Gardening is humbling because you can do everything right, and things still don’t work out. A late frost. A mysterious disease. We’ve all been there. Yet, in the 30 years I’ve been gardening, I’ve actually learned the most from my mistakes.

Here are the gardening gaffes that taught me hard but critical lessons.

• Being wowed by a photo

My first gardening project was sprucing up my entry, inspired by a Sunset magazine photo of bougainvillea clambering up a house. How hard could it be? I planted a 1 gallon bougainvillea with magenta blooms right next to the front door.

I watered. I waited. I marveled at its astonishing growth. (I must be good at this!) It kept growing and growing. I snipped and clipped and bound branches, but I was no match for its “Jack and the Beanstalk” tendencies. Then its razor-sharp thorns appeared. Yeow! Soon, I looked like I’d lost a catfight, and I had to warn visitors to be careful.

Lessons learned? Know a plant’s ultimate size, growth habit and other nuances before planting. And don’t plant up against a house, as this is not a fire-smart move.

• Using a planting hole as a dog dish

Being hard-headed, I didn’t let this experience deter me. Instead, I got to work in the backyard, where I intended to plant a shrub.

I dug in, which wasn’t easy. Why was the soil so hard? (Do I need a new shovel?) I persisted, finally excavating a hole and filling it with water. I waited. I watched. My Labrador drank from that hole all day, and there was still water that evening. No matter, I wasn’t going to let a little water get in my way. Besides, didn’t plants love water?

Unlike my wretched but speedy bougainvillea, this plant didn’t budge. Its leaves drooped and yellowed. I watered more, but it didn’t heal my ailing patient. In fact, it got worse, and died.

It’s no great mystery why this shrub met an early demise. I drowned the poor thing. Plants need good drainage, so roots have adequate air around them.

My clay soil was rock hard and held water like a cup. I quickly learned there are two choices: choose plants that thrive in clay soil or add organic material to boost drainage.

• Getting lazy with weeds

Small weed patches I’ve ignored have almost always turned into bigger challenges. I’ve learned always to keep a few pieces of cardboard handy to quickly place over weedy spots. Layering compost and mulch on top simultaneously snuffs out weeds and builds soil. To me, cardboard is as important a tool as a trowel.

• Underestimating uninvited guests

We gave our daughter a cherry tree for her fifth birthday, which we promptly planted. We never plucked a cherry off that tree, however, because deer annihilated it that first night. The best thing to come out of that snafu was a 6-foot fence.

• Planting tomatoes in March

Oh, those spring months, bursting with visions of bumper crops. One year I couldn’t hold back: I planted tomatoes early.

Turns out tomatoes don’t grow in cold weather or soil, and are even more susceptible to disease in cooler conditions — not to mention susceptible to frost. Until the soil reaches at least 60 degrees, the plants will not perform. Yes, I could try row covers or other warming tricks, but I don’t like messing with garden accouterments.

Today, I wait till May 1 to plant tomatoes, and I’m diligent about using a planting calendar for all edibles.

• Pruning too little, too much, or too wrong

I’m embarrassed to tell you how many misshapen and failing plants I’ve removed due to inept or non-existent pruning. Unless you want to hire someone for the job, I strongly recommend learning the basics. The Marin Master Gardeners have a terrific website and videos that explain correct pruning techniques. Do yourself a favor and tune in.

Sponsored by UC Cooperative Extension, the University of California Marin Master Gardeners provides science- and research-based information for Marin home gardeners. Email questions to helpdesk @marinmg.org. Attach photos for inquiries about plant pests or diseases. Please phone 415-473-4910 to see when a Master Gardener will be at the office. There is a sample box outside the office so Marin gardeners can drop off samples 24/7. Visit our events calendar to attend an upcoming gardening workshop at marinmg.ucanr.edu/ASK_US/EVENTS">marinmg.ucanr.edu/ASK_US/EVENTS. Subscribe to the Leaflet, UC Marin Master Gardener’s free quarterly e-newsletter, at marinmg.ucanr.edu.