Quick Answer:

What are the essential seed terms for greenhouse gardening? Understanding common seed terminology is key when planning your greenhouse garden. Heirloom seeds are stable, open-pollinated varieties that grow true from saved seed, while hybrid (F1) seeds are lab-created crosses offering traits like disease resistance or high yield but cannot be reliably saved. F2–F5 seeds are later generations from hybrids, gradually stabilizing into your own heirlooms. Pelleted seeds are clay-coated for ease of planting, especially by machine, while treated seeds are coated with chemicals to resist rot in cold soil—something many organic growers prefer to avoid. Terms like “new” may refer only to catalogue listings, not to truly new varieties. You’ll also see micro-tomatoes, compact plants ideal for greenhouses, and days to maturity, which are useful for comparing growth speeds across varieties but are not precise. Ultimately, buying seeds in bulk from fewer suppliers or saving your own seed helps manage rising shipping costs while still offering variety and value in your greenhouse garden.

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So much to consider

It is December and the seed catalogues are arriving fast and furious. Meanwhile, online suppliers are pounding out dozens of notices to remind us it is time to order seeds soon.

Growing Soil with Hügelkultur

When I moved homes and built a new greenhouse, I was in for quite a surprise. The natural soil on my new lot is sand. Pure, yellow sand. This means it drains really well. It also means it does not hold nutrients to feed my plants.

Quick Answer:

Want to kickstart your greenhouse garden this season? The best time to begin is now. Cool-weather crops like arugula, bok choi, spinach, and radishes thrive in early spring greenhouse conditions—even in unheated spaces. Warm the soil with heating cables or IRT mulch to speed up germination and enjoy a head start on the growing season. Greenhouse gardening in late winter or early spring also means fewer pests, like flea beetles. While heat-loving plants like peppers need more warmth to sprout, starting them indoors on a damp paper towel can ensure strong, healthy transplants later. With the right timing and a simple crop schedule, your greenhouse can produce fresh greens and veggies year-round.

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Schedule Your Greenhouse Garden Now

Showing off my arugula (also known as rocket) on Instagram leads to a lot of questions about my greenhouse and what I currently have growing. 

Quick Answer:

What are the tips for greenhouse gardening in March and April? Early spring greenhouse gardening involves starting fruit cuttings like raspberries over heat mats to encourage rooting, transplanting hardy crops such as peas for early harvests, and directly sowing cold-tolerant seeds like radishes, spinach, and arugula in unheated soil. By managing space, timing crops carefully, and using seasonally appropriate strategies, gardeners can extend their growing season and enjoy fresh produce well before outdoor gardens mature. This approach maximizes greenhouse productivity while creating a rewarding, year-round gardening experience.

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Sunshine on Your Face in the Greenhouse Garden

I close my eyes as I bask in the sun, heat on my face. I take off my jacket and then my hat. My neighbors, friends and family have gone away to Martinique, Belize and Spain but I am experiencing the best holiday. I am sitting in the sun at home – in my Greenhouse Garden.

Pests, Worm Castings and Algae

What are Worm Castings?

Before we get to greenhouse gardening algae, let's talk about a shopper on Amazon that complained about bugs in her worm castings. If you don’t speak garden lingo yet, worm castings are simply worm poop. They are mixed with soil in garden beds or in pots to make tomatoes grow faster, stronger and healthier. And just in case you missed the memo, worm poop comes with bugs of its own. The good ones.

Greenhouse Growing is Planning for the Future

I am eating a lot of Kale and Bok Choi from my cool Greenhouse Garden right now.  The winter-sown spinach is suddenly starting to explode as the days get longer too. There are still a few beets and carrots in the greenhouse and the season of overlapping crops is about to begin.  This is a normal life with a greenhouse growing.

So Many Tomatoes, So Little Space

Greenhouse tomato growers are rightfully confused when they see so many kinds of greenhouse tomatoes for sale. Karen Olivier, an independent tomato breeder from the Secret Seed Cartel, estimates there are 20,000 kinds of tomatoes listed right now and she is adding to that number by breeding new tomatoes every year.

 

Quick Answer:

What Are the Best Tips for Soil Amendments & Nutrients in a Greenhouse Garden?
Optimizing greenhouse soil requires building “super soil” by blending quality soil-less mix with compost, biochar, and worm castings, plus adding essential nutrients like nitrogen, phosphorus, potassium, calcium, and micronutrients through amendments such as seed meals, lime, kelp, and gypsum. Recognizing nutrient deficiency signs—like purple leaves from low phosphorus or brown spots from potassium shortage—helps timely fertilization and soil management, ensuring healthy plant growth and improved crop flavor. Regular soil amendment and fertilization tailored to plant needs foster vibrant, productive greenhouse gardens year-round.

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Importance of Soil Amendments & Nutrients in Greenhouse Gardening

A few years back my greenhouse tomato leaves were purple, yellow and spotted. Not all at once, but over time and on different leaves. It was the second year I was growing in my greenhouse and the commercial potting soil I bought was low on phosphorus, nitrogen and potassium. The leaves on the plants were telling me what was going on. And it didn’t look good.

Quick Answer:

How Can Warming Soil Help You Rush the Growing Season and Speed Up Crop Growth? Warming soil with electric heating cables prevents freezing, creates a heat reservoir that radiates warmth to plants, and accelerates seed germination and crop growth, enabling gardeners to start hardy and heat-loving crops earlier in the season for faster, more productive harvests.

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Is patience a virtue?

Some gardeners wait for the sun to gently warm the soil before they start their garden. Others are impatient.

Quick Answer:

How Do I Grow Arugula in My Greenhouse From Seed to Salad?
Arugula is an easy, hardy winter green that thrives in cool greenhouse conditions, reseeds itself naturally, and requires minimal pest control with simple mesh covers in spring. Growing your own arugula lets you enjoy fresh, flavorful leaves and edible flowers all winter long, perfect for salads or toppings. Understanding its growth cycle helps you maximize harvests and incorporate this nutritious green into your seasonal meals confidently.

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My go-to recipe

My potluck arugula salad is sprinkled with jewel-toned tropical pomegranate seeds. My neighbour Barbara is excited and quickly tells me how much she loves the bitter taste of arugula. So I tell her I grow arugula as a winter crop and now she is all ears.