Shopping Basket

Grow Bags vs Pots and Borders

Monday, 13 December 2021  |  Matt

plants growing in pots and raised beds

Which is best? Pots? Grow bags? Greenhouse border growing? This handy guide will lead you through all of the important factors to consider when deciding whether to grow your greenhouse plants in pots, grow bags or border growing.

Growing in the Borders

The main benefits of growing in greenhouse borders are:

  1. The roots of your plants will have the opportunity to grow and spread out endlessly.
  2. Your plants will be fine if you forget to water for a few days. Even tomatoes can survive a couple of dry days if you grow in the greenhouse border.
  3. Greenhouse borders are more forgiving and allow for flexibility in your planting. You can successfully do things like underplant cordon tomatoes and force early carrots if you plant in a border.

The main drawbacks of growing in a border are:

  1. Some plants such as peppers (both hot and sweet) will produce more foliage in a border which may decrease plant health and yield.
  2. Pooling water can be a disadvantage when growing cucumbers in a border. This can be prevented by simply watering to the side and mounding the base.
  3. Often it is difficult to predict the optimal level of fertiliser needed for your plants.
  4. It will be necessary to complete the arduous task of changing the border’s soil each year to avoid any diseases.

Related reading: Best Vegetables to Grow in a Greenhouse

Growing in Grow Bags

You will find many benefits to growing your plants in a grow bag including convenience, low prices, space-saving and ease of use. The grow bag is simply a plastic bag that holds the compost. The compost will not lose water through evaporation and therefore can be used as a soil improver at the end of the growing season.

Prices of grow bags have decreased in recent years but so has the quality and quantity of the compost in the bag. It is often necessary to shop around in order to find a high-quality grow bag with enough compost. Alternatively, you could combine two bags together by cutting the top off one and the bottom off another to combine them into an extra-large bag and add your own compost.

Check your grow bag for markings for cut-outs. These markings will show you the best places to plant. Typically you will see markings for three plants, I suggest cutting that number to only two for better quality.

I will not argue with the obvious convenience and low price of ready-made grow bags, but I still prefer to make my own by filling reusable grow bags with my favourite compost mix. I find I have better success with the larger bags and the higher quality compost.

If you are making your own grow bags it is important to note that grow bag compost may tend to hold water better and have more nutrients added as compared to a general multi-purpose compost.

filling pots with compost

Growing in Pots

Similar to grow bags you can find pots in several different sizes. The size of pot you choose will depend on the type of plant you are wanting to grow. For sweet and chilli peppers a small pot works well. You will want to look for 20cm (8”) pots. It is easy to stack pepper plants and grow them in smaller spaces because they don’t grow tall.

If you are growing cucumbers in pots remember to give them space to trail. Smaller varieties such as Picolino, Zeina and Cucino will thrive in small 20cm pots, but larger cucumber varieties such as Carmen or Tiffany will do better in a border or large grow bag. If you want to grow large cucumbers in pots, consider using a builder’s bucket or something of similar size. Don’t forget to drill some drainage holes.

Aubergines are similar to cucumbers in that they need a larger container to grow in.

Planting tomatoes in pots work very well. You will want 25 cm (10”) pots for most varieties of tomatoes. Whether you use pots, grow bags or hanging baskets for your tomatoes you can start them in your greenhouse during the cooler months and move them outside for the summer. 

Some of the disadvantages of pots are that they are breakable, they take up a significant amount of storage space and they need washing before re-use.

Read next: Tomato Grow Bags vs Pots - Which is Best?