April In The Greenhouse

The greenhouse soil has worked hard in the summer heat, and needs a bit of love before planting the next lot of crops out.

Create space

Lettuce seedlings planted beneath pruned tomatoes in the the greenhouse

As long as tomatoes, peppers, cucumbers and aubergines are still producing, leave them in for handy little harvests. Give them a big clean up though, to free up space at their base.

Remove as many ratty, older, yellow, pest-y or diseased foliage as you can and pluck any foliage that’s shading flowers and fruits who need the extra light and airflow on these shorter, cooler days.

  • If space is at a premium, you can cut tomatoes off at the base, leaving the nourishing roots behind in the soil, and hang the plants upside down in the greenhouse or on a porch where they’ll continue to ripen.
  • Another alternative is to use the unripe fruits in green tomato pickles, sauces et al. There will at some point, in my house, be fried green tomatoes for lunch – my fav.

Bring back the moisture!

If soils dry (and chances are that it is), you’ll need to rehydrate it to get the microbes back.

Soils that are really dry may take a few soaks to become properly moist. Water until puddles show, then rest it for a few hours or over night and repeat until your soil test shows you its perfectly moist.

If soils beyond dry – it will repel water and liquid will run right off the top. In this case crack the hydrophobic surface by making shallow drills along the bed. Water the drills a few times, resting between each, before watering the whole bed. As the water pathways re open and clay particles swell, the soil will start accepting water again.

Feed it up

Nothing beats a fresh layer of compost. Spread it on as thickly as possible – atleast 2cm in a greenhouse and ideally over the whole bed.

If you don’t have enough for the whole bed, no worries, here’s some ideas:

  • A dollop of compost for each new plant + crimson clover or any other nitrogen fixing greencrop + phacelia (greencrop) seed sprinkled on the un-composted bits between.
  • A dollop of compost for each seedling and trench foodscraps or better yet bokashi between plants.
  • Extend your homemade compost with any other decomposed organic matter you have to hand – well rotten manure, worm castings, the wormy soil beneath the firewood pile – mix it altogether and spread it on. I call this cheats compost and its served me very well over the years.

Boost the microbes

Saturate the prepared soil with something to stir the soil life into action. This little pre plant booster is so very good, especially if your soils dried out. Use whatever you have to hand.

I love a biological brew. But its not the only option:

  • worm juice
  • activated compost tea
  • liquid comfrey
  • organic blackstrap molasses + organic whole milk – both of which inspire a flush of biology. Dissolve 1T molasses in warm water and stir it into a 50/50 ish mix of water and organic, whole milk.

Plant + Sow

Bean seedlings in a plug tray ready to be transplanted

There’s heaps of cool things you can plant in the autumn greenhouse. It depends, of course, on what you want to eat + what the temperature is at yours.

  • Quick leafy’s like saladings, bok choy, gai lan or spinach will grow speedily in the warmth.
  • Dwarf beans are another excellent option at this time of year.
  • Beetroot
  • Spuds in buckets
  • Celery, because going under cover prevents rust.
  • Basil is a punt worth taking – if it suddenly gets too cold and comes to nothing, ah well!

If your chooks will be coming into the greenhouse in winter, group your new crops together by the door so you can get to them and at the same time screen them off from your chickens marauding feet.

Sow as many greencrops as you can fit in, beneath taller crops and finishing crops or in any remaining space. They’ll provide a nourishing feed for the soil and a most useful diversification from solanaceae (toms/ pepper/ aubergine) crops. Mustard, buckwheat, daikon and phacelia is my go to mixture. If your chooks will be coming into the greenhouse in winter, this will provide them plenty of organic matter to turn into the soil. Such easy, high value fertility!

If you are chicken-less and weed burden is high, simply grab your Niwashi shark and slash the weeds at the base and lay them back down as mulch.


  1. Carol Robson says

    Hi Kath
    I have a big pile of dead grass thanks to grass grub. I don’t want to throw it away. It would be okay as a mulch in my glasshouse or do you think it might still harbour more grubs that will eat my roots that I have growing in there now?

    Really love all the information you put on this site. Thank you!

    • Hey Carol, I highly doubt there’ll any grub in the dead grass – it lives and feeds on roots then transforms into a shiny brown beetle that nibbles plants – so you’ll be safe as to use it.

  2. Danielle Hart says

    Hey Kath,
    I’m interested to try the molasses and milk thing. Just wondering roughly how much of the 50/50 water/milk would you put with 1T molasses?

    • Ah fun! I go for 1 T blackstrap unsulphured molasses with a 50/50 raw milk water mixture in a watering can so thats about 9litres all up. This is super flexible – worth trying it and seeing how your plants like it.

  3. Lynda Rose Cartmell says

    Hi Kath,
    I have 3 free standing planter boxes in my Greenhouse which have been growing crops for 2 years now. I have used Daltons Garden Mix when I filled them. I feel it is time to maybe plant a Green crop and give the soil a rest. Is this the right time of the year and what Green Crop would you suggest?
    Many thanks for your time and hope you enjoy your “Coffee” .
    Kind regards,
    Lynda Cartmell

    • Hi Lynda
      Yes you can do a greencrop at anytime of year – right now is perfect for a rest for winter and as per the article above I’ve suggested a greencrop of phacelia mustard and buckwheat. You could also add lupin to that if you wanted. Cheers Kath

  4. Hi Kath, we have moved into a property that has a greenhouse, it was full of couch which we have sprayed (& its seems to have all died off) but the roots are so deep into the soil, what is the best way to get rid of these so we can start building up the soil and plant it out?

    • Hi Jan, thats a big answer, because its never as simple as “getting rid off”. Especially regards tricky couch.
      Unfortunately spraying has sent your soil health backwards, though it can be repaired easily. Spraying is of course a temporary measure – the couch will be back.
      For permanent change read this https://www.ediblebackyard.co.nz/smart-weeding-no-spraying-required/. The only way to move weeds on is to improve and build soil – the very best route longterm. If you get stuck, I’m available for 20 minute garden coach sessions.

  5. Mandy Richards says

    Hi Kath, I’m excited to build a greenhouse. Do you recommend polycarbonate or glass for optimal growing conditions?
    Also thanks for all your tips – your blog is so inspiring!!

    • Hey Mandy, great question, I keep hoping for time to write this up! There are pros and cons to both – so depends on your situation/ site….quality polycarb is probably my go to because its tougher against hail, soccer balls… life! and it diffuses light compared to glass, which depending on where you live is to your plants advantage – glass can be too much for plants, though easily mitigated by slinging shadecloth over overhead wires in peak summer. Glass is way easier to clean – which sounds boring but cleaning is an essential annual event. Polycarb (depending on the product) usually retains warmth better too. A good NZ greenhouse manufacturer ie not the general hardware store or trade me – will see you right. Useful when things need replacing down the track as well. If you really want to produce food, its worth spending a bit of money on something good/lasting/nice to work in if you can.