Can Alzheimer's affect how someone feels about the outdoors?

Without knowing her complete history, it's difficult to figure out what may be bothering her. But with dementia in general, there's a tendency to lose one's problem-solving skills. Knowing what to do in the garden -- the process of pruning, watering, weeding, and so forth -- may now be problematic. Your mother may still enjoy gardening but may not know how to proceed. Afraid of making a mistake or embarrassed by her confusion, she may find it easier to withdraw from the activity altogether.

It's like a car that's running but stuck in neutral gear. She needs another person to push her into motion. She needs someone to take the initiative to encourage her, but in a way that preserves her dignity as well as her autonomy.

Instead of saying "Can I help you?" though, you'll have to lead her in a nondomineering way. For example, you could say, "I feel like doing some gardening. Do you want to do it together?" To invite a person to participate is a really helpful technique with someone who has Alzheimer's. Quite naturally, it's difficult for anyone to accept the help of others; it's always better if someone asks us to participate.