Post offices offer Simplified procedure and Ordinary procedure for customs clearance

When we pay taxes on imported parcels at our place this is called the "simplified procedure". There is a second procedure called "ordinary procedure". In most EU countries when the value of the parcel is or seems to be above 150 eur, or when the plant importer has to register as a professional ( because of frequent imports of plants to the same address, or large parcel, or high value ), then the procedure

is called ordinary : with this " ordinary procedure " importers have to pay taxes at a customs center of the post ( it may be far ) either directly or by hiring an agent, indeed during an ordinary procedure the postal agents are not allowed to open the parcels and take the customs documents directly ( invoice and phytosanitary certificate ) : the importer or customs agent ( broker ) must do it and handover the documents to the post. http://www.correos.es/ss/Satellite/site/informacion_cliente-tramites_aduaneros-inicio/includeTemplate=COR_DetalleGuiasAyuda-sidioma=en_GB
Most " small parcel air " ( parcels up to 2000 gr ) are delivered by the simplified procedure , but EMS parcels that seem to be of 150 eur value are instead more likely to be delivered through the ordinary procedure. Dividing an import in several parcels is a good solution.

 Herbs and Spices, Hoya, Hoya seeds, Orchid seeds, Ferns, Fern spores are for sale on aleyagarden.com Plant care is available in various posts of this blog. Contact : aleyagarden@hotmail.com

Para importar semillas y plantas de vivero es necesario presentar una solicitud o una notificación

The buyer protection policy enforced by PayPal encourages people to import plants by shifting on the exporter the risk that their customs may intercept the package whenever the import is deemed a professional one ( for commercial propagation ) hence needed registration prior import in addition to the export documents ( phytosanitary certificate and CITES if endangered species ) sent by the exporter with the parcel.

In most cases the exporters of live plants cannot guess if the customs will consider the parcel as a professional one or not, except when rules are made public on the internet like in USA, or reported by hearsay such as those of Italy, where the number of plants ( 12 and 5 ) per week and per address are the limit before prior registration of the importer. ( however customs can see as an abuse the repetitive imports of legally correct numbers without prior registration and delay the clearance or find a sanitary pretext to justify an interception  ).
On the contrary in Spain * for instance ( and also probably in Russia ) there is no maximum number of plants and customs consider case by case the frequency and number of plants to determine if the import needed a registration prior import. Hence the post may request from the buyer Phytosanitary certificate AND Spanish authorization to clear at customs and say on the postal site that "documents are missing" if this latter Spanish authorization ( import permit ) is not provided by the buyer. But the buyers may argue in a Paypal claim for non received goods that they were requested a missing phytosanitary certificate;  when in fact what can be missing is any of the two documents. 
In a Paypal claim for non received item due to reported lack of phytosanitary certificate the senders can always prove that they made a phytosanitary certificate as they have copies.  If the buyers had done a registration, they should also present a copy of the document. Failure to provide such document when the exporter has a copy of the phytosanitary certificates should always rule in favor of the exporter.
Plants cannot be returned in their original state and a great part of the cost is production and administration for a stock maintenance : even if returned live, individual plants are discarded.
The rule that money and goods cannot be on the exporter's side should not apply with live plants for their export to be sustainable. At Aleyagarden we inform on the check out page where customers confirm their purchases that importers must know their import rules and practices and that live plants cannot be returned in their original state or cannot sustain a non as described claim with Paypal; we emphasize again this information in home page of aleyagarden.com, conditions of sale page, this BlogSpot, and Facebook page.

* Para importar semillas y plantas de vivero es necesario presentar una solicitud o una notificación
previa a la importación .. : http://www.asaja.com/files/horizontales/08072013134233_Manual%20importacin%20semillas%20y%20plantas.pdf