HOW TO GROW BUTTERNUT SQUASH IN POTS OR CONTAINERS
Butternut squash are vigorous plants and to get the most out of a container grown crop you will need to make sure that there is plenty of nutrition available to it. Unless you are going to apply liquid or granular feeds - or are going to periodically top dress your container with an appropriate mulch - the only nutrients that are going to be available to your growing squash are those found within the container. If these vital nutrients become used before the end of the growing season then your plant will weaken and your crop can become stunted and lose considerable quality. In addition, you are likely to see an increased incidence in pests and diseases.
Each squash seedling will need to be planted approximately 3ft from its nearest neighbour, so unless you are using something the size of half-barrels you are likely to be use only one plant per container. If you have plenty of seedlings then plant 2-3 seedlings per container with the view to removing the weakest two a week or so after germination.
Having been started off inside under protection, the young squash plants will need to be hardened off for a week or two before they are permanently left outside. If your container is too large or heavy to move then ensure that the seedlings are protected at night by a bell cloche or something similar.
Butternut squash are vigorous plants, and once they start growing, they can spread rapidly. While the plants are still young, you can choose to control the foliage by either growing them vertically up a wigwam or trellis or allowing them to trail naturally along the ground.
Your squash plants will require plenty of water during the growing season – especially in hot weather - so keep an eye on them so that they don’t dry out. If the plant does dry out when there is fruit on the vine then there will be a strong chance that it will shed its fruit as a way of protecting the plant. Be careful too about over-watering too as this can also increase the incidence of fungal rots.
Your butternut squash should be ready to pick in the autumn but remove the fruits before the weather turns cold and definitely before the first frost. Timing is important because if you pick them before they are properly ripe then they can end up lacking in flavour.