH AND MATT

• reduce acidity
• use organic nitrogen feeds
• improve aeration
• control water content

Natural breakdown is undertaken by micro-organisms in the soil. Enhancement of this process is achieved by producing an appropriate environment.

acidity
We have already seen that the lawn has been limed to reduce acidity.

organic nitrogen feeds
Using nitrogen feeds in ammonium form (and feeds which can be easily converted to ammonium (e.g. urea)) rather than in nitrate form greatly helps the build up of micro-organisms.

aeration
Aeorbic micro-organisms (which are beneficial to our purpose) need oxygen to function. Pricking the turf facilitates this. Tining and hollow-tining has the same effect.

water content
Micro-organisms need the thatch to be damp if they are to break it down. They cannot work on dry thatch. Pricking also facilitates this. Top-dressing also helps to prevent the thatch from drying out.


TOP-DRESSING

Making the sandwich
Top-dressing involves covering the thatch surface (after raking) with a layer of soil - mixed with sharp sand and organic matter - which is worked into the turf and levelled. This helps prevent the thatch and mat from drying out, allows it to be attacked from both top and bottom (since it contains micro-organisms), and levels out any hollows.

Effectively, a new false soil layer is created, kept open by the sharp sand (not builders' sand). The organic matter (use of this is optional; it helps improve soil structure) can be garden compost sieved through a 1/4 inch sieve. The soil can be garden soil, also passed through a 1/4 inch sieve. The mixture is applied at the rate of about 1 to 1.5 kg per sq metre (about 2.5 to 3.5 lbs per square yard). Apply two or three times as much if you have hollow-tined.

Although it is easy to buy top dressing, it is better to make your own if possible. This way you can adjust it to suit your lawn conditions. For example, for a heavy, poorly-drained clay soil, you could use about 75% sand. On the other hand, a sandy soil might only need about 20% sand. It's up to you. You have much more control.

To level the surface, drag a straight piece of 2 inch by 4 inch timber over it, once you have applied the dressing.

• If your soil is really heavy, hollow-tine or deep-tine first, then brush sandy mix into holes.

• Always make sure that the dressing is worked in: Do not leave it on top of the grass.

• This job is best done when both the grass and the dressing are as dry as possible.

Top-dressing not only levels the surface and improves breakdown of thatch and mat; it will stimulate the grasses to produce new side shoots, thus thickening the turf.

Making a Thatch Sandwich - Part 1

Ask most gardeners what lawn thatch is, and they'll tell you it's a layer of loose dead material on the soil surface comprised of old leaves, dead grass and other miscellaneous rubbish collected over the years. Furthermore, the way to deal with it is to give a good hard raking (with a hand rake) in the autumn and, 'Bob's your uncle', problem solved.

Really?

I wouldn't like to tell you just how hard I raked my lawn, blisters and all. Barrow loads of dead material. But no good. Problem still there. It took years to discover why.


JUST WHAT EXACTLY IS 'THATCH'?

Yes, my lawn did have a loose layer of dead material. And this could be removed quite easily. But I was always frustrated to discover that I could never see the soil surface; I had imagined that if I raked hard enough, this would eventually show through. No. All that was there was a dry corky substance.

I don't know why I didn't think of removing a divet of turf (probably because I always thought it would disfigure the lawn). However, when I finally did, I could see quite clearly that this corky layer was about 3 cms (over 1 inch) thick. And it wasn't only comprised of old leaves - it contained dead and live wiry rhizomes (underground stems) twisted into a dense mat. No wonder I was getting nowhere with the hand rake.

A mechanical raker helped somewhat. But unfortunately there was virtually nothing left of the lawn. Yes, it seemed to recover (though I doubt that all lawns would recover without re-seeding). But it looked awful for much of the year. And the problem never seemed to improve.

Now I am trying a new approach:

• minimise thatch and mat production
• enhance natural breakdown of thatch and mat
  

This way, the lawn can be kept looking as good as possible for much longer.

So, to recap, the term 'thatch' is confusing. Apart from loose dead material on the surface, there is often a dense mat beneath the surface, which is much harder to deal with.

Getting the Light Right - Part 3

Choosing the Window Sill

Window sills make ideal growing platforms, provided a few things are considered:

• Light
• Humidity
• Temperature
  

Light
It takes a very brave plant to face the world on a south-facing sill, especially from late spring onwards when the sun is becoming strong. Only pot geraniums, of the pot plants I possess, are able to withstand the intense heat and low humidity; they are adapted to do this. Nevertheless, even these plants suffer in mid-summer - they too would prefer some shade during these days.

Conversely, few plants can tolerate the low winter light levels of a north-facing sill. I find this position ideally suited to cyclamens, especially in a cooler room. North-facing sills are better if they receive some morning and evening sun. This greatly increases their usefulness.

Both east and west-facing sills are good and will each accommodate a wide range of plants.

Turn the plants daily
The only problem with window sills is that the light is uni-directional, so plants always grow towards it. For this reason, they need turning either each or every other day to keep them growing upright. However, provided this is done, things are fine.

Humidity
Radiators positioned beneath windows should be turned down if we wish to grow plants near them because they lower humidity levels too much, thus drying the plants. Since plants develop stronger at lower temperatures, it might be best to turn off the radiator completely.


Temperature
In winter, it is important that delicate plants are not left too near to the glass when it is freezing outside. Leaving the curtains open is a big help here, since temperatures can drop rapidly after dark behind heavy curtains.

Window sills make ideal spots for small propagators, which can be used to get seeds and cuttings off to an early start. But it is necessary to watch out for the sun. Cover with fleece or half-thickness kitchen roll, so the plants get light but not heat.