Last year we built our hothouse (See it here) and for the most part it worked really well. We had early tomatoes (they grew phenomenally), capsicums and cucumbers and were able to get seedlings up earlier for planting out when the weather warmed up.
As we were away for much of the winter we needed to have a hothouse makeover day to get everything going again. We used this opportunity to make some improvements using found and recycled bits and pieces.
The fairly flat roof rain allowed water to form pools and the weight of the water would cause the plastic to droop. Each day after rain we would have to push the plastic up to empty these pools, and this would create a waterfall of water running down the side (which could soak someone if they were too close). We solved this problem by stretching chicken wire tightly across the roof under the plastic. This supports the plastic and prevents pooling of water. An added advantage is that the tightness braces the whole structure preventing it from wobbling so much in strong winds.
We have also added guttering on one side to collect rainwater. This is fed into a 44 gallon drum and allows watering cans to be quickly filled with fresh rainwater which is preferable to using dam water.
We have finished planting in the hothouse and have rotated plants so they are not in the same spots. We have 6 tomatoes, 12 capsicums, 2 eggplants, 4 climbing cucumbers, 12 basils, 2 lemon grasses, 2 perennial climbing chillis (from last year) and heaps of lettuces. We also have numerous plants and seedlings in pots.
Having a hothouse is particularly good this year as it has turned out to be quite a cool start to spring. At least we should be able to get some early vegetables on to our table, even if the cool days continue.