The architects behind the Marble Arch Mound have hit out at criticism of the new London attraction.
The mound - which opened on Monday - has been slammed by visitors who have branded it a "slag heap" and "the worst thing in London."
Customers looking forward to visiting the £2m attraction hit out on social media and said the attraction resembled a level on the Mario 64 game or the hill from the Teletubbies.
The mound, which sits on the edge of Oxford Street and promised sweeping views over London from its panoramic platform, situated 82 feet and 130 steps up, opened on Monday but closed just three days later, with visitors promised refunds.
Organisers said the Mound would be a "park-like landscape of grass and trees" which was supposed to give visitors "striking views of London and the park" and a "new perspective of Marble Arch itself.
MVRDV - the architects behind the Marble Arch Mound - have hit back at the criticism it has attracted and blamed the country's challenging weather and how "unpredictable" it can be working with plants and trees.
The company assured those wanting to see the mound that "it will get better."
A spokesman told the Architects Journal: "It is a pity the mound opened too soon. It is always unpredictable when you work with plants and trees, especially in challenging weather conditions. Because of the recent drought the sedum appears brown and thin - but it will get better.
"It is a vulnerable installation, no doubt, but we just need to give nature a bit of time. The mound is designed with not only summer, but also fall and winter in mind; it is meant to have an overall green appearance during the time the installation is in place.
"We choose to bring plants to this part of London for a reason: we think that it is symbolic for where we need to go in the future, greening the city.
"The more plants we add to inner cities, on roofs and in streets, the lower the heat island effect will be and the better the city will be able to deal with rising temperatures. Marble Arch Mound symbolises this wish and we are inviting everybody to see for themselves [from next week.]"
On Wednesday, in a fresh blow to the architects, City of Westminster Council said it was clear the man-made mountain was "not ready yet" and has apologised for the delay and offered new tickets to those who were supposed to visit this week.
The authority said it would be working to resolve issues “over the next few days”.
A council spokesman said: "We are aware that elements of the Marble Arch Mound are not yet ready for visitors. We are working hard to resolve this over the next few days.
"In light of the delay, we are offering anybody who has booked a visit during the first week a return ticket free of charge so that they can enjoy the full experience including the Lightfield art installation, M&S Food, and the landscape once it has had time to bed in and grow.
"People who visited the Mound today, and people who are booked for the rest of the week (including the weekend), will be contacted and offered a refund and a free return ticket so they can see the Mound at its best.
"Anyone who has booked a visit this week can go up the Mound as planned and then still take advantage of the free return ticket. The Mound is a living building by design.
"We'll continue to adapt and improve London's newest outdoor attraction and resolve any teething problems as they emerge.
"We're sorry for the delay and look forward to welcoming visitors when they're ready to enjoy all the Mound has to offer. See Tickets will shortly be in touch with everyone who booked a ticket for this week."