It’s great to hear your tomatoes are thriving – they’re one of the best crops for a home glasshouse in New Zealand’s climate. Other vegetables that grow well in a glasshouse include beans, cucumbers, courgettes, and eggplants. These warm-season crops enjoy the sheltered, warmer conditions a glasshouse provides.
 

Why Your Lettuce and Spinach May Be Struggling

Lettuces and spinach prefer cooler growing conditions, and they often struggle in a hot glasshouse; especially if there’s not enough ventilation. Excess heat can cause spinach to bolt (go to seed prematurely), and lettuce to grow too fast or fail to form a proper heart – particularly with varieties like iceberg.To grow these greens successfully, try:

• Opening vents and doors during the day to increase airflow

• Growing them in the cooler months, or using shade cloth

• Choosing bolt-resistant or loose-leaf lettuce varieties
   

Soil Health in the Glasshouse

If you’re growing directly in the soil inside your glasshouse, it’s critical to replenish nutrients annually. Add compost and a quality veggie mix each season and mix well with the existing soil. Compost improves soil structure, encourages beneficial microbial life and earthworms, and enhances drainage; all critical for productive glasshouse growing.

Try Daltons 7in1 Vegetable Mix, which contains slow-release fertilisers and essential nutrients. If you're growing in large containers, refresh the mix each season with Daltons Premium Outdoor Container Mix to maintain healthy plant growth.
 

Can You Grow Mushrooms in a Glasshouse?

In short, no. Mushrooms prefer dark, humid, and cool environments, which are the opposite of most glasshouse conditions. Instead, mushrooms are best grown indoors or in a dedicated mushroom-growing setup like a dark shed or insulated grow tent with regulated humidity.