Yes, you can reuse soil aphid plants grew in without much worry. Aphids live on plant parts above ground rather than in the dirt below. The pests need fresh sap from living tissue to survive at all. Once you pull the plant out, any aphids left behind will die off fast.
I reuse aphid infested potting soil from my containers every year. Last season I had badly hit pepper plants in three large pots. I pulled the plants, added fresh compost, and planted new starts in the same mix. Those new plants grew fine with no aphid problems showing up from the old soil.
Aphids feed by piercing stems and leaves to drink the sap inside. They cannot survive in dirt without a host plant to feed on. This makes them different from soil dwelling pests that wait in the ground. Your reused soil poses no real risk of bringing back regular aphid species.
Root aphids are the one exception you should know about for recycling garden soil. These pests live underground and feed on plant roots instead of leaves. Check for woolly white clusters in the root zone before you reuse any soil. If you see them, treat or toss that batch of dirt instead.
I always pull out all plant debris before reusing my potting mix. Dead leaves and stems can harbor other problems like fungal spores or insect eggs. A clean start gives your new plants the best chance to thrive. Take a few minutes to pick out the old bits before replanting.
Mixing in fresh compost refreshes old soil and adds nutrients back in. I blend about one part new compost to four parts old mix. This ratio gives my plants a boost without changing the soil structure too much. The new plants grow strong right from the start with this blend.
Solarizing your soil kills any hidden pests or diseases if you want extra peace of mind. Put the mix in clear plastic bags and leave them in hot sun for four to six weeks. The heat builds up inside and cleans the soil of problems. This step takes time but works well for worried gardeners.
Container soil can be reused for three to four seasons with good care. Add fresh compost and check for pests each time you recycle it. Watch your new plants for any signs of trouble in the first few weeks. Most of the time your reused mix will work just as well as fresh bags from the store.
Read the full article: How to Control Aphids: Proven Methods Guide
