Posted: 30/05/2012 at 12:12
Tina, my greenhouse has both, a paved path up the middle and gravel beds either side though on the North wall side I now have permanent staging and a warm bed with cable buried in sand and a thermostat. Above that there are shelves at various heights to take the plants not needing the full warmth, heat rises so they get a nice snug warmth around them. A curtain of bubble wrap round the warm box keeps the seeds and seedlings at the correct temperature.
The other gravel bed is for the tomato's peppers and chili, all in pots I never use grow bags after a calamity with bad compost years ago, filling my own pots I can see what goes in and the watering is better controlled. As the previous poster says I fill all the watering cans and even a couple of buckets leaving them in the green house to warm up for next day and also put moisture into the air, dry air is not good for plants.
A couple of points Tina, not all seeds need the same temperature for them to strike some need to be cool others want around 18 degrees or even more in some cases that is why I have a thermostat. Read the packets.
You do not fill the staging trays with gravel an inch will do nicely to hold the water, if you top the water to the top of the gravel this will give the plants a nice atmosphere around them, it also lifts the pots high enough to let some root grow through into the gravel so they pick up water as needed.
Having experimented with shading for years I now leave it off using extra vents in the greenhouse and if needed a cold fan. The door is open most of the day and the vents as needed plus the fan to move the air, extra buckets of water also help keep the temperature more even.
We all have to learn and most of us admit to still learning even now well past retirement so ask your questions, there is always some one who knows.