Posted: 30/12/2015 at 20:33
Peanuts, disregarding the annual varieties, rudbeckias need more moisture than echinaceas. the former grow well in good rich soil. Echinaceas will grow in light sandy soil IF enriched with plenty of compost and watered well now and then during the summer.
rudbeckias are hardier and will cope well over winter in good moist soil whereas echinaceas will likely rot in those conditions.
Rudbeckias, for me, will grow in some shade. Echinaceas need full sun
however, always best to grow according to your conditions.
Peanuts, whatever you grow improve that sandy soil. Very few perennials will enjoy pure sand.
try agastaches.........they will love warm free draining soils that have some added goodness. Salvia patens will be fine there. Penstemons. achilleas. Argyranthemums. Loads more including lavender, convolvulous cneorum, santolinas, artemisia powys castle, dianthus
so...no to rudbeckias. Yes to echinaceas if you do 3 things......grow them on in pots before planting them out. Get plenty of compost and some dried manure in the planting hole. And plant in a slight recess to enable generous watering every now and then.
Oh! And don't let flowers develop too early. Let plants make good growth and then allow to flower after mid summer.