The first thing to do is study the allergic potential of the species you want to plant and draw up a list of forbidden plants. Each person is allergic to a particular species or group of species, but in general there is a series of plants that cause allergies in many people:

One of the plant groups that cause the most allergies is the gramineae family,� which includes, among others, bamboo and Bermuda grass. Their main problem is that they produce pollen for many months. Except in the damp northern regions of Spain, in this country it is virtually impossible to keep a lawn from sprouting Bermuda grass. So it is a good idea to keep this space to a minimum if there are people with allergies in the family. You can substitute it with covering species such as lesser periwinkle, candytuft or henbit in areas where they will not be stepped on repeatedly. For areas where people will be walking a lot, there are surfaces like gravel which when used properly can look quite decorative and are easy to maintain.

If you still want a lawn, make sure the seed mix does not have Bermuda grass, mow it often, water it more than usual and as fertilizer use enriched peat instead of manure. Since peat is more acidic it favors growth of grasses that are less allergic. Furthermore, such peat is sold free of unwanted seeds.

Another problematic family are the cupressaceae. Pollen from cypresses and Arizona cypresses is highly allergic. The attractive look and cultural aura of cypresses make them hard to replace in Spanish gardens, but this is not the case with their Arizona relatives, which are almost always used in large quantities to form thick hedges. A climbing species is just as efficient, easier to maintain, takes up less space and adds an element of color thanks to its changing foliage or flowers. If you want a more compact hedge, you can use species such as laurel, cherry laurel, laurustinus or cedar.

Other problematic trees are olive, birch, willow, holm oak, ash, lime, alder, oriental plane and poplar. The last two are troublemakers both for their pollen and their fruit.

Dry weather aggravates allergies because it makes pollen float more easily. So keeping your garden damp will help. This can be done quite pleasantly with sprinklers, mist producers, shady areas and use of fountains or small ponds.
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