[sussexmike]

My newly acquired allotment is adjacent to the northern perimeter fence.  I'm considering planting a few hazel trees up against the fence.  Would the trees rob the rest of my patch of important nutrients?  Would the roots invade the rest of the patch making it difficult to grow vegetables?

[Yorkie]

Welcome to the site 

Looking at wikipaedia, hazels grown in this country are of a variety which can reach up to 15m in height, although 3 - 8 m is more common.

I would have concerns about the spread of the roots as the trees grow.  They will certainly compete for moisture and nutrients, and it will prove more difficult to grow veg such as spuds and root crops as you will have to dig through the tree roots to harvest etc.

I have two hawthorn trees on my allotment and struggle a little with their roots.  It depends partly on how big the rest of your allotment is, and whether you can afford to give up the space.

[aelf]

Part of the hedge enclosing my plot is of hazel, the rest is hawthorn and blackthorn. If you can keep the hedge down to a manageable height (say 5 feet), the roots are not much of a problem and seem only to extend about 3- 4 feet out from the trunks. The main consideration (for me anyway) is that hazels are fast-growing. Once established, mine put on at least 6 foot of growth a year if left unpruned. The hawthorns are much the same but they do a fair job of deterring the theives and encouraging small birds onto the plot so I love em!