April VI: the garden at the end of April

April 2017 in NW London has been very dry, pretty sunny and with very variable temperatures (max. maximum 22C, min. maximum 9C, max. minimum 12C, min. minimum 1-2C). With many young plants set out, watering has been necessary, although with most crops I have kept it to the minimum possible.

Apart from the warm spell early in the month, I have kept fleece on my cabbage, spinach, beetroot and turnip bed throughout the month, finally lifting it on 29/04, with excellent results. However, in general, all crops are doing quite well.

Broad Beans are flowering and several plants are now over 4ft high. Sticks and string will be put around them in the first week of May.

Chard is being harvested regularly, but tap water is not as good as rain! Pea shoots are being eaten, but I am still not satisfied with this as a crop: one more year to get it right or something else replaces them!

Lettuces for Pick and Come Again(PACA) are well established, but nowhere near ready for picking. Ten Little Gems for May harvest are progressing OK, with 5 further ahead than the rest.

Onions are further ahead than usual, with the clumps and salad onions looking especially fine. The shallot clumps are well established after an early March sowing.

Carrots sown on 31st March have germinated beautifully, this means I might actually have to thin them. The same is true of those sown on 9th April, uncovered on 29th April and the exuberant radish germination in the drills thinned the same day.

Parsnips sown on 9th April have emerged by 29th April, not yet as efficiently as the carrots but more than enough seedlings for each sown row.

Turnips sown mid March have been thinned to 10cm on 29th April, with some nibbler attacking a few last week. Overall, they are on track for May harvest. The 31st March sowing have just been thinned the second time to about 15cm.

The Boltardy beetroot clumps are the best ever and my Pablo sowings are just developing true leaves in the modules.

First Early Potatoes are all through (18/18), six second earlies have appeared by 29/04 and around 10 maincrop plants have appeared by 29/04. The bags for exhibition were set up on 29th April, 16 weeks before a harvest date around 19th August.

Radish harvest started on 20th April and the first sowing has yielded 12 roots a day ever since. Its harvest should complete for sowing carrots on the May Full Moon. Subsequent sowings will provide harvests through to the first week of June. The 31st March sowing has progressed magnificently under fleece, I do not think I have ever seen happier plants.

The lean to is full currently with:

1. Three trays of Alderman peas – to be transplanted very early in May.

2. Two trays of Pablo Beetroot – to be transplanted mid-May.

3. One tray of Quintal de Alsace Cabbage, to go out in June.

4. Ten 8cm pots with Sorrel transplants – to go in a shady area getting four hours sun a day.

5. A tray with wallflower and lovage transplants in 8cm pots – to form perennials on a shady boundary area with 5-6 hrs sunshine a day.

6. A tray with a borage transplant (for the same boundary as the wallflowers) and chives (for the same boundary).

7. Two 17 litre polypots germinating Sweet Candle Carrots, to be grown for shows.

Inside, all the tomatoes are progressing, although the February plants could do with living outside quite soon. Flowers are on the Red Alerts. The March plants need spreading out soon and the April ones are happily growing in 8cm pots.

Finally, the first leek modules are all now showing seedlings and marigold seeds germinated 24 seedlings with great haste: one for each tomato plant!

I have religiously hoed between and around my plants on appropriate days using my Nunki Weeder. Whether it has helped or not, who knows, but things are looking good.

The blossom on the apple trees, sprayed for the first time with horn manure this February, is the best I have ever seen. We await fruit set with anticipation.

I may be dreaming, but it may just be that horn manure can also help pear trees to resist pear midge (nothing else I have tried has ever achieved it, so that would be a wonderful outcome if it occurs).

One wonders whether a viscious slug attack is around the corner. Very few have appeared due to the drought, but last year, late May/early June was disastrous after a great early season.

It is becoming clear to me that no dig gardening helps in the vegetable garden but is not enough.

Good compost transforms carrot germination and early growth of most spring plants, notably radish, lettuce, turnip and banana shallot. The compost effect works when put down in November, in late February and in mid March.

Watering young plants just enough so they do not die may lead to initial slow growth and good rooting, but it is better than flooding them. Finding the right levels of water for young onions and shallots appears to be an art form……

But the combination of not digging, producing great compost and watering correctly does seem to me the Holy Trinity for effortless effective gardening.

I still feel there is so much to learn, but compared to three years ago, my no dig garden has progressed in leaps and bounds.

April V: doubling the spring radish harvesting season…

Radish is a wonderfully useful little crop to grow in spring, as it will finish harvest by the first week of June, meaning it can be sown and harvested prior to sowing/planting out maincrop beetroot, maincrop carrot, leeks, dwarf beans etc.

Here in NW London, I have found that sowing radish direct before the end of March gives poor yields, so the earliest realistic harvest date for directly sown radish is around May 5-8th.

As I also find that the warmer temperatures see pests eating young radishes, the latest I tend to sow radish direct in spring is around April 20th, giving harvests up to around 8th June.

So, simply sowing outside limits the harvest to about four weeks.

So over the past two years, I have experimented with sowing radish in modules indoors with 160 radish seeds per 40 module tray. With rapid germination, this year I sowed modules on 25th February and transplanted the speedy half on 6th March and the slower growers on 13th March.

I sowed a second batch on 23rd March and transplanted them all on 31st March.

By doing this, I had six rows of 12 modules in a 1*1.5m area.

The aim is to harvest 12 roots a day for 20 days from April 20th, freeing the first five rows by May 7th to allow sowing of four rows of carrot maincrop.

The remainder of the radish season will then come from directly sown rows.

To harvest 12 roots a day (four each for three people) for fifty days means 600 harvested roots. With a sowing density of 200 roots per square metre and 1000 seeds sown, that implies 5 square metres of soil to cover the crop. Whilst this is 10% of my garden, I plant 12 square metres after the end of May with beans and leeks, whilst maincrop beetroot and carrot can follow earlier sowings and parsnip and carrot sown in April can be interplanted with radish too.

A nice way to add healthy bites to the salad bowl in spring.

April IV: Late snow or frosts: how often do they occur?

With stories coming out of Europe from France to Romania of record snowfalls, frosts or both and warnings of crop losses of up to 100% (e.g. vines in some more northerly growing areas in France), and with a northerly blast accompanied by snow and frosts ocurring this week in the UK, it is worth asking how often such weather events occur in Britain and how gardeners should manage risk as a result.

Obviously it depends where in the country you are. I considered snow falling above 1500ft in the Scottish mountains to be situation normal in April when I lived up there in the 1980s and 1990s. The Met Office says that between 1981 and 2010, you could expect snow on 2-3 days in April averaged across the country, so in general this is an occupational hazard when gardening. In 1981, Sheffield had almost 30cm of snow in the last week of April! And as a boy, we had a freak overnight snowfall in NW London in the 1970s which meant I went tobogganing after Easter!

Going back through the records, it seems to me that serious snowfall is a once in a generation event in the lowlands of England in April (1981 the last major event) but frosts and accompanying light snow is more common. This suggests that statistically, if you can protect plants from light frost and snowfall through April, more often than not you will benefit from earlier harvests and the ability to plant two crops a year.

I have noticed the huge benefit of covering the following plants with 30gsm fleece through March and parts of April: cabbage, spinach, beetroot and lettuce. It is also beneficial for successful germination of radish, turnip, carrots and parsnip.

I purchased 25m*2m of fleece from  www.garden-netting.co.uk for under £30 inc VAT and delivery this spring and cut it into 3 lots of 6m*2m and two lots of 3.5m*2m. The 2m width ensures that the whole 1.5 metre width of my beds is covered. 6m length ensures complete coverage of 5m long beds, whereas my 3m long beds or half a 5m long bed can be covered using a 3.5m length.

You will need either a set of bricks, stones or wooden battens to hold the fleece in place – foraging for freebies is worth it as stone/brick will last forever.

The fleece can also be used in the autumn to extend the season and to establish over-wintering leaves well before winter arrives.

But overall, my experiences the past two years with fleece has been entirely positive.


April III: The mathematics of sowing in modules

In order to achieve the yields you desire from your garden, you need to be sure you have enough seedlings planted to generate the number of mature plants you desire. Losing a month is often not an option, so a bit of maths is worthwhile.

The maths goes something like this:

Number of strong seedlings created for transplanting = number of mature plants desired + number lost after transplantation (slugs and other pests, weak young plants etc)+margin of safety due to unforseen events.

Number of seeds to sow = (number of strong seedlings for transplantation/frequency of seed germination)+excess required to eliminate weak seedlings.

Obviously the better gardener you are, the fewer seedlings you will lose following transplantation and the fewer weak seedlings you will create after germination.

However, everyone can be honest with themselves currently, whilst striving to improve in future.

When I started growing tomatoes, I did not get good germination and I lost a few potting up. After four years of saving my own seed, I get 100% germination and almost never lose a plant through potting up. I still retain one spare in 8cm pots, allowing me to pick the best two of each strain.

When using commercial seeds, there is more uncertainty. I have sown two batches of Alderman peas in modules in 2017, firstly in February for shoots, then in early April for maincrop peas. Both sowings have shown a 65-70% frequency of germination and I used that figure when estimating how many seeds to sow to generate 90 seedlings for my 3 metre row. I sowed 160 and 12 days after sowing, 103 have germinated.

The other time honoured solution is to sow two or three seeds per module and thin to the best one as desired.

When creating clumps of seedlings (e.g. for onions, shallots and salad onions), I usually put 6 or 7 onion seeds looking for 5 mature plants in the clump; 5 or 6 banana shallots looking for 4 plants; and 10-12 salad onions hoping for seven or eight mature plants.

The other major issue is season’s beginning or end. When pushing the boundaries, more plants are likely to fail, so more back ups are a prudent precaution. I progressed 10 spinach clumps for eight weeks to ensure I had five successful clumps in the ground by mid April. Similarly, I progressed 15 beetroot clumps from a mid-February sowing to achieve 10 healthily transplanted clumps in mid April.

Every vegetable is slightly different in this regard.

But spending a few years working out effective margins of safety to ensure you have good crops almost every year (there is no plan to counter a freak snowfall in May in Greater London, after all, other than hoping as many plants as possible survive under fleece) is definitely worthwhile.

April II: first sowing of second crops….

Having completed the first sowing of my 50sqm garden, thoughts now turn to getting second crops sown. The first are autumn leeks and cabbage.

The leeks are intended to be planted out around the end of May, once the spring turnips have been harvested. The autumn cabbage will be planted after pea shoots in mid to late June.

I am sowing Autumn Mammoth leeks to harvest from the beginning of November and will sow enough to plant out 3 square metres. I will sow 80 modules with 4 seeds, to plant out 70. In addition, I will sow 120 singles to plant out 80. Whilst these will not be the biggest leeks on earth, there will be around 350 juicy vegetables for winter. The clumps will be planted at 15cm within the row and 15cm between rows. The singles will be 15cm within the row and latticed at 12cm between rows.

The autumn cabbages should give 8 hearts to harvest from November, so I shall sow 12 modules, each with two seeds, and reduce to one as necessary.

  • Easter Sunday is a leaf day, so along with these sowings, I will harvest chard; cut the grass for compost; water the lettuce, spinach, cabbage and spring onions; and pinch out the pea shoots for the first time.

April I: Comfrey Strain Bocking 14 as an organic green manure

Comfrey is a plant recommended by many organic gardeners. Why is this?

1. It grows rapidly and its leaves can be harvested 4 or 5 times a season for many years.

2. The composition of its leaves are reckoned to be almost perfect in terms of minerals for feeding plants.

3. Its leaves can be rotted to produce a concentrated tea, suitable for feeding many plants (notably beans, tomatoes and potatoes).

4. It acts as an excellent compost accelerator and enriches the quality of compost at the same time.

5. Planting potatoes wrapped in comfrey leaves can enhance crop yields.

6. Combining comfrey, grass cuttings and manure can make a perfect hilling up mixture for potatoes.

7. The deep rooting of the plants brings buried nutrients to the surface, as the remaining leaves in autumn are left to die back, creating surface compost.


Lawrence Hills of the Henry Doubleday Association pioneered research into uses of comfrey, identifying Bocking Strain 14 as an optimal strain. It is a sterile strain, which means it does not spread and invade other areas of your garden. It is also very vigorous, giving large yields each season.

If you wish to establish some comfrey, it is a good idea to do this in early to mid summer and not make any harvests until the following spring. Planting your maincrop potatoes when the first harvest of comfrey is ready is a natural way of timing potato planting to natural cycles.

For a fascinating read about Hills’ research on comfrey, read:

‘Comfrey: Past, present and future’, Lawrence D Hills (1976) ISBN 9780571110070