Category: Polytunnels

De-leafing is one of the tasks that beginners to tomato-growing have to learn.  It’s a simple task, and knowing why you need to do it makes it easier still.  Basically, you take the lowest leaves off single-stemmed vine tomato plants as they grow upwards.  It’s harder and less profitable to do it on bush-type plants with their smaller leaves and tangled growth habit, so just cut out any dead or diseased bits and otherwise leave them alone.

Only the leaves on the top 75 centimetres of vine tomatoes contribute to their growth and yield: the rest are passengers using up feed and water.  The lowest leaves are the oldest, most tired and shaded ones that contribute nothing.  They are magnets for fungus diseases such as Botrytis (grey mould), and increase the risk of infection of ripening tomatoes by trapping damp stagnant air around them.  They can hide weeds and slugs that make things worse again.

There are two ways of de-leafing.  In the morning, when plants are still pumped up with water drawn up during the night, the leaf stem will snap off cleanly if bent sharply upwards at the base.  The neat wound left behind will be dry and resistant to fungal infection by nightfall.  The easiest way to break off leaves is to place your fingers behind the main stem opposite the leaf, and your thumb on the leaf stem about two centimetres above the base, then pull in your thumb smartly towards the main stem to break it inwards.  If it hangs on to the stem by a bit at the top snap it downwards to finish the job.  Cutting works too, but the stubs that you leave behind can rot and infect the main stem. Compost the leaves, and wash your hands thoroughly.

Winter greens

You could pull out the last of your summer crops from your greenhouse, clean it up for the winter and close it until spring.  But why not have it produce fresh green salads for you all winter?  If you didn’t sow any leaf greens in recent weeks you can still sow turnip seed in early November and expect the soil to be still warm enough for some growth.  It will grow slower than would September-sown crops but still be worthwhile.

Failing that, you can plant roots of turnip and beetroot in pots or the greenhouse soil and let them sprout leaves as if it were next spring.  The leaves might not be as good eating as the seedling ones but will be better than nothing.  The roots may need some frost to trigger this re-growth.  Watch out for slugs.

Chicory has traditionally been grown for forcing in winter.  Dig up straight roots about 2cm thick, cut the leaves back to about 2cm high and shorten the roots to about 15cm.  Store them flat in sand in a cool shed.  Every few weeks, plant a half-dozen or so roots upright and tight together in a medium pot of damp compost, placing it in a shady part of the glasshouse and covering over the top with an upturned pot (cover the drainage holes) to exclude light.  Darkness makes the emerging leaves paler and less bitter.  Cut them for eating when about 15cm high.

Rhubarb roots can be forced too.  Dig up crowns and leave them exposed to frost.  Then pack them tightly into a container with old compost, leaving them upright.  Put it in a shady part of the greenhouse covered with black plastic.  Harvest the sticks when still small and dump the exhausted roots afterwards.

August is the latest month for taking semi-ripe cuttings.  Fuchsias, Pelargoniums, evergreens, perennial climbers and most deciduous shrubs can still be propagated now, if you use the warmth of a glasshouse or tunnel to boost their growth.

Choose non-flowering shoots or cut the flowers off.  Cut off slips 7-15 cm long by cutting just below a node (the thickening on a stem where a leaf or side shoot grows outwards).  Clematis does better when cut between two nodes.  Alternatively, tear off a side shoot of the right length with a piece of the main stem still attached like a foot, and cut off the ‘toe’ leaving the heel.  Remove any leaves that would end up buried below the surface.  Take plenty of cuttings: some won’t grow and the tighter they are crowded together the better they root.

Fill a container with a mix of two parts peat or leaf mould to one of sand, and water it well.  Dip the bases of the cuttings in hormone rooting powder if you want, and lower them into holes dibbled around the edge with a pencil or similar.  Firm the compost in well to ensure good contact with the cuttings.

The cuttings will lose water through their leaves and wither unless kept in the shade.  Place them under solid staging, or rig up a shade above them.  Use tinfoil or white plastic instead of black plastic, and keep it up from the plants to prevent heat build-up.

Lay clear plastic over the cuttings to keep in humidity.  Hold it off the plants with hoops of wire or similar.  Pelargoniums and plants with grey, silver, silky or hairy leaves resent humidity and are best left uncovered.  Check the cuttings regularly and remove any dead bits.  They are ready to pot on when they start growing.