Composts for propagating, watering tips, spring salads, updates on another trial and mustard green manure
I am always trialling different composts and its certainly worth seeking out a good one. West Riding multipurpose has been reliable over many years, but sadly it is only available at a realistic price (£6 per 40 litre bag) when you buy a pallet load. It is based on peat which is sieved out of reservoirs.
Comments on the forum have highlighted the danger of propagating with composts such as New Horizon which are simply too variable. Its a risk we cannot afford, losing precious time and space undercover, sometimes a whole sowing. If peat-free composts contain too much unrotted wood, it sucks nutrients away from seedlings, until its decomposition is finished.
I have had success with using my own compost, but it needs time to prepare it. Firstly I pull out larger pieces of unrotted stems such as brassicas, then (as long as it is dry enough) I use a fork to break up lumps, before passing it through a wide-mesh sieve of chicken wire.
The same procedure works for two year old manures, preferably from animals bedded on straw. However the suffering broad beans in the photo below are a result, I suspect, of too many nutrients in the manure. Probably I should have mixed in about 10% coarse sand, which helps with drainage too. Air is a vital ingredient and is the strong point of peat, whose fibres hold an aerated structure around roots. I think this is why I and many others have struggled with John Innes No. 1, based on dense loam of variable quality; its expensive and you are better sowing into something lighter, or with some sand or vermiculite added.
Further options are to add trace elements such as seaweed, rockdust, wood ash and volcanic lava, see photo of basil below. I bought a sack of fine lava dust two years ago and cannot now find a source to buy more: it is much finer than rockdust and gives more food to pot plants in particular.
Trialling composts for lettuce
This is an experiment I ran in 2011 to see how four plants of Mottistone lettuce, sown in June, would grow in pots of different composts.
1 Green waste/municipal with many woody pieces
2 West riding multipurpose
3 18 month old cow manure (straw bedding), sieved
4 18 month old home-made compost, sieved.
Mottistone has freckled leaves with plenty of green between. So any leaves showing pink are short of nitrogen, which is needed for green colour and leaf growth. You can see this in the green waste compost where decomposing wood is pinching the plant food, for a long time, until three months later the lettuce starts to show green as the wood is mostly decomposed and allows, even releases, nutrients to reach the lettuce.
The multipurpose compost gives fastest early growth, which is what we want when raising plants for setting out after a month or so. Then its nutrients run low, that is normal. I am fascinated to see how the home-made compost grows the largest lettuce after three months, thanks to its store of slow-release nutrients.
The growth of lettuce in pot 4 highlights the value of what we do when spreading compost in the garden, which offers both life (fungi, bacteria, microorganisms) and plant food steadily, over a long period, without its nutrients being leached by rain.
Depending where they are, every two or three days is often enough at this time of year, and less in damp conditions. This was demonstrated when I went on holiday recently and was away from my garden for two weeks. Before leaving I watered all the greenhouse seed trays and module/container plants, and left two small windows open for continual ventilation through the middle of January.
On my return the seedlings and plants, unwatered for 15 days, were all fine. And their compost did not even look dry, except for some larger kale and lettuce plants which were in relatively small amounts of compost for their amount of leaf. They perked up after watering.
Water in the morning, preferably before a bright day, so leaves can dry before nightfall. But plants in a heated house do need more water.
Salads, veg to sow now
Seed packets are not the best place to find advice on sowing dates, for example most packets of salad seeds advise sowing from spring until late summer, but not all are suitable for spring sowing, even when they come up and grow. Harvests of brassica salads (rocket, mizuna, pak choi) risk being small before they flower, and with flea beetle damage on their leaves. If you sow chicory, endive and chervil in spring, they tend to flower before hearting, because May to early June is their natural time to flower. Wait until mid June to sow them and until late July and August to sow salad rocket, mustards etc, for bigger pickings and over a longer period.
Best salads to sow now (strictly undercover) are lettuce, peas for shoots, true spinach (which is different to leaf beet), spring onion and radish, as in the photos. For extra flavour and colours, sow small amounts of sorrel such as Buckler leaved, orach, tree spinach, dill and flat leaved parsley.
Vegetables to sow in early February – well I would wait until mid month.
Lettuce is the spring salad of choice and choosing a mix of varieties gives extra taste and colour. I am wary of commercial mixes as I find they usually contain some varieties that flower too quickly. I aim for my February/March sowings of lettuce, planted out in March and April, to crop for at least ten weeks, until July. Varieties such as Grenoble Red, Bijou, Navara, Freckles and Maravilla di Verona are good for picking weekly over a long period. Avoid Green and Red Salad Bowl, I find they crop for three or four weeks only.
While I was away for two weeks, pigeons discovered a taste for my perennial kale. They like eating at height, and ignored (so far) the land cress growing beside it. So I am setting up some net covers, as on the purple sprouting which is already protected.
On my indoor chillies and arrowroot I have infestations of aphids, so its a chance to try the wood vinegar I found at the King’s study project in Thailand, made from distilling the vapours while making charcoal. It smells of antiseptic and I diluted it 10:1, we shall see.
For the chillies I cut off almost all green stems to leave a woody skeleton, plants staying frost-free in the conservatory until going to the polytunnel in May. They are Jalapeno and some are two years old.
Three strip trial
For two years I have run this comparison of three strips 2x9m (6.5×29 feet). In January 2013 they all started as pasture with dandelion and creeping buttercup, and were different like this:
1 Dug, no compost
2 Undug, mulched polythene Jan-May, no compost
3 Undug, mulched polythene Jan-May, 5cm (2in) old cow manure.
Total harvests in 2013 were 41kg, 40kg and 62kg respectively, from June plantings. Digging gave better early growth as the air from cultivation helped achieve quicker breakdown of weed and grass roots. Then bed 2 caught up in the autumn, while bed 3 was abundant throughout and gave highest yields of most vegetables. There is a chapter on this year of contrasts in my new book.
By spring 2014 I was finding it difficult to maintain enthusiasm for the uncomposted beds 1 and 2. It was feeling like my time spent planting and harvesting was less rewarded – Homeacres is a market garden and time-efficiency is important. Steph helped me both decide and to spread two inches of municipal compost (with food waste) over strips 1 and 2, as well as dividing all three strips into more manageable four foot beds. So now we had this:
1 Dug (in February), 5cm (2in) municipal compost
2 Undug, 5cm (2in) municipal compost
3 Undug, 5cm (2in) old cow manure spread November 2013.
Total harvests in 2014 were 63kg, 75kg and 70kg respectively, from plantings of mostly the same vegetables as in 2013, with minimal rotation. It was fascinating to see the difference made by adding compost! Also in 2014 the dug soil tended to underperform, especially with salads and leeks, whereas there was little difference with both types of beans and brassicas.
Mustard green manure
One part of the experiment has a strip of mustard (Synapsis alba) which we sowed in early September after harvesting the winter squash. It grew well on all three beds, I ate a few of the shoots both in salad (but they are hairy, like radish leaves) and then the plants started to die after some -6C frosts in December.
I think there will be almost no green on the stems by early March, when I shall rake them off to compost. Then I need to spread this year’s compost. Another option for composting would be to spread an inch or so of compost in September, after sowing the mustard in shallow drills, so that after raking off its stems in late winter there is a good tilth for sowing and planting.