Terriccio for potted plants

Claudia Image
06/01/2009 - 05:56

My Italian landlord was pleased to see that I filled the terracotta planters (big low wide bowls) with flowers, and reached in to see what I used to plant them in--and shook his head (negatively) when he saw that I used 100% terriccio.  He explained that it is too acidic, and that I should have mixed it with regular dirt from the campo (which is extremely clayey here is my part of Italy).  Likely his preference would have been to use strictly dirt from the field near the olive orchard....I am from the USA and I had always been told that potted plants should not have regular dirt, but only potting soil.  I'm curious to know what others recommend.Also, soon I will need to feed the plants, and I am used to products purchased in the USA (Miracle Gro).  What product should I purchase here for potted flowers such as petunias and geraniums?  I also have basil plants growing in terriccio in a pot.  Any tips for keeping them growing abundantly all summer and fall is appreciated!  I am not an experienced gardener of any type. (This is my first posting--I hope all goes well tecnically....my apologies if not.) 

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Hi Claudia, welcome to the community, I use a mixture of soil (mostly clay) and compost, either bought, or from our own compost heap.Seems to work well, but needs waterering once or twice a day. Nip out the tops of your basil plants before they start to flower and they should last longer, but I have various pots of it all at different stages just to keep us going. I just buy the little plugs in the market and keep potting them up.I do the same thing with flat leaved parsley.A

To my knowledge potting soil is a balanced medium which should be ideal for potting up most plants. The only benefit I can see to adding soil is that you may get better water retention. In my experience petunias are at their happiest in potting soil alone. You could always throw in a few granules of slow release organic fertilizer every now and then and remember to dead-head them!

Hi ClaudiaIn Italy they sell a special terricio for gereniums.  It is basically terricio with the addition of perlite to facilitate water retention and prevent compaction.  Terricio is difficult to re-hydrate once it has dried out, so before planting I normally give it a good soaking and does not let it dry out in the pot.  You can use Compo's terricio universale which already has perlite added to it.  Most other brands of terricio universale do not contain perlite.  To improve drainage and prevent compaction I normally add a little bit of "argilla" which you can find at any builders' merchants.  Builders normally use it to insulate chimneys and fireplaces!  It is a very light granular material and it works for me.  I also add some organic granular fertilizer at planting time and follow up with Compo liquid fertilizer.  Geraniums do not like it wet so I am normally very careful with the watering!  A small piece of broken terracota vase on top of the drain hole at the bottom of the pot also helps drainage. In the UK there are two types of potting compost:  John Innes compost that is soil-based and the peat-based compost like terricio.  There are many grades of soil-based compost depending on what you require the compost for!  You can add soil to normal terricio but my instructions (from my past instructors at a UK local agricultural college of courses that I attended on horticulture) were that you should sterilise garden soil before using for potting.  It is obviously a sensible precaution to prevent the transfer of soil-based diseases to your pots. As the name implies terricio universale can be used for most potting.  When I use the Compo brand of terricio for petunias I add a few granules of water retaining gellatine crystals to it.  This improves the watering retention capacity of the terricio and allows you to water less frequently.  I do not add the crystals when potting geraniums for the reason I mentioned before.  When I surf the Internet for these crystals I always end up on an American site! It must be a very popular product in the USA! I normally bring the crystals with me from the UK.   I have not seen them in Italy, except in the odd florist shop when water and colour have been added! Now that Amazon delivers to Italy from the UK and their other European sites I shall explore their sites for availability.  The crystals are essential if you want terrific hanging baskets around the house! As for your basil, which requires a lot of water and nitrogen to grow, I would keep the soil moist at all times and I would feed it with green plant liquid fertilizer.  Do not forget you can grow tomatoes, cucumbers, courgettes (marrows) in terricio in pots or you can grow them in a terricio bag on the terrace.  "Growbags" were very popular in the UK at one time.  Basically you lay the terricio bag flat and cut out a large rectangular piece out, add you granular fertilizer, water the terricio and add your plants.  The secret is to keep the soil moist and to feed regularly.  Keep the tomatoes separate from the others, as tomatoes require a different kind of fertilizer, which you can get at you local shop. In the past when I have used this method I used the terrico in the following year in the kitchen garden to enrich the soil.  In the UK I use Phostogen for general plant feeding, apart from tomatoes.   I like it because you cannot overfeed and it is very cost effective.  I cannot get it in Italy from the shops!  I can only get it from BAKKER an Italian Internet garden site.  Again this is something that I will be exploring Amazon for.  When potting acid-loving plants likes Azalea terricio universale will not do and if you are using soil then do test for the PH. Forgive me, I know I have gone on a bit but I hope you find the information useful and happy gardening!

 An excellent post from Serge with plenty of good advice. I know that your neighbours would say that it is not necessary to use terricio, but I prefer to do it. Good drainage is always the big secret and you have to be careful about this. On the other hand, terracotta pots will help with this, while plastic ones may be a problem. And they are much nicer to look at.

In reply to by Gala Placidia

Thank you for the quick answers.  My head starts to swim with all the possible products I should get.....and it seems perhaps I made a mistake of potting TOGETHER petunias and geraniums.  Seems they have different needs, perhaps not too compatible.  My petunias, BTW, are doing MUCH BETTER in this terricio than the geraniums.  All I have done is plant them and water them.  No food/fert of any sort yet. Well....we 'll see how they go...and I will look for some food soon to give them.  I did put lots of broken pottery in the bottom of the pots for drainage...so, perhaps that will go well enough. Serge, thanks particularly for your detailed, thoughtful advice.  I really appreciate it a lot.