Container gardening: 12 mistakes I made

Last year, we were living in a cottage that had zero garden. It was in the middle of nowhere and literally all we had was a space the size of a standard apartment balcony around the back door. In that space, we had to be able to store our bins as well as hang out our washing.

I started container gardening in March 2020, having previously had a “regular” garden at our house in England. I started most of the plants from seed, with the exception of trees.

Gardening for me has always been a process of making mistakes and learning from them for next time. When something works first time, I am amazed. Here are the mistakes I made and what I learned from them:

Never plant out too soon

A lot of packets of seeds say “plant out when risk of frost has passed” but they don’t tell you that’s a proper gardening date that varies based on your region. You can find out your last frost date by searching for it. If you really can’t find out, don’t plant out until after 20th May in the UK.

If you plant out too soon, the night temperature will be too cold for your young plants to handle and they will freeze to death.

Move new plants into bigger pots when you get them

I bought some trees, including two lovely dwarf cherry trees and a raspberry bush. They were from different garden stores and arrived separately. The trees were very obviously in need of bigger pots when I got them, so I put them straight into the big containers they have lived in for the past year.

The raspberry bush came in a 5 litre pot and even though it was quite a big plant I didn’t think it needed planting up into anything bigger. So I left it.

This was not a good plan. More on the raspberry next.

Don’t put hardy outdoor plants beside a radiator that’s hotter than an active volcano

Worried about protecting my raspberry plant from frost, I’d read that raspberries won’t crop if they get too cold in their first two years, so I decided to keep it indoors until May. I popped it on the deepest windowsill in the kitchen. It honestly didn’t occur to me that being next to a radiator would cause any problems. Our heating was badly-controlled and was only on or off, it had no thermostat (this was a rented house). When the heating was on, the heat from the radiator rose into the air and killed half of the raspberry plant (you can see it in the picture for this article, it’s the plant with yellow and brown leaves sat on the white plate).

Don’t listen to well-meaning but badly-informed people about plants, especially if they are not container gardening

I put the raspberry bush outside, still in that 5l pot. Its leaves turned white and then brown, and my aunt told me that it wasn’t a bush at all and I needed to separate the “canes”. So I dug it out and, stupidly, pulled the plant apart trying to save it, until I found out it was all attached and had one main stem beneath the soil. If it hadn’t already been dead I would lose a lot of sleep over this.

Cress on kitchen towel needs watering 3x daily

I was really excited about growing cress as it can be done indoors with no special know-how (allegedly). It’s aimed at children so how hard can it be, right? Wrong!

Cress dries out (like, the paper towel shrivels up and goes hard) about 2-3 times per day. It needs so much nannying and constant attention that it really only works if cress is the only baby in your life.

Unfortunately, I have a human baby to look after, so time after time my cress dried out and died. I got it to crop a grand total of once without it immediately drying out and dying, and that was scattered over soil, not on kitchen roll. I ate most of that. I haven’t really mastered cress or other microgreens very well.

Pick your veg when they are ready

I bought pea seeds that were advertised as ideal for container gardens. I planted 4 in a big pot and put them outside. They grew perfectly. I hadn’t counted on needing to stake them and so they grew sort of curly near the soil until I sorted that. They never got very tall, and I’d expected them to reach 2-3 feet (bearing in mind regular pea plants can easily reach 6-ish feet or 2 metres-ish). Pea pods grew and went fat and green but they were tiny. Maybe 4cm across.

I thought they were still growing, not quite understanding that dwarf plants mean dwarf crops. So I left them. They turned yellow then brown and died. I picked them at that point and even tried one. It was bitter and inedible. I should have picked them when they were ready instead of waiting for them to look like full-sized pea pods.

Echinacea doesn’t grow easily in Ireland

Echinacea is a coneflower native to North America. I wanted to grow it because when the pandemic hit, the shelves were emptied of echinacea tea by all the sensible people who know about its immune-boosting properties.

It is really hard to get it to grow in Ireland especially if you follow the instructions on the packet. It has taken me 8 attempts to get one to sprout, then it immediately died, and two more attempts to get one to live a month (and counting).

Don’t assume seeds will be easy to get next year

I also successfully grew chamomile, another of my favourite tea-herbs. I got a bumper crop in a 60cm trough, enough to last for months if I’d cut and dried it. When our rabbit Timmy died, we buried him in a hedge, and we planted the chamomile on his grave.

It’s always been a readily-available plant in the shops and online, it never occurred to me that would be the last time I’d see a packet of chamomile seeds. But it was. I would have brought the perennial plant to our new house if I’d had any idea about how hard it is to get chamomile in Ireland these days.

It’s okay if the soil goes moldy

The first time my propagator got a layer of white mold over the surface of the soil, my seeds (broccoli microgreens) hadn’t sprouted yet and I threw the lot away. The third time it happened, I left it alone and the seeds grew through fine.

Now I understand that if I’m covering a plant pot or propagator to keep seeds warm, it’s a fact of life that the soil will go moldy before the seeds sprout. I haven’t done anything wrong.

You will need more containers than you think

I couldn’t grow all the things I wanted to last year because there wasn’t enough space in the kitchen to start them off (I had nowhere else to do it), and even if there had been, there were no containers to put it all in. In the UK, all the garden centres got emptied of their stock las year due to fear of food shortages, and I was lucky to get three containers and two troughs but it wasn’t enough for all the seeds I was waiting to plant.

Small plant pots blow away in high winds

We had several big storms last year and every time, my smaller pots blew away and ended up either on next door’s drive, in the hedge, or completely AWOL. I lost two mint plants, a sunflower and two broccoli because one rowdy wind storm began overnight. The storm was so bad it actually brought the wall down next to where my plants were standing.

In the morning I had to walk around searching for my plants, putting them back into pots and sitting them on my storage bench again. A thyme plant sadly died from all of this. I’m not sure what the best answer is, but now in bad weather I move all my pots up against the house, using the bigger containers to form a protective palisade around the little ones.

The baby plants were indoors for longer than I expected

This one doesn’t apply if you buy everything ready-grown from a garden centre or nursery, but if you grow from seed, it will take 15-60 days for them to germinate, then they have to grow big and strong enough to go outside and the risk of frost must pass and some plants have to slowly acclimatise to outside over a series of days or weeks!

On average, plants started from seed lived in my kitchen for 2 months. This made it impossible to do successive planting and I’ve had the same issue this year (but less stressful as our house is double the size of the old one but places to put plants are still limited due to having a curious toddler on the loose).

Bonus tip: Cut microgreens and cress with scissors if you don’t want to eat soil/other weird stuff.

So that’s the twelve (actually 13) things I learned from container gardening last year. The plants were in my house much longer than I’d expected due to living so far north. That alone helped me plan my gardening for this year a lot more effectively.

Overall, last year’s experience with container gardening has made me a more resilient problem-solver when it comes to growing food. When I discovered in February that our new, huge back garden was a waterlogged heavy clay soil which was terrible for gardening, I wasn’t phased, and have switched to a raised bed and a bunch of containers for this year’s plants, because it was too late (and lockdown has closed down everything) to adjust the soil in time for this year’s growing season.

I think every gardener could benefit from learning how to do container gardening.