Agriculture Reference
In-Depth Information
The most critical parameter in the tunnel in the early spring is not heat but light.
Polythene film transmits slightly less light than glass even when it is new, and
the transmission falls off a little each year as the film becomes more porous.
While this is insignificant at other times of year, in early spring a cold frame or
small greenhouse is very valuable. Even if heat is provided, without adequate
light seedlings will quickly become leggy and feeble, so if you are unable to provide
a bright environment elsewhere it is usually better to wait for a few weeks until
the light level improves.
As spring continues the potting benches in the tunnel gradually fill up, both with
hot-weather seedlings for the polytunnel and with early starts for the outdoor
plot. A capillary bed (see Chapter 6,
page 49) will prove invaluable because it
provides water from the roots upward, saving time on watering and reducing
losses from damping off (a fungal infection, common in warm, crowded and wet
conditions, that wipes out whole trays of seedlings with astonishing speed). As
seedlings become ready to plant in the outdoor garden, plant a few of them in
the tunnel as space permits, to stretch the harvesting season. Broad beans, for
example, will be ready three weeks earlier in the tunnel than the same seedlings
planted outside, and will be a very welcome addition to your diet during the
hungry gap.
Summer (mid-April to late September)
Hot-weather crops grow fast once the weather is warm and will need training.
This year's harvests will begin very quickly, starting with salads and 'first early'
potatoes and followed by broad beans, kohlrabi and strawberries. Even after
chillies and tomatoes have been planted out and potted on, the potting bench
will remain crowded with seedlings for outdoor use, safe from predators and
late frosts. Cucumbers should finally make it into the tunnel beds some time in
June and will grow strongly after a couple of weeks' settling in. Once they get
going they will need almost daily attention to keep them from sprawling away
from the supports.
By July things will be in full swing and the harvests of tomatoes, chillies, cucumbers
and peppers should have begun, even in indifferent summers, and flowers will
appear on the melons. The tunnel should feature some visible flowers to help
attract pollinating insects such as hoverflies (which are likely to snack on aphids
while visiting), and with luck they will be followed by a toad or two to help keep
slug numbers under control.
In August the first melons will be ready (although in colder years these may be a
little delayed), but it is now, at the peak of the gardening year, that some plants
should be taken out. This is to make room for the next phase of planting in
preparation for winter and the hungry gap.
