it's simple. You are really well protected by law in this kind of situations. If they send you a picture of one high quality plant first and decide to deliver a really weak one next, you have the right to return the plant within 14 days. Also the payment service providers can help you with getting your money back. Creditcard providers and paypal can do this until about 45 days after payment.
Do not forget, you are not the who has to do the work. By law the webstore has to provide evidence he DID send the quality he promises on his website in case of a conflict.