A quick note on bolting

March 18, 2011 § Leave a comment

Bolting is when a plant produces flowers prematurely. In the vegetable garden this is most commonly seen in mid to late summer with plants like lettuce and spinach. Day length and light intensity are natural triggers for flowering in plants and of course lettuce and spinach are cool weather short season (short daylength) crops.

Plants also bolt as a survival mechanism: if they think they are not going to live very long even very young plants will try to produce a flower to produce seed, even if day length is optimal.

Here is a Palla Rossa lettuce beginning to flower. This extending of the central portion of the plant is characteristic of heading lettuce:

Note the following:

Plant is very healthy so not bolting in response to ‘survival issues’;

Bright, sunny day implies mid-summer day lengths …

… we can conclude the person who planted it put it in the ground at the wrong time. I can confirm she did. I can also confirm said plant tasted like an old boot.

As soon as most of the brassica, celery, root vegetables, lettuce and most soft herbs flower proper they lose flavour and texture. Picked within a few days of the first signs of flowering they won’t taste too bad, though in some cases it might be better to leave the plant flower; appreciate its beauty, maybe use a few flowers as garnishes and/or collect seed from it.

The broccoli in the image below is a few days to a week past optimal harvest date- you can see that a few of the florets are about to open into yellow flowers.

Conversly some cultivars have an improved flavour if left to flower- purple chuy sum (a flowering brassica), kailaan chinese stem broccoli and some kales, for example.

Bolt resistant varieties take longer to develop a seed stalk and so focus on vegetative growth for longer, but there is no guarantee that bolting will not occur. Managing environmental factors (see below) will mitigate if not eliminate the likelihood of bolting in vegetable crops.

Watering regularly and shading from the sun is key to keeping cool weather crops happy if you’re growing them out of season. See companion and inter-planting for some ideas on how to create shady conditions in your garden.

A very comprehensive guide to beating the bugs

March 15, 2011 § Leave a comment

I found this on an old memory stick, its a 130 page e-book published in 2005 by the Sustainable Agriculture Network (US based) called ‘Manage Insects on your Farm: A Guide to Ecological Strategies’ (click here to read it)

When I say its comprehensive, I do mean comprehensive. I recall reading it in summer 2006 and feeling distinctly smug to be in possession of such a battleplan.

How to build a polytunnel for (about) £150

February 15, 2011 § Leave a comment

Ok it might end up looking a little ‘Steptoe’, but you’ll have fun building it. I did one of these last year and its still standing, though I am going to rebuild it using more hoops to make it stronger.

Most of the cost here is for good polytunnel polythene- the rest of the component parts can be cobbled together for free.

A nifty way to make a tunnel cloche at home is to cut some long, young saplings or bendy (willow) branches, ideally more than 6ft in length. They need to be a uniform thickness along the length of 1-2” with side shoots removed and the join smoothed over. Soak them in water for a week (wrap in a wet blanket, unless you have a pond) to make them pliable then wedge them into an ‘A’ shape between a space which is between 1.5 and 2m wide- a stepladder is quite good for smaller frames- and leave them dry thoroughly- for at least 1 month.

A quicker option is to use flexible plastic tubing (the PEX type used for plumbing) which can slot directly over the stakes (read on for staking info). Screws can affix the tubes to the stakes to make a reasonably sturdy structure.

Purchase polytunnel plastic or netting (fleece is a cheaper option but tears easily) and anti-hotspot tape or gaffer tape. If your arches are 1m high and 1.5m wide at the base you need to buy polythene which is at least 3.5m wide.

Dig two trenches about 1.5m apart each 30cm (12”) deep and 30cm wide (a spades width). Hammer 60cm (2ft) stakes into the ground 1.6m (5.2ft) apart at 0.75cm (2.5ft) intervals along the outside of the trench. Leave half of the stake above ground. The stakes secure the structure and could be replaced by the sides of a raised bed or railway sleepers. Stakes can be made from offcuts of wood, metal plant stakes, metal pipes or rods, thick tree branches.

You want to put each arch 0.75m apart, so however many arches you have multiplied by 0.75m equals the length of your trench. You just push the end of the arches into the soil to a depth of about 20-40cm (10-24”) next to the stakes. bind them to the stakes for added support. If using PEX tubing slot them over the stakes.

Drape your covering over the structure. Roll up a bamboo cane along either long edge of the plastic and secure with tape. Bury one side of the polythene into the ready dug trench (the bamboo helps to keep it taught and reduces the likelihood of it being blown around considerably). Wedge the other side it gently between the stake/edge of raised bed and the arch. Secure with plenty of tent pegs, specialised polytunnel pegs or smooth rocks and to avoid the polythene tearing put tape at these sites of friction. At each narrow end gather the polythene tightly into a neat ball and tie it with thin rope. Tie the rope to a rock.

When you need to go into your polytunnel you can simply raise the bamboo cane and balance it on top of the structure. To ventilate, untie the bunched end from the rock and re-bunch it and retie it at the top of the structure.

If anyone has a better method (likely) please send it in.

Click here for an excellent link which shows you how to build a full size polytunnel.

Bean trench- Nice idea from the Guardian.co.uk

February 7, 2011 § Leave a comment

Finally something I can do in the garden! My soil is too dam soggy to work it and I’m not going to risk direct sowing just yet.

Lia Leendertz the Guardian’s garden correspondent mentioned a good tip in this weekends paper. I think this would work for most non-root crops. Also this method may impart some heat to the soil for spring sowings. I’d add that its best to chop the waste up really small, else it may not be fully decomposed come spring/summer:

Garden week: Runner beans Photograph: Roy McMahon/Corbis

Bean there

It’s too soon to plant runner beans, but you can prepare for them. They love a moist, fertile root run, and go wild for a bean trench. Dig the trench about 2ft deep and 2ft wide to the length you require, line it thickly with newspaper and water until the paper’s soaked. Chuck your kitchen scraps in, covering with a thin layer of soil each time. The trench works as a mini compost heap into which the greedy, thirsty beans can sink their feet.

How to get big aubergine yields

February 5, 2011 § 2 Comments

It can be challenging to get a really substantial crop from aubergines in the UK so we have put together an extended growing guide (the original can be read on our website here) to help.

Aubergine plants need regular care throughout their lifecycle to ensure plants receive no check to growth- the benefits of this early care will be seen in the harvest weight.

As aubergines need a long growing season, get an early start in March by raising young plants with heat and under glass outdoors, or on a sunny windowsill indoors. Seeds can be started as early as end January as long as sufficient heat and light can be provided. Aubergine seeds should be started no later than April/early May-  better to buy plugs at this time in the season.

Aubergine seeds, along with tomato and chilli seeds love ‘bottom heat’ (i.e from a heated mat, propagator, hotbed or soil heating cables) and will germinate much more quickly and consistently with this provision.

Pot on transplants when they have healthy but not dense rootballs. You can keep potting them on every 3-4 weeks until they go into the ground.

Plant your aubergines into their final growing positions in late April or May- a bit earlier in a polytunnel/greenhouse. Its is not advisable to plant out too early as aubergines grow well in pots but are stunted by cold temperatures and harsh winds.

They should be at least 15-20cm tall when they go into the ground:


Aubergines plants are attractive and look good in flower beds and containers. They grow relatively slowly compared to tomatoes, cucurbits and tall herbs, and in addition they are short plants when mature (maximum 1m), so it is advisable to plant them in or near the front of the bed receiving full sun, and give them plenty of room. The more sun the better for aubergines.


Aubergine plants need as much heat and wind protection as possible and well-draining soil, a sandy loam type soil is ideal.

Container grown aubergines should be housed in pots which are a minimum 30cm wide and 45cm deep. A suitable compost blend for aubergines contains plenty of rich soil, soil aerators and slow release fertilisers.

Aubergines have a deep rooting profile and will benefit from the soil being worked at depth prior to planting. Plant spacing is at least 45cm (18”) for the mini aubergines and 90cm (36”) for large varieties. Leave at least 70cm (30”) between rows.

Loosely tie the plant stem to a central stake to guide growth upwards, if neccessary. Aubergine plants tend to bifurcate naturally but you can pinch out the top of the plant when it is about 30 cm (9”) tall to encourage it to bush out if it does not appear to be doing so by itself.


As the plant matures, avoid overwatering and feed consistently with a general purpose fertiliser until fruits set. As fruits begin to swell, switch to a feed which is higher in potash.

Watering regularly (little and often) is important during fruit maturation. Harvest each fruit as it matures (when still glossy and firm) by cutting the stem to ensure continued fruit set. If fruits lose their gloss they are too ripe and may not cook well- in this case it is best to keep it for seed.

Pinch off blossoms 4 weeks before the first expected frost so that the plant channels energy into ripening existing fruit instead of producing new ones.

Starting seed indoors part 3: Vegetable varieties to start early

January 30, 2011 § Leave a comment

By and large most vegetable crops can be planted when specified on seed packets, outdoors, and they will fare much better than if raised in artificial conditions.

A few varieties can be planted in winter with a bit of help from artificial lighting. There are two main reasons to plant veg under lights in winter:

1. For varieties which originate from parts of the world with longer/warmer growing seasons than in the UK;

2. To achieve two crops of varieties like tomatoes which traditionally are only grown once a year.

Aubergines, chillies, peppers and tomatoes need a long, hot summer to yield big harvests. These plants originate from more southerly latitudes countries with much longer, hotter summers than in the UK.

To achieve big harvests in the UK these plants need to be started in early spring, but these varieties really need heat and good light to germinate and grow well. These conditions occur in about April, but if you sow seed in April the plant will not be ready to fruit until about June/July. This only leaves two months of good weather for fruiting and ripening.

Ideally, come April these plants should be 8 weeks old, so when you plant them outside in May they are ready to flower; this means the plant has four months of good growing conditions to fruit.

I get two harvests of each of these varieties. The first lot are sown under lights in January, begin fruiting in May and crop by July, the second lot are sown in March, fruit in late June and yield in late August/September.

Commercial growers take this one step further and sow seed throughout the year, utilising artificial lights to manipulate the seasons, thus harvesting all year round.

If this is confusing please email!

Starting seeds indoors part 2: Setting up a simple set of lights

January 24, 2011 § 2 Comments

The Sun, is, obviously, immensly powerful. Trying to re-create it in your garden shed is, obviously, difficult.

To re-create the sun, mortal style, head to a well-stocked electrical store.

You need to buy a single or twin fluorescent light ballast – they come in lengths between 1 and 6ft. 2ft double ballasts are nice and manageable and good for windowsills.

This ballast is to house fluorescent tubes. Specifically these tubes should be ‘cool’ spectrum, and 30 to 60W. GE and Phillips both make bulbs suitable for plants. Electrical stores may have these/can order them, and some aquarium shops sell them.

Here are my lights with chillies growing under them. The wall behind the lights is covered in reflective fabric. Note how close the plants are to the bulb- any further away and they will stretch.

You need to fix them up securely as I cannot afford to be held liable for this thing falling ontop of your seedlings/kids/nana/dog.

When choosing a location consider air temperature, ventilation and existing light levels. Basically, the more light the better.

In terms of air temperature, if growing out of season (winter) you may need to provide additional heat in the form of a propagator, heated mat or soil heating cables. The type of seeds which germinate well in cold weather are generally the ones which don’t need artificial lighting- alliums, brassica.  The ones which need the headstart- chilies, tomatoes, aubergines, herbs- need heat to germinate.

Ventilation is very important- plants need air flow to ‘breathe’ and they will stretch and beome susceptible to leaf damage if in still air.

It is useful to purchase a timer so you don’t need to be switching the lights on and off daily- the plants benefit from having consistent ‘day lengths’ also. About 8 hours a day is enough.

Nutrient deficiency information & photo guide

January 23, 2011 § 2 Comments

Here is a really useful guide I use when identifying nutrient deficiencies in vegetable crops.

I have copied it from our business website, where you can find more of my waffle on growing veg.

This data for nutrient deficiencies are from a paper by Wade Berry at the University of California. The images come courtesy of Dr H Bloom and Dr A Epstein from their 2004 paper entitled Mineral Nutrition of Plants: Principles and Perspectives. Dr Berry’s article can be read at:


This article is part of a huge plant physiology database:





Boron deficiencies are most likely to manifest in large heading brassica. Leaves may appear distorted and cauliflower heads stunted, small and bitter with brown patches on them. Borax and organic matter (rich compost) contain boron.




Calcium is used by plants to make cell walls, for root growth, for nutrient uptake and for pollen formation. Deficiency symptoms include browning leaf tips and margins and always occur on new growth. Leaves may curl downwards. Fruit and flower growth may be stunted and leaves may appear twisted. Cabbages, cauliflowers, peppers, tomatoes and celery are most susceptible to calcium deficiency. Liming prior to planting is advised for all of these crops as lime increases calcium levels in soils and raises pH- a low pH can cause calcium to become locked into soils and unavailable to the plant.



« Read the rest of this entry »

Starting seeds indoors part 1: Artificial plant lighting

January 13, 2011 § 2 Comments

The first in a series of three posts discussing starting vegetable seed in winter indoors:

  • Starting seeds indoors part 1: Artificial plant lighting
  • Starting seeds indoors part 2: Setting up a simple set of lights
  • Starting seeds indoors part 3: Vegetable varieties to start early and how best to plant them

Plant lights are used by gardeners- both amateur and professional- to start certain varieties growing before outdoor conditions are warm/bright enough, and also to provide optimal light levels during fruiting (e.g. commercial tomato crops) to maximise yields.

Artificial plant lights used to supplement existing light levels in a polytunnel or greenhouse allow the grower to manipulate day length and light intensity.

Let me explain some fundamentals about artificial plant lighting:

Plant lights are very similar to domestic lighting but the spectrum and the intensity is tailored to meet the needs of plants.

Fluorescent lighting is used largely for its ‘cool’ spectrum outputs, operating in the blue end of the spectrum. These lights are used for seedlings and for plants like lettuce which prefer shorter days with less intense light. Fluorsecent plant lights can be strip light or compact fluorescent lights (CFL’s), the latter look like large domestic energy saving bulbs.

Bulbs which emit from the ‘warm’ part of the spectrum- reds and yellows- mimic summer daylight and induce flowering. Tomatoes and peppers are good examples of plants which need a lot of red and orange light to produce fruit. This light is often supplied by sodium-type bulbs (pretty much the same as streetlights), which emit higher intensity light than fluorescent light.

Cool weather crops bolt in response to a variety of stimuli including day length, light intensity, intensity of red and yellow light, air temperature and soil temperature.

We use plant lights at our nursery to start chillies and sweet peppers in December. These plants have compact growing habits and after reaching a certain height their growth then shifts to concentrate on bushing out and strengthening stems.

As the UK has a less than ideal growing climate for chillies and sweet peppers (and aubergines, tomatoes, sweet potatoes, figs, olives, etc, etc) these early sown plants have a head start on seed sown in spring. They are that bit bigger when planted in the ground (or potted on in readiness for good planting conditions) and tend to ‘pop’ into growth and rapid flowering. The harvest period is extended and therefore there is more to eat.

Pepper and aubergine seeds are notoriously poor germinators when soil is too cold, so controlling conditions extends to supplying bottom heat. This is an important point as you have to remember to recreate other environmental factors, not just the sun, when starting seed indoors- consider ventilation, soil/air temperature, drainage.

See also:

  • Starting seeds indoors part 2: Setting up a simple set of lights
  • Starting seeds indoors part 3: Vegetable varieties to start early and how best to plant them

PS If anyone out there has SAD grow seeds in winter! Its like St tropez in my polytunnel :) I am gardening in sunglasses

My smallest vegetable garden ever

October 22, 2010 § Leave a comment

The smallest vegetable garden I ever owned was in Shoreditch, east London, on the Geffrye Estate.

It measured about 4 x 4m but was amazingly productive. I planned the spacings carefully and planted mostly from plug (not the carrots of course), as seeds may not have been able to compete with adjacent plants.

From front to back:

Interplanted rows of carrots and chervil

A Zapallo Plomo pumpkin

Interplanted row of leefs and tarragon

Sweetcorn with flat leaf parsley at the base (left hand side)

Beetroot and peas/sweet peas (right hand side)


And on the other side of the garden more sweetcorn, lettuce, tomatoes and runner beans:


When you live in central London this is an oasis :)


Here are a few harvest pics .. anyone else have a habit of eating all the veg before it gets chance to be photographed??

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