Once you decide on having a greenhouse, the next thing you will concern yourself with, is planning the foundation. It is a lot easier with ready-made greenhouses, because those with their own floors can be laid on most types of ground surfaces. But if you choose to DIY it, you will have to prepare the ground beneath it first.
Railroad ties are good for this. They can be spaced an inch or two apart and should form a reliable foundation. You can also create a simple platform with 2 x 4 feet or 1 x 6 feet slabs nailed to 4 x 4 feet slabs spaced out around 18 inches under the greenhouse slats. You do need to watch out for weeds and mildew, and maybe replace the floor boards every now and then.
Laying a concrete foundation is the next step for DIY greenhouses to avoid soil contact. This will be a semi-permanent structure that will be difficult to remove later on when you don’t need the greenhouse anymore, so do keep that in mind. You need to lay out the area, and build a temporary “container” around the area where the concrete will be poured on; remember it needs to be level and smooth.
Building a concrete foundation can take a couple of weekends. These days, all the materials, tools, and any construction plans can be ordered online. There are advantages to having a concrete foundation. For one, it is sturdy and gives you some options concerning the heating of the greenhouse.
You can overlay the concrete with carpet or tiles, and underneath them, you can have heating tubes and other wiring. The concrete foundation can then absorb/reflect heat in the greenhouse, and is easy to maintain. You may also wish to overlay the concrete with a pebble mix for a great décor finish, although this is harder and more expensive to get done.
Creating the concrete foundation is best carried out in moderate to warm temperatures, low humidity and no rain, so that the cement can dry, so plan ahead and make use of the local weather forecast. The concrete floor needs to be strong enough to support the weight of all the tables, benches, and pots; you don’t want to replace the foundation once everything is set up.
Once the foundation is planned out properly, you can then move on to the watering system and think about adding any electrical accessories to your greenhouse.