Your Harvst greenhouse is a unique, controlled growing environment; partly cold frame, partly greenhouse … with the addition of automatic cooling in the summer and optional heating in the winter. What you can grow depends on where you put it, what model you have and what time of year you’re planting.
Where to put it
Plants love the sun, so try to put your mini greenhouse / cold frame in a position where it gets as much sun as possible. In the height of summer, this will be hot – but unlike a greenhouse the Harvst mini greenhouses fully open up to ventilate all excess heat. You can also fit shades if you have sensitive plants inside. In the winter, spring and autumn, the black backing will soak up the warmth to keep the temperature up and extend your growing season.
Make sure you fix it to something solid. The Harvst greenhouses are light, and will get blown around in a strong wind
The growing environment
All Harvst greenhouses have multiple growing levels. The “Yard” model (shown on the right) has two shelf tiers, and the “Terrace” model has one. The shelf width is adjustable, to fit whatever growing container you use.
In the bottom, you will either grow directly in the soil, or in containers on a hard surface such as brick or concrete.
The shelves will have containers with shallower soil, and the bottom will have deeper soil – which determines which plants you can grow.
Both the top and the bottom have built-in self watering, which you can set to different schedules (timer, temperature and/or moisture driven).
The upper watering is provided via misters which give a fine spray of water; designed to keep soild and young seedlings damp. The lower watering is via sprayers which can deliver more water, if needed. Misters and sprayers are removable, so you can fit dripper lines if you want.
The lid opens automatically when the temperature reaches 20 degrees C, so that your plants don’t cook in the summer. Our greenhouses are unique in the amount of heat they can vent – the large fully opening roof helps keep the temperature down in the summer. If you have a crop which wants a warmer environment, you can adjust the opener.
If your mini greenhouse is connected to the mains, you can add heating and grow lights, which is covered in more detail here.
Growing in containers
Standard seed trays (38 by 23 cm, 15″ by 9″) are typically used for starting seedlings off, which are later transplanted to deeper soil. These would sit on the top shelf of your Harvst greenhouse. You can fit more seed trays on if you put them “portrait” but you’ll get less sunlight on the tiers below.
You can either fill the trays directly with soil/compost, or use cells or modules within the tray. We recommend using the deep seed trays to give you plants long root runs and as a robust container for modules or pots.
Large grow tubs
If you’re not growing on soil, you’ll need large containers in the bottom. Harvst mini greenhouses have been designed to fit 600×400 mm Euro crates, which are strong, roomy containers ideal for plants that need deeper soil. We like the ones 220mm (about 9″ deep) and sell these grow tubs with drainage holes in our shop.
Crops such as beetroot, chard, spinach, tomatoes, kale, carrots grow nicely in these tubs.
What about seasons?
Here in the UK, most plants go to sleep over winter, or simply don’t grow at all. They need a certain amount of light, and a minimum temperature to germinate, flower and fruit. There’s no point trying to grow tomatoes in December! Detailed information on what plants to grow at what times of year is beyond the scope of this page, so we’ll focus on how your Harvst greenhouse can help.
The back of your seed packet (or the seed company website) will give you guidelines for when to plant. When they say “plant indoors” they expect that your house is warmer than the outdoors; the seeds will need this warmth to germinate. Early in the season (before April in the UK) an unheated Harvst greenhouse is unlikely to be warm enough to germinate these seeds. If the seed guidelines suggest planting outdoors, you can typically do this up to a month earlier in a mini-greenhouse due to the extra protection it provides.
Just as you get more growing time at the beginning of the season, your plants in the mini greenhouse will provide extra warmth and protection later into the autumn.
In late winter you can start some seeds directly in your greenhouse. You can also move out the seedlings which have germinated indoors, to harden them off (or for growing on fully in the greenhouse).
Now’s the time when everything really gets going. Most seeds will germinate happily in the mini-greenhouse, and your winter seedlings will be growing fast.
You can expect non-stop crops of salad, spinach, spring onions, carrots, radish and more. Don’t forget to do succession sowing so you don’t have any gaps.
Things will be slowing down now, but there will still be crops of salad and leaves. If it’s an indian summer, then you might still get another crop or two of fast growing plants before the temperature drops.
Top shelf / seed tray plants
Any seeds that need to be started in a tray or cells will begin their life on the top shelf of your mini-greenhouse. Once they have reached a suitable size for transplanting, you can move them down to a large tub or the soil at the bottom, or even outside.
Middle shelf / medium tub plants
You can transplant seedlings from the top shelf seed trays into deeper trays or larger post, or you can sow them directly where they are to grow. We plant all kinds of salad, spring onions, pak choi and radish in ours.
Bottom / large tub plants
Seedlings can be transplanted from your seed trays into the bottom level, or planted in place. For crops like spinach, you’ll get more from the season if you start your seeds in the top while plants in the bottom are still maturing … then when you harvest the plants in the bottom you have strong seedlings ready to transplant.
Single-cropping vegetables like Chard can be transplanted once at the beginning of the year, then left to their own devices for the rest of the season. Chard is a great one for cropping right to the end of the year, and even over winter if you live in a warmer location.
Tomatoes should be grown in the bottom level because they need a lot of height. You might even choose to remove the trays and tubs from one side of your greenhouse to give them more room.
Our favourites for growing in a Harvst mini-greenhouse
These crops are ideal:
Sow where they are to crop.
- Leafy greens like spinach and chard.
Either sow where they are to crop, or for more productivity and to get multiple crops from a season, start your second crop in trays while the main crop is still growing.
- Spring onions.
Sow where they are to crop.
Sow where they are to crop.
- Pak choi and oriental veg.
Either sow where they are to crop, or transplant from seed trays or cells.
Sow directly where they are to crop.
- Many flower varieties either start as annual, semi annual or perennial seeds in the Harvst greenhouse
Unsuitable for growing in a Harvst greenhouse
While you can start most plants off in a Harvst mini greenhouse, some will need to be moved outside to grow fully. The following are not suitable to grow to full size inside (mainly because there just isn’t enough space):
- Squash and pumpkin
- Sweet corn