\begin{tikzpicture}[node distance = 3cm, auto]
  \node [start] (init) {Make a regular or stiff starter};
  \node [block, right of=init] (feed_new_ratio) {Mix \qty{1}{\gram} existing starter, \qty{5}{\gram} flour and \qty{25}{\gram} water};
  \node [block, right of=feed_new_ratio] (next_day) {Wait\\ \qty{24}{\hour}};
  \node [block, below of=init, node distance=4cm] (feed_again) {Feed again using 1:5:25 ratio};
  \node [block, right of=next_day, node distance=5cm] (test) {Check starter readiness?};
  \node [decision, below of=next_day, node distance=4cm] (ready_signs) {Sour yogurty smell and bubbles visible on flour?};
  \node [block, below of=test, node distance=4cm] (last_feed) {Feed one last time};
  \node [success, below of=last_feed, node distance=3cm] (bread_dough) {Make bread dough};
  \path [line] (init) -- (feed_new_ratio);
  \path [line] (feed_new_ratio) -- (next_day);
  \path [line] (feed_again) -- node{repeat 3 times} (feed_new_ratio);
  \path [line] (next_day) -- node{after 3~days} (test);
  \path [line] (next_day) -- (feed_again);
  \path [line] (test) -- (ready_signs);
  \path [line] (ready_signs) -- node{no} (feed_again);
  \path [line] (ready_signs) -- node{yes} (last_feed);
  \path [line] (last_feed) -- node{after \qtyrange{6}{12}{\hour}} (bread_dough);
\end{tikzpicture}