At this point in the season, maintenance is the goal for keeping your greenhouse productive now and in the coming month.

Despite the snow at the beginning of June, the plants in your greenhouse should be growing rapidly.

I would recommend keeping an eye on the following potential trouble spots: air circulation and fungal problems.

When the doors and ventilation systems in the greenhouse are closed due to cool, rainy or snowy(!) conditions, the lack of air circulation can cause an outbreak of fungal disease. Usually this shows up as white mold on the soil.

The remedy for this is cultivation of the soil around the plants. With some plants, tomato plants for instance, you can increase air circulation around the plants by pruning some of the lower leaves of the plant. Remove only leaves up to the first cluster of flowers or fruit.

At the same time as you are evaluating your tomato plants, check to see whether there are enough flowers or fruit developing on the plant or are you just getting an excessive amount of greenery (leaves, stems and suckers) without an adequate amount of fruit?

If very little or no fruit is developing, you may have an excessive amount of nitrogen in the soil and not enough phosphate or potassium, which are the ingredients the plants need for fruit and flower production. To remedy this, add bone meal, rock phosphate or wood ashes which are all natural products.

If using chemical fertilizer, another dosage of 20-20-20 may be in order.

Your cucumber plants should also be growing quickly. If the plants are left on the ground or on top of the benches, check that the fruit is not lying in water inviting fungal disease.

Most cucumber plants like to grow up a trellis which gives the plants good air circulation. It is also easier to see and pick the vegetable. It is a bit more maintenance to keep tying your plants to a trellis, but to do so is more efficient.

As soon as the cucumbers have started to develop, they need huge quantities of water. We grew our cukes in 12-inch deep benches and, when we watered mature cucumber plants, the amount of water running out the bottom of the bench was not just a drop or two but more like a miniature waterfall. The cucumbers loved this treatment and grew quickly.

Other tips for greenhouse maintenance are:

  • Control weeds, especially on walkways and under benches.
  • If you’re growing corn, pollinate daily as soon as the tassels show.
  • If you’ve planted lettuce and radishes, they may be ready to harvest before the really warm weather of July makes them mushy.
  • Check pepper plants often for signs of insect problems.
  • Once green beans start to flower, give those lots of water, but try to keep foliage dry.

Having a maintenance schedule for your greenhouse keeps you up to date as to what’s happening among your plants.

It is fun to see the plants as they develop rapidly under favourable conditions and just the thought of that first ripe tomato or the juicy vine-picked cucumber makes all the effort worthwhile.

Ingrid Wilcox operates Lubbock Garden and Floral Consultant and offers gardening, greenhouse and flower arranging workshops. Contact her at [email protected]

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