You might remember the meaning of the character 延 with this easy mnemonic:
In order to prolong your plant's blossom period, stop slashing (丿) the leaves and make sure there is at least a space of one long stride (廴) between each plant. Also, stop (止) watering them every day!
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.